TWI825088B - Clamping apparatus and lithographic apparatus - Google Patents
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- G—PHYSICS
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- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70691—Handling of masks or workpieces
- G03F7/707—Chucks, e.g. chucking or un-chucking operations or structural details
- G03F7/70708—Chucks, e.g. chucking or un-chucking operations or structural details being electrostatic; Electrostatically deformable vacuum chucks
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/70858—Environment aspects, e.g. pressure of beam-path gas, temperature
- G03F7/70866—Environment aspects, e.g. pressure of beam-path gas, temperature of mask or workpiece
- G03F7/70875—Temperature, e.g. temperature control of masks or workpieces via control of stage temperature
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
- H01L21/6831—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using electrostatic chucks
- H01L21/6833—Details of electrostatic chucks
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Abstract
Description
本發明係關於一種包含靜電夾具之設備，及一種其操作方法。更特定言之但非獨占式地，該設備可包含微影工具、經組態以在微影圖案化期間夾持諸如圖案化器件之組件之靜電夾具。 The present invention relates to a device including an electrostatic clamp and a method of operating the same. More specifically, but not exclusively, the apparatus may include a lithography tool, an electrostatic clamp configured to hold components such as patterned devices during lithography patterning.
微影設備為經建構以將所要圖案施加至基板上之機器。微影設備可用於(例如)積體電路(IC)製造中。舉例而言，微影設備可將圖案化器件(例如光罩或倍縮光罩)處之圖案投影至提供於基板上之輻射敏感材料(抗蝕劑)層上。 Lithography equipment is a machine constructed to apply a desired pattern to a substrate. Lithography equipment may be used, for example, in integrated circuit (IC) manufacturing. For example, a lithography apparatus may project a pattern at a patterned device (eg, a reticle or reticle) onto a layer of radiation-sensitive material (resist) provided on a substrate.
為了將圖案投影於基板上，微影設備可使用電磁輻射。此輻射之波長判定可形成於基板上之特徵之最小大小。與使用例如具有193nm之波長之輻射的微影設備相比，使用具有在4nm至20nm之範圍內(例如6.7nm或13.5nm)之波長之極紫外線(EUV)輻射的微影設備可用以在基板上形成較小特徵。 To project patterns onto substrates, lithography equipment may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. In contrast to lithography equipment that uses radiation with a wavelength of, for example, 193 nm, lithography equipment that uses extreme ultraviolet (EUV) radiation with a wavelength in the range of 4 nm to 20 nm, such as 6.7 nm or 13.5 nm, can be used to print on the substrate. form smaller features.
微影設備通常可使用高電壓靜電夾具以便例如在圖案化操作期間夾持圖案化器件。靜電夾具及圖案化器件常常被維持處於低壓富氫環境中。此環境係非導電的。因此，應理解，電荷可積聚於介電表面或未接地表面上。舉例而言，在操作期間，電荷可藉由觸摸部分(例如光罩夾 持)或藉由在氣體流動期間之粒子碰撞而累積於介電表面或未接地表面上。 Lithography equipment may typically use high voltage electrostatic clamps to hold patterned devices, for example, during patterning operations. Electrostatic fixtures and patterned devices are often maintained in low-pressure, hydrogen-rich environments. This environment is non-conductive. Therefore, it should be understood that charge can accumulate on dielectric or ungrounded surfaces. For example, during operation, the charge can be transferred by touching parts such as the reticle holder persist) or accumulate on dielectric or ungrounded surfaces through particle collisions during gas flow.
亦應理解，歸因於產生EUV誘發之氫電漿，EUV輻射可致使富氫環境變得導電。在EUV誘發之氫電漿內產生之自由電荷可被吸引至由靜電夾具產生之電場(或由該等電場排斥)。另一方面，在不存在EUV誘發之電漿的情況下或在與任何EUV誘發之電漿相隔一定距離或經良好掩蔽免於任何EUV誘發之電漿影響的區中，電荷可累積於介電表面或未接地表面上，且可在任何電場已被移除之後繼續存在。 It should also be understood that EUV radiation can cause a hydrogen-rich environment to become electrically conductive due to the generation of EUV-induced hydrogen plasma. Free charges generated within the EUV-induced hydrogen plasma can be attracted to (or repelled by) the electric fields generated by the electrostatic clamps. On the other hand, charge can accumulate in the dielectric in the absence of EUV-induced plasma or in regions that are at a distance from or well-shielded from any EUV-induced plasma. on a surface or an ungrounded surface and may continue to exist after any electric field has been removed.
除了電荷累積以外，亦可在靜電夾具之部件與其他系統組件之間產生極強靜電場(例如大約~1kV/cm至100kV/cm)。詳言之，施加至靜電夾具之電極之高電壓導致附近導體(例如可存在於光罩之表面上之導電塗層)極化。因而，產生強靜電場，尤其是在尖銳特徵(例如導電光罩塗層之邊緣)處。施加至靜電夾具電極之電壓之極性可被頻繁切換，以避免在靜電夾具之絕緣內崩潰。在此類轉變期間，夾具周圍之區中之靜電場可快速改變。 In addition to charge accumulation, extremely strong electrostatic fields (e.g., approximately ~1kV/cm to 100kV/cm) can also be generated between components of the electrostatic fixture and other system components. In particular, high voltages applied to the electrodes of the electrostatic chuck cause nearby conductors, such as conductive coatings that may be present on the surface of the reticle, to polarize. As a result, strong electrostatic fields are generated, especially at sharp features such as the edges of conductive photomask coatings. The polarity of the voltage applied to the electrostatic clamp electrodes can be frequently switched to avoid breakdown within the insulation of the electrostatic clamp. During such transitions, the electrostatic field in the area surrounding the fixture can change rapidly.
本發明之一目標為預防或減輕與微影設備內之電荷累積及/或微影設備內之靜電場之產生及切換相關聯的一或多個問題。 It is an object of the present invention to prevent or mitigate one or more problems associated with charge accumulation within the lithography apparatus and/or the generation and switching of electrostatic fields within the lithography apparatus.
根據本發明之一第一態樣，提供一種設備，其包含用於夾持一組件之一靜電夾具，及用於與該靜電夾具相鄰地產生自由電荷之一機構。用於產生自由電荷之該機構經組態以在自該靜電夾具之一第一激勵狀態至該靜電夾具之一第二激勵狀態之一轉變期間與該靜電夾具相鄰地產生自由電荷。 According to a first aspect of the invention, there is provided an apparatus comprising an electrostatic clamp for clamping a component, and a mechanism for generating free charges adjacent to the electrostatic clamp. The mechanism for generating free charges is configured to generate free charges adjacent the electrostatic clamp during a transition from a first energized state of the electrostatic clamp to a second energized state of the electrostatic clamp.
藉由在再極化期間在靜電夾具周圍提供自由電荷(例如經由EUV誘發之H2電漿)，將在該夾具及任何經夾持圖案化器件附近提供相對導電介質。因而，隨著夾具再極化，大量自由電荷將有效地掩蔽由該夾具產生之任何外部場，且尤其是由延伸超出經夾持圖案化器件之夾具區(例如引線及接點)產生之任何外部場，藉此降低自夾具之此等區之表面釋放粒子之可能性。 By providing free charge around the electrostatic clamp during repolarization (eg via EUV-induced H2 plasma), a relatively conductive medium will be provided near the clamp and any clamped patterned devices. Thus, as the clamp repolarizes, the large amount of free charge will effectively mask any external fields generated by the clamp, and especially any generated by the clamp areas (such as leads and contacts) that extend beyond the clamped patterned device. The external field thereby reduces the possibility of particle release from the surface of these regions of the fixture.
應瞭解，在使用中，當組件由靜電夾具夾持時，該組件將遮擋靜電夾具之部件不受所產生之自由電荷影響。因此，雖然用於產生自由電荷之機構可經組態以與靜電夾具相鄰地產生自由電荷，但此類電荷在使用中通常將被防止到達夾具之由正被夾持組件直接遮擋之區。亦即，在使用中，所產生之自由電荷將提供至夾具之並未促成夾持力之區之掩蔽。實際上應理解，在夾持期間，經夾持組件將由夾具與組件之間所產生之場夾持，且存在於夾具及經夾持組件附近之自由電荷將不干涉此夾持效應。實情為，自由電荷通常將不延伸至夾具與經夾持組件之間的區中(其可例如在某些地點具有約10μm之最大分離度，且在其他地點直接接觸)。 It should be understood that in use, when a component is clamped by an electrostatic chuck, the component will shield the components of the electrostatic chuck from the free charge generated. Therefore, while a mechanism for generating free charges may be configured to generate free charges adjacent an electrostatic clamp, such charges in use will generally be prevented from reaching areas of the clamp that are directly obscured by the component being clamped. That is, in use, the free charge generated will provide masking of areas of the clamp that do not contribute to the clamping force. In practice, it should be understood that during clamping, the clamped component will be clamped by the field generated between the clamp and the component, and the free charges present in the vicinity of the clamp and clamped component will not interfere with this clamping effect. The reality is that the free charges will generally not extend into the area between the clamp and the clamped component (which may, for example, have a maximum separation of about 10 μm at some locations, and direct contact at other locations).
該靜電夾具可包含經組態以夾持該組件之一夾持區。當一組件被夾持時，可在該夾持區與該組件之間產生一夾持電場。 The electrostatic clamp may include a clamping region configured to clamp the component. When a component is clamped, a clamping electric field can be generated between the clamping area and the component.
該靜電夾具可進一步包含一非夾持區。當一組件由該夾持區夾持時，可在該非夾持區周圍產生一次級電場。 The electrostatic clamp may further include a non-clamping area. When a component is clamped by the clamping area, a secondary electric field can be generated around the non-clamping area.
舉例而言，在該非夾持區周圍不存在一接地導電介質的情況下，可在該非夾持區與該設備之一部分及/或該經夾持組件之一部分中之一或多者之間產生一次級電場。 For example, in the absence of a grounded conductive medium surrounding the non-clamped region, a voltage may be generated between the non-clamped region and one or more of a portion of the device and/or a portion of the clamped component. primary electric field.
該夾具可包含經組態以支撐圖案化器件之第一區及並未經 組態以支撐圖案化器件之第二區。該第一區可包含一或多個夾持電極。該第二區可包含一或多個次級電極。該等次級電極中之每一者可對應於該等夾持電極中之一各別夾持電極。該第二區可包含複數個非相連子區。舉例而言，該第二區可包含在該第一區之任一側上延伸之突起部。 The fixture may include a first region configured to support the patterned device and may not be A second region configured to support the patterned device. The first region may contain one or more clamping electrodes. The second region may include one or more secondary electrodes. Each of the secondary electrodes may correspond to a respective one of the clamping electrodes. The second region may include a plurality of non-contiguous sub-regions. For example, the second region may include protrusions extending on either side of the first region.
該等(夾持及次級)電極中之每一者可用介電材料塗佈。該介電材料可具有約100μm之厚度。 Each of the (clamp and secondary) electrodes may be coated with a dielectric material. The dielectric material may have a thickness of approximately 100 μm.
該第一區可包含夾持區。該第二區可包含非夾持區。當然應瞭解，在一些實施例中，一經夾持組件可具有大體上相似於該第一區之大小的大小。然而，在替代實施例中，一經夾持組件可具有小於該第一區之大小使得當被夾持時，該第一區之一些部分係由該經夾持組件覆蓋，而該第一區之其他部分未由該經夾持組件覆蓋。在此配置中，該第一區之未覆蓋部分可被認為包含非夾持區。 The first zone may include a clamping zone. The second area may include a non-clamping area. It will of course be appreciated that in some embodiments, a clamped component may have a size substantially similar to the size of the first region. However, in alternative embodiments, a clamped component may have a size smaller than the first region such that when clamped, some portion of the first region is covered by the clamped component, while the first region is Other parts are not covered by the clamped assembly. In this configuration, the uncovered portion of the first region can be considered to include the non-clamped region.
該設備可包含用於與該非夾持區相鄰地產生自由電荷之一機構。用於產生自由電荷之該機構可經組態以在自該靜電夾具之該第一激勵狀態至該靜電夾具之該第二激勵狀態之一轉變期間與該非夾持區相鄰地產生自由電荷。 The device may include a mechanism for generating free charges adjacent the non-clamped region. The mechanism for generating free charge may be configured to generate free charge adjacent the non-clamped region during a transition from the first energized state of the electrostatic clamp to the second energized state of the electrostatic clamp.
該靜電夾具包含至少一個電極，其中當一組件由該靜電夾具夾持時，一夾持電壓經施加至該至少一個電極使得在該夾持區與該組件之間產生該夾持電場。 The electrostatic clamp includes at least one electrode, wherein when a component is clamped by the electrostatic clamp, a clamping voltage is applied to the at least one electrode to generate the clamping electric field between the clamping area and the component.
該第一區可包含複數個夾持電極。在該靜電夾具之該第一激勵狀態中，可將一第一夾持電壓施加至該複數個電極中之一第一夾持電極，且可將一第二夾持電壓施加至該複數個夾持電極中之一第二夾持電極。該第一夾持電壓與該第二夾持電壓可具有相反的極性。 The first region may include a plurality of clamping electrodes. In the first energized state of the electrostatic clamp, a first clamping voltage can be applied to a first clamping electrode of the plurality of electrodes, and a second clamping voltage can be applied to the plurality of clamps. One of the holding electrodes is a second holding electrode. The first clamping voltage and the second clamping voltage may have opposite polarities.
該設備可進一步包含一電壓源。該電壓源可經組態以供應該夾持電壓。該夾持電壓可例如為約±1kV至10kV之電壓。該夾持電壓可例如為約±2kV之電壓。 The device may further include a voltage source. The voltage source can be configured to supply the clamping voltage. The clamping voltage may be, for example, a voltage of about ±1 kV to 10 kV. The clamping voltage may be, for example, a voltage of approximately ±2kV.
該靜電夾具可進一步包含經組態以提供至該至少一個電極之一電連接之至少一個接點。用於產生自由電荷之該機構可經組態以在自該靜電夾具之該第一激勵狀態至該靜電夾具之該第二激勵狀態之該轉變期間與該至少一個接點相鄰地產生自由電荷。 The electrostatic clamp may further include at least one contact configured to provide an electrical connection to the at least one electrode. The mechanism for generating free charge may be configured to generate free charge adjacent the at least one contact during the transition from the first energized state of the electrostatic clamp to the second energized state of the electrostatic clamp .
在該第一激勵狀態中，可將具有一第一極性之一電壓施加至該至少一個電極。在該第二激勵狀態中，可將具有與該第一極性相反之一第二極性之一電壓施加至該至少一個電極。 In the first excitation state, a voltage having a first polarity may be applied to the at least one electrode. In the second excitation state, a voltage having a second polarity opposite to the first polarity may be applied to the at least one electrode.
該電壓源可經組態以供應具有一第一極性之該電壓及/或具有該第二極性之該電壓。 The voltage source may be configured to supply the voltage with a first polarity and/or the voltage with the second polarity.
該靜電夾具可包含至少兩個電極。在該第一激勵狀態中，可將具有該第一極性之一電壓施加至該等電極中之一第一電極且可將具有該第二極性之電壓施加至該等電極中之一第二電極。在該第二激勵狀態中，可將具有該第二極性之一電壓施加至該等電極中之該第一電極且可將具有該第一極性之電壓施加至該等電極中之該第二電極。 The electrostatic clamp may include at least two electrodes. In the first excitation state, a voltage having the first polarity can be applied to a first electrode of the electrodes and a voltage having the second polarity can be applied to a second electrode of the electrodes. . In the second excitation state, a voltage having the second polarity can be applied to the first electrode of the electrodes and a voltage having the first polarity can be applied to the second electrode of the electrodes. .
該靜電夾具可進一步包含至少兩個次級電極。在該第一激勵狀態中，可將具有該第一極性之該電壓施加至該等次級電極中之一第一次級電極且可將具有該第二極性之該電壓施加至該等次級電極中之一第二次級電極。在該第二激勵狀態中，可將具有該第二極性之該電壓施加至該等次級電極中之該第一次級電極且可將具有該第一極性之該電壓施加至該等次級電極中之該第二次級電極。 The electrostatic clamp may further include at least two secondary electrodes. In the first excitation state, the voltage having the first polarity may be applied to one of the secondary electrodes and the voltage having the second polarity may be applied to the secondary electrodes. One of the electrodes is the second secondary electrode. In the second excitation state, the voltage having the second polarity can be applied to the first of the secondary electrodes and the voltage having the first polarity can be applied to the secondary electrodes. The second secondary electrode among the electrodes.
該等電極中之該第一電極可電連接至該等次級電極中之該第一次級電極。該等電極中之該第二電極可電連接至該等次級電極中之該第二次級電極。 The first electrode of the electrodes can be electrically connected to the first secondary electrode of the secondary electrodes. The second electrode of the electrodes can be electrically connected to the second secondary electrode of the secondary electrodes.
該夾具可經組態成使得在該第一及第二激勵狀態中之每一者中，一組件可由該靜電夾具夾持。 The clamp can be configured such that in each of the first and second energized states, a component can be clamped by the electrostatic clamp.
用於與該靜電夾具相鄰地產生自由電荷之該機構可包含一氣體源，及經組態以電離由該氣體源提供之氣體之一電離輻射源。 The mechanism for generating free charges adjacent the electrostatic clamp may include a gas source, and a source of ionizing radiation configured to ionize gas provided by the gas source.
該電離輻射源可包含選自由以下各者組成之群組之一源：一EUV源、一VUV源、一軟x射線源及一放射性源。 The ionizing radiation source may include a source selected from the group consisting of an EUV source, a VUV source, a soft x-ray source, and a radioactive source.
亦可提供一種經配置以將一圖案自一圖案化器件投影至一基板上之微影設備。該微影設備可包含根據本發明之該第一態樣之一設備。該圖案化器件可包含待夾持之該組件。 A lithography apparatus configured to project a pattern from a patterned device onto a substrate may also be provided. The lithography apparatus may comprise an apparatus according to the first aspect of the invention. The patterned device may include the component to be clamped.
該微影設備可進一步包含經組態以調節一輻射光束之一照明系統。該靜電夾具可經組態以夾持該圖案化器件。該圖案化器件可能夠在該輻射光束之橫截面中向該輻射光束賦予一圖案以形成一經圖案化輻射光束。該微影設備可進一步包含經建構以固持一基板之一基板台。該微影設備可進一步包含經組態以將該經圖案化輻射光束投影至該基板上之一投影系統。 The lithography apparatus may further include an illumination system configured to modulate a radiation beam. The electrostatic clamp can be configured to clamp the patterned device. The patterning device may be capable of imparting a pattern to the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam. The lithography apparatus may further include a substrate stage configured to hold a substrate. The lithography apparatus may further include a projection system configured to project the patterned radiation beam onto the substrate.
該微影設備可經組態以執行複數次成像曝光，在此期間該輻射光束入射於該圖案化器件上，且在此期間該經圖案化輻射光束投影至該基板上。該靜電夾具可經組態以在該等成像曝光期間夾持該圖案化器件。在該複數次成像曝光之連續成像曝光之間，該靜電夾具可經組態以自該第一激勵狀態轉變至該第二激勵狀態。 The lithography apparatus can be configured to perform a plurality of imaging exposures during which the radiation beam is incident on the patterned device and during which the patterned radiation beam is projected onto the substrate. The electrostatic clamp can be configured to clamp the patterned device during the imaging exposures. The electrostatic clamp may be configured to transition from the first energized state to the second energized state between successive imaging exposures of the plurality of imaging exposures.
每一成像曝光可包含一晶圓上之複數個晶粒之曝光。該夾具可在一第一晶圓與一第二晶圓之曝光之間的一時段期間再極化。 Each imaging exposure may include exposure of a plurality of dies on a wafer. The fixture can be repolarized during a period between exposure of a first wafer and a second wafer.
亦可提供一種包含該微影設備之微影系統。 A lithography system including the lithography equipment can also be provided.
該微影系統可進一步包含經組態以產生該輻射光束之一輻射源。用於產生自由電荷之該機構可包含選自由以下各者組成之群組之電離輻射之一次級源：一EUV源、一VUV源、一軟x射線源及一放射性源。 The lithography system may further include a radiation source configured to generate the radiation beam. The mechanism for generating free charges may include a secondary source of ionizing radiation selected from the group consisting of an EUV source, a VUV source, a soft x-ray source, and a radioactive source.
該微影系統可進一步包含經組態以產生該輻射光束之一輻射源，其中用於產生自由電荷之該機構包含該輻射源。該輻射源可為一EUV源。 The lithography system may further include a radiation source configured to generate the radiation beam, wherein the mechanism for generating free charges includes the radiation source. The radiation source may be an EUV source.
該微影系統可經進一步組態以執行至少一次非成像曝光，在此期間該輻射光束入射於該圖案化器件上，且在此期間無輻射投影至該基板上；該非成像曝光係在該複數次成像曝光之連續成像曝光之間予以執行。 The lithography system can be further configured to perform at least one non-imaging exposure during which the radiation beam is incident on the patterned device and during which no radiation is projected onto the substrate; the non-imaging exposure is performed on the plurality of Performed between consecutive imaging exposures.
在一系列成像曝光期間，該微影設備可經進一步組態以在每一連續成像曝光之間執行一非成像曝光。 During a series of imaging exposures, the lithography apparatus may be further configured to perform a non-imaging exposure between each successive imaging exposure.
可在該非成像曝光期間執行自該靜電夾具之該第一激勵狀態至該靜電夾具之該第二激勵狀態之該轉變。 The transition from the first energized state of the electrostatic clamp to the second energized state of the electrostatic clamp may be performed during the non-imaging exposure.
藉由在非成像曝光期間將輻射光束提供於圖案化器件處，有可能藉助於電漿提供自由電荷源，該電漿將藉由存在於圖案化器件周圍之氣體分子(例如氫)之電離而產生。將既在由輻射光束直接照明之區中又在相鄰區中(例如歸因於擴散，及次級電子)產生電漿。以此方式，單一輻射光束(例如EUV輻射光束)可既用於成像目的，又在靜電夾具之再極化期間提供自由電荷源。 By providing a radiation beam at the patterned device during non-imaging exposure, it is possible to provide a source of free charge by means of a plasma that will be generated by ionization of gas molecules (such as hydrogen) present around the patterned device. produce. Plasma will be generated both in the area directly illuminated by the radiation beam and in adjacent areas (eg due to diffusion, and secondary electrons). In this way, a single radiation beam, such as an EUV radiation beam, can be used both for imaging purposes and to provide a source of free charge during repolarization of the electrostatic clamp.
該微影系統可受控制使得入射於圖案化器件上之輻射之量在每一成像曝光期間比在該非成像曝光期間更大。 The lithography system can be controlled such that the amount of radiation incident on the patterned device is greater during each imaging exposure than during the non-imaging exposure.
應理解，可以多種方式控制入射於圖案化器件上之輻射之量。舉例而言，可藉由使由輻射源產生之輻射之強度變化來控制輻射之量。替代地或另外，可藉由使入射於圖案化器件上之輻射光束之空間範圍變化(例如藉由使用遮光片或遮蔽葉片)來控制輻射之量。替代地或另外，可藉由使由輻射源產生之輻射脈衝之數目或頻率變化來控制輻射之量。 It will be appreciated that the amount of radiation incident on the patterned device can be controlled in a variety of ways. For example, the amount of radiation can be controlled by varying the intensity of the radiation produced by the radiation source. Alternatively or additionally, the amount of radiation can be controlled by varying the spatial extent of the radiation beam incident on the patterned device (eg, by using a mask or masking blades). Alternatively or additionally, the amount of radiation may be controlled by varying the number or frequency of radiation pulses generated by the radiation source.
舉例而言，提供足夠自由電荷以提供有用的掩蔽所需之輻射劑量(在預定時間段期間)可能小於執行成像曝光所需之輻射劑量。 For example, the radiation dose required to provide sufficient free charge to provide useful masking (during a predetermined period of time) may be less than the radiation dose required to perform an imaging exposure.
入射於圖案化器件上之輻射之量可自非成像曝光至該複數次成像曝光中之一者逐漸增加。 The amount of radiation incident on the patterned device may gradually increase from a non-imaging exposure to one of the plurality of imaging exposures.
在上述實施例中，遮光片或遮蔽葉片或遮蔽葉片配置因此可用以例如藉由部分阻擋輻射光束來控制產生於靜電夾具周圍之自由電荷之量。 In the embodiments described above, the light shield or shielding blade or shielding blade arrangement can thus be used to control the amount of free charge generated around the electrostatic fixture, for example by partially blocking the radiation beam.
值得一提的是，照射於遮光片或遮蔽葉片配置上之輻射光束之部分亦可導致產生自由電荷。因而，用於與靜電夾具相鄰地產生自由電荷之替代方式為將輻射光束提供於不同於圖案化器件之表面處，例如遮光片或遮蔽葉片之表面。如上文所提及，遮光片或遮蔽葉片配置可用以阻擋輻射光束到達圖案化器件或用以控制入射於圖案化器件上之輻射光束之空間延伸。歸因於輻射光束與存在於或提供於遮光片或光罩葉片配置周圍、遮光片或光罩葉片配置處或附近的氣體分子(例如氫)之相互作用，輻射光束或其一部分之施加至該(該等)遮光片或光罩葉片上亦可導致產生自由電荷。將既在由輻射光束直接照明之區中又在相鄰區中(例如歸因於擴 散，及次級電子)產生自由電荷。由於遮光片或光罩葉片配置通常比較接近於圖案化器件且因此比較接近於靜電夾具，故藉由輻照遮光片或光罩葉片配置所產生之自由電荷亦可導致與靜電夾具相鄰之自由電荷。藉由輻照遮光片或光罩葉片配置而產生自由電荷因此亦可被認為係用於產生與靜電夾具相鄰之自由電荷之機構。 It is worth mentioning that the portion of the radiation beam that strikes the shading sheet or shading blade arrangement may also result in the generation of free charges. Thus, an alternative for generating free charges adjacent to the electrostatic clamp is to provide the radiation beam at a surface other than the patterned device, such as a surface of a mask or masking blade. As mentioned above, a shield or shield blade configuration may be used to block the radiation beam from reaching the patterned device or to control the spatial extension of the radiation beam incident on the patterned device. The application of the radiation beam, or a portion thereof, to the radiation beam, or a portion thereof, is due to the interaction of the radiation beam with gas molecules (e.g., hydrogen) present or provided around, at or near the mask or mask blade arrangement. Free charges may also be generated on (these) light shields or mask blades. will be present both in the area directly illuminated by the radiation beam and in adjacent areas (e.g. due to expanded Scattered, and secondary electrons) generate free charges. Since the mask or mask blade configuration is typically closer to the patterned device and therefore closer to the electrostatic fixture, the free charges generated by irradiating the mask or mask blade configuration can also result in free charge adjacent to the electrostatic fixture. charge. The generation of free charges by irradiating a mask or mask blade arrangement may therefore also be considered a mechanism for generating free charges adjacent to an electrostatic fixture.
關於此與靜電夾具相鄰地產生自由電荷之方式，可指出，在遮光片或光罩葉片配置在自由電荷之產生期間完全遮光的狀況下，可避免任何非想要的輻照到達基板之風險。 Regarding this way of generating free charges adjacent to the electrostatic fixture, it may be pointed out that in the case of a mask or mask blade arranged to completely block light during the generation of free charges, the risk of any unintended radiation reaching the substrate is avoided .
根據本發明之一第二態樣，提供一種操作一設備之方法，該設備包含一靜電夾具，及用於與該靜電夾具相鄰地產生自由電荷之一機構。該方法包含：控制該靜電夾具以具有一第一激勵狀態；控制該靜電夾具以具有一第二激勵狀態；及在自該第一激勵狀態至該第二激勵狀態之一轉變期間，控制用於產生自由電荷之該機構以與該靜電夾具相鄰地產生自由電荷。 According to a second aspect of the invention, there is provided a method of operating a device including an electrostatic clamp and a mechanism for generating free charges adjacent to the electrostatic clamp. The method includes: controlling the electrostatic clamp to have a first energized state; controlling the electrostatic clamp to have a second energized state; and during a transition from the first energized state to the second energized state, controlling for The mechanism for generating free charges generates free charges adjacent to the electrostatic clamp.
該方法可進一步包含與該靜電夾具相鄰地提供一組件。當該靜電夾具係該第一及/或第二激勵狀態中之一者或兩者時，該組件可由該靜電夾具夾持。 The method may further include providing a component adjacent the electrostatic clamp. The component may be clamped by the electrostatic clamp when the electrostatic clamp is in one or both of the first and/or second energized states.
控制用於產生自由電荷之該機構以與該靜電夾具及/或該組件相鄰地產生自由電荷可包含與該靜電夾具及/或該組件相鄰地提供一氣體，及控制一電離輻射源以與該靜電夾具及/或該組件相鄰地提供電離輻射使得該氣體電離。 Controlling the mechanism for generating free charges to generate free charges adjacent the electrostatic clamp and/or the component may include providing a gas adjacent the electrostatic clamp and/or the component, and controlling a source of ionizing radiation to Ionizing radiation is provided adjacent the electrostatic clamp and/or the component to ionize the gas.
當然應瞭解，以上結合本發明之該第一態樣之該設備所描述之特徵中的任一者可與本發明之該第二態樣之該方法之特徵組合。 It will of course be understood that any of the features described above in connection with the apparatus of the first aspect of the invention may be combined with features of the method of the second aspect of the invention.
根據本發明之一第三態樣，提供一種微影設備，該微影設備包含：一照明系統，其經組態以調節一輻射光束；一支撐結構，其經建構以支撐一圖案化器件，該圖案化器件能夠在該輻射光束之橫截面中向該輻射光束賦予一圖案以形成一經圖案化輻射光束，該支撐結構包含經組態以夾持該圖案化器件之一靜電夾具；一基板台，其經建構以固持一基板；及一投影系統，其經組態以將該經圖案化輻射光束投影至該基板上。該微影設備經組態以執行一成像前曝光，在此期間該輻射光束入射於該圖案化器件上且在此期間無輻射投影至該基板上。入射於該圖案化器件上之輻射之量在該成像前曝光期間逐漸增加。該微影設備經組態以執行一成像曝光，其中由該圖案化器件圖案化之該輻射光束投影至該基板上。 According to a third aspect of the present invention, a lithography apparatus is provided. The lithography apparatus includes: an illumination system configured to adjust a radiation beam; a support structure configured to support a patterned device, The patterned device is capable of imparting a pattern to the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam, the support structure includes an electrostatic clamp configured to hold the patterned device; a substrate table , which is constructed to hold a substrate; and a projection system configured to project the patterned radiation beam onto the substrate. The lithography apparatus is configured to perform a pre-imaging exposure during which the radiation beam is incident on the patterned device and during which no radiation is projected onto the substrate. The amount of radiation incident on the patterned device gradually increases during the pre-imaging exposure. The lithography apparatus is configured to perform an imaging exposure in which the radiation beam patterned by the patterning device is projected onto the substrate.
EUV功率之逐漸或軟性斜升導致圖案化器件及靜電夾具周圍之區之電導率的逐漸增加。介質電導率之此逐漸增加並不致使靜電場以突然方式崩潰，而是允許電荷根據預先存在之場線朝向各個表面洩漏。此製程允許中和已由於先前夾具極化狀態而變得帶電之任何表面。相似地，可因此中和夾具或圖案化器件之表面上之任何帶電粒子。EUV功率之此逐漸增加可顯著減少發生之靜電放電之改變，且因此可降低粒子(其常常由放電事件產生)之產生速率。 A gradual or soft ramp up of EUV power results in a gradual increase in the conductivity of the area surrounding the patterned device and electrostatic fixture. This gradual increase in the conductivity of the medium does not cause the electrostatic field to collapse in an abrupt manner, but rather allows charges to leak toward various surfaces according to pre-existing field lines. This process allows neutralization of any surface that has become charged due to the previous fixture polarization state. Similarly, any charged particles on the surface of the fixture or patterned device can thus be neutralized. This gradual increase in EUV power can significantly reduce changes in the electrostatic discharge that occurs, and therefore can reduce the rate of particle production (which is often produced by discharge events).
該成像曝光可包含包含一叢發，該叢發包含複數個輻射脈衝。該等脈衝中之每一者可包含一大體上恆定之輻射劑量。應理解，在一成像曝光期間，該輻射光束可為脈衝式的，使得瞬時輻射強度並非始終均一。然而，在該成像曝光期間，脈衝速率可足夠高使得入射於圖案化器件及經圖案化基板上之輻射在包括數十、數百或數千個脈衝之參考座標內大體上均一。此外，脈衝速率足夠高使得由EUV輻射產生之任何電漿將很可 能持續的時間長於相鄰脈衝之間的間隙，使得一旦建立，將藉由進行中的脈衝達到及維持平衡電漿密度。 The imaging exposure may include a burst including a plurality of radiation pulses. Each of the pulses may contain a substantially constant dose of radiation. It should be understood that during an imaging exposure, the radiation beam may be pulsed such that the instantaneous radiation intensity is not uniform throughout. However, during the imaging exposure, the pulse rate can be high enough such that the radiation incident on the patterned device and patterned substrate is substantially uniform within a reference coordinate that includes tens, hundreds, or thousands of pulses. Furthermore, the pulse rate is high enough that any plasma generated by EUV radiation will likely Can last longer than the gap between adjacent pulses, so that once established, equilibrium plasma density will be achieved and maintained by ongoing pulses.
該成像前曝光可緊接在該成像曝光之前。 The pre-imaging exposure may immediately precede the imaging exposure.
該成像前曝光可包含一叢發，該叢發包含複數個輻射脈衝。 The pre-imaging exposure may include a burst containing a plurality of radiation pulses.
該成像曝光及/或該成像前曝光之每一脈衝可例如具有約100ns之持續時間，及約20μs之脈衝節距(亦即約50kHz之脈衝頻率)。 Each pulse of the imaging exposure and/or the pre-imaging exposure may, for example, have a duration of about 100 ns, and a pulse pitch of about 20 μs (ie, a pulse frequency of about 50 kHz).
在成像前曝光期間之脈衝速率可足夠高，使得在成像前曝光之每一脈衝中由入射EUV光子(直接地或間接地)產生之氫電漿持續的時間長於該等脈衝之相鄰脈衝之間的間隙。該叢發可包含複數個小型叢發，每一小型叢發包含複數個(例如高達10個)輻射脈衝。 The pulse rate during the pre-imaging exposure can be high enough such that the hydrogen plasma generated by incident EUV photons (directly or indirectly) in each pulse of the pre-imaging exposure lasts longer than adjacent pulses of those pulses. the gap between. The burst may contain a plurality of small bursts, each small burst containing a plurality (eg, up to 10) of radiation pulses.
在該成像前曝光期間之輻射之量的逐漸增加可經組態為遍及複數個該等輻射脈衝提供。 Gradual increases in the amount of radiation during the pre-imaging exposure can be configured to be provided over a plurality of such radiation pulses.
以此方式，隨著入射於圖案化器件上之輻射之量在成像前曝光期間逐漸增加，電漿密度可得以逐漸增加，從而引起圖案化器件周圍之區之電導率的所要逐漸增加。該逐漸增加可經組態為遍及複數個該等小型叢發提供。 In this manner, as the amount of radiation incident on the patterned device gradually increases during pre-imaging exposure, the plasma density can be gradually increased, thereby causing a desired gradual increase in the conductivity of the region surrounding the patterned device. This gradual increase can be configured to be provided across a plurality of these small bursts.
在該成像前曝光期間之輻射之該逐漸增加可經組態為遍及至少1000個輻射脈衝提供。 The gradual increase in radiation during the pre-imaging exposure may be configured to be provided over at least 1000 radiation pulses.
在具有約50kHz之脈衝頻率之系統中，將在約20ms內遞送1000個輻射脈衝。在該成像前曝光期間之輻射之該逐漸增加可經組態為遍及高達約50,000個輻射脈衝(亦即高達約1秒)提供。較佳地，在該成像前曝光期間之輻射之該逐漸增加可經組態為遍及高達約10,000個輻射脈 衝(亦即高達約0.2秒)提供。 In a system with a pulse frequency of about 50 kHz, 1000 radiation pulses will be delivered in about 20 ms. The gradual increase in radiation during the pre-imaging exposure can be configured to be provided over up to about 50,000 pulses of radiation (ie, up to about 1 second). Preferably, the gradual increase in radiation during the pre-imaging exposure may be configured over up to about 10,000 pulses of radiation. rush (i.e. up to approximately 0.2 seconds) is provided.
應理解，在增加輻射強度至成像所需之全強度所花費的時間(其若過長，則可降低晶圓產出率)與達成降低放電及/或粒子產生或釋放之可能性之益處之間存在折衷。 It should be understood that the time it takes to increase the radiation intensity to the full intensity required for imaging (which, if too long, can reduce wafer yield) is balanced by the benefit of achieving a reduced likelihood of discharge and/or particle generation or release. There are trade-offs.
在該成像前曝光期間之輻射之該逐漸增加可經組態為遍及複數個該等輻射脈衝大體上線性地提供。 The gradual increase in radiation during the pre-imaging exposure can be configured to be provided substantially linearly over a plurality of the radiation pulses.
輻射強度可針對複數個連續輻射脈衝中之每一者增加一預定量，使得入射於圖案化器件上之輻射強度以一基本線性方式逐漸增加。 The radiation intensity may be increased by a predetermined amount for each of a plurality of successive radiation pulses such that the intensity of radiation incident on the patterned device gradually increases in a substantially linear manner.
在具有一預定持續時間之該成像前曝光之一第一部分期間，該輻射光束可受控制以將輻射之一第一劑量遞送至該圖案化器件，該第一劑量包含在該成像曝光之一第一部分期間遞送至該圖案化器件之輻射之一成像劑量的不到約10%，該成像前曝光之該第一部分具有該預定持續時間。 During a first portion of the pre-imaging exposure having a predetermined duration, the radiation beam may be controlled to deliver a first dose of radiation to the patterned device, the first dose being included in a first portion of the imaging exposure. The first portion of the pre-imaging exposure has the predetermined duration during a portion of less than about 10% of an imaging dose of radiation delivered to the patterned device.
應理解，該成像前曝光之該第一部分及該成像曝光之該第一部分的實際持續時間並不重要。實情為，該設備受控制使得在該成像前曝光之該第一部分期間在一預定時間段(例如200μs)期間遞送的輻射之劑量小於在一對應預定時間段(例如200μs)期間遞送之輻射之劑量。 It should be understood that the actual duration of the first portion of the pre-imaging exposure and the first portion of the imaging exposure is immaterial. What is achieved is that the apparatus is controlled such that the dose of radiation delivered during a predetermined time period (e.g. 200 μs) during the first part of the pre-imaging exposure is less than the dose of radiation delivered during a corresponding predetermined time period (e.g. 200 μs) .
該第一劑量可包含一非零劑量。該第一劑量可包含在該成像曝光之該第一部分期間遞送至該圖案化器件之輻射之成像劑量的約5%。 The first dose may include a non-zero dose. The first dose may comprise about 5% of the imaging dose of radiation delivered to the patterned device during the first portion of the imaging exposure.
該成像前曝光之該第一部分可包含複數個脈衝。因而，該第一劑量可包含由該成像前曝光之該第一部分內之該複數個脈衝遞送的一總劑量。該成像曝光之該第一部分亦可包含複數個脈衝。因而，在該成像 曝光之該第一部分期間遞送至該圖案化器件之輻射的該成像劑量可包含由該成像曝光之該第一部分內之該複數個脈衝遞送的一總劑量。 The first portion of the pre-imaging exposure may include a plurality of pulses. Thus, the first dose may comprise a total dose delivered by the plurality of pulses within the first portion of the pre-imaging exposure. The first portion of the imaging exposure may also include a plurality of pulses. Therefore, in this imaging The imaging dose of radiation delivered to the patterned device during the first portion of the exposure may comprise a total dose delivered by the plurality of pulses within the first portion of the imaging exposure.
在該成像前曝光之該第一部分之前，由該輻射光束遞送至該圖案化器件之該輻射強度輻射可大體上為零。因此，該成像前曝光之該第一部分可構成自該成像劑量之約0%至該成像劑量之約5%的跳躍。 Prior to the first portion of the pre-imaging exposure, the radiation intensity radiation delivered by the radiation beam to the patterned device may be substantially zero. Accordingly, the first portion of the pre-imaging exposure may constitute a jump from about 0% of the imaging dose to about 5% of the imaging dose.
入射於該圖案化器件上之輻射之該量可自該成像前曝光之該第一部分至該成像曝光逐漸增加。 The amount of radiation incident on the patterned device may gradually increase from the first portion of the pre-imaging exposure to the imaging exposure.
在具有該預定持續時間之該成像前曝光之一第二部分(該第二部分在該第一部分之後)期間，該輻射光束可受控制以將輻射之一第二劑量遞送至該圖案化器件，該第二劑量大於該第一劑量且小於在該成像曝光之該第一部分期間遞送至該圖案化器件的輻射之該成像劑量。 The radiation beam may be controlled to deliver a second dose of radiation to the patterned device during a second portion of the pre-imaging exposure having the predetermined duration, the second portion following the first portion, The second dose is greater than the first dose and less than the imaging dose of radiation delivered to the patterned device during the first portion of the imaging exposure.
可在該成像前曝光之該第一部分之一開始與該成像曝光之一開始之間遞送至少1000個輻射脈衝。 At least 1000 radiation pulses may be delivered between the beginning of the first portion of the pre-imaging exposure and the beginning of the imaging exposure.
以此方式，該輻射劑量可自該成像前曝光之該第一部分至該成像曝光遍及跨越至少1000個輻射脈衝之一時段逐漸增加。 In this manner, the radiation dose may be gradually increased from the first portion of the pre-imaging exposure to the imaging exposure throughout a period spanning at least 1000 radiation pulses.
該微影設備可經進一步組態以執行一成像後曝光，在此期間該輻射光束入射於該圖案化器件上；且在此期間無輻射投影至該基板上，其中入射於該圖案化器件上之輻射之量在該成像後曝光期間逐漸減小且其中該成像後曝光在一成像曝光之後。 The lithography apparatus may be further configured to perform an imaging post-exposure during which the radiation beam is incident on the patterned device; and during which no radiation is projected onto the substrate during which it is incident on the patterned device The amount of radiation is gradually reduced during the imaging post-exposure and wherein the imaging post-exposure follows an imaging exposure.
該微影設備可經進一步組態以執行一第一成像曝光及一第二成像曝光。該成像前曝光可緊接在該第二成像曝光之前。在該第一成像曝光與該成像前曝光之間，該微影設備可經進一步組態以執行一非成像曝光，在此期間該輻射光束入射於該圖案化器件上且在此期間無輻射投影至 該基板上。 The lithography apparatus may be further configured to perform a first imaging exposure and a second imaging exposure. The pre-imaging exposure may immediately precede the second imaging exposure. Between the first imaging exposure and the imaging pre-exposure, the lithography apparatus may be further configured to perform a non-imaging exposure during which the radiation beam is incident on the patterned device and during which no radiation is projected to on this substrate.
在具有該預定持續時間之該非成像曝光之一第一部分期間，該輻射光束可受控制以將輻射之一第三劑量遞送至該圖案化器件，該第三劑量包含輻射之該成像劑量的不到約10%。該設備可經組態以致使該靜電夾具在該非成像曝光期間自一第一激勵狀態轉變至一第二激勵狀態。 During a first portion of the non-imaging exposure having the predetermined duration, the radiation beam may be controlled to deliver a third dose of radiation to the patterned device, the third dose comprising less than the imaging dose of radiation. About 10%. The apparatus can be configured to cause the electrostatic clamp to transition from a first energized state to a second energized state during the non-imaging exposure.
亦即，該夾具可在多個成像曝光之間的該非成像曝光期間再極化。 That is, the clamp can be repolarized during the non-imaging exposures between imaging exposures.
該微影設備可經進一步組態以致使該靜電夾具在該成像前曝光期間自一第一激勵狀態轉變至一第二激勵狀態。 The lithography apparatus may be further configured to cause the electrostatic clamp to transition from a first energized state to a second energized state during the pre-imaging exposure.
亦即，該夾具可在一成像曝光之前在EUV功率之斜升期間再極化。此允許在夾具再極化期間提供低位準之輻射(且因此提供相對較低電漿密度)，其中僅在成像曝光期間提供全輻射強度。該低位準之輻射可足以減輕與夾具再極化相關聯的負面結果中之一些(例如粒子釋放)，且可減小輻射源上之負荷。更一般而言，在施加至夾具之任何電壓改變期間，亦可有利地應用低位準輻射之施加。作為一實例，當將物件裝載至夾具上或自夾具卸載物件時，可有利地應用低位準輻射之施加。 That is, the fixture can be repolarized during a ramp-up of EUV power prior to an imaging exposure. This allows low levels of radiation (and therefore relatively low plasma density) to be provided during clamp repolarization, with full radiation intensity being provided only during imaging exposure. This low level of radiation may be sufficient to mitigate some of the negative consequences associated with fixture repolarization (such as particle release) and may reduce the load on the radiation source. More generally, the application of low level radiation may also be advantageously applied during any change in voltage applied to the fixture. As an example, the application of low level radiation may be advantageously used when loading or unloading items from a fixture.
在一系列成像曝光期間，該微影設備可經進一步組態以在每一連續成像曝光之間執行一非成像曝光。 During a series of imaging exposures, the lithography apparatus may be further configured to perform a non-imaging exposure between each successive imaging exposure.
應理解，可以多種方式控制入射於圖案化器件上之輻射之量。舉例而言，可藉由使由輻射源產生之輻射之強度變化來控制輻射之量。替代地或另外，可藉由使入射於圖案化器件上之輻射光束之空間範圍變化(例如藉由使用遮光片或遮蔽葉片)來控制輻射之量。替代地或另外，可藉由使由輻射源產生之輻射脈衝之數目或頻率變化來控制輻射之量。 It will be appreciated that the amount of radiation incident on the patterned device can be controlled in a variety of ways. For example, the amount of radiation can be controlled by varying the intensity of the radiation produced by the radiation source. Alternatively or additionally, the amount of radiation can be controlled by varying the spatial extent of the radiation beam incident on the patterned device (eg, by using a mask or masking blades). Alternatively or additionally, the amount of radiation may be controlled by varying the number or frequency of radiation pulses generated by the radiation source.
舉例而言，提供足夠自由電荷以提供有用的掩蔽所需之輻射劑量可能小於執行成像曝光所需之輻射劑量。 For example, the radiation dose required to provide sufficient free charge to provide useful masking may be less than the radiation dose required to perform an imaging exposure.
亦可提供一種包含本發明之該第三態樣之該微影設備的微影系統。該微影系統可進一步包含經組態以產生該輻射光束之一輻射源。該輻射源可為一EUV源。 A lithography system including the lithography apparatus according to the third aspect of the present invention can also be provided. The lithography system may further include a radiation source configured to generate the radiation beam. The radiation source may be an EUV source.
根據本發明之一第四態樣，提供一種操作一微影設備之方法。該微影設備包含：一照明系統，其經組態以調節一輻射光束；一支撐結構，其經建構以支撐一圖案化器件，該圖案化器件能夠在該輻射光束之橫截面中向該輻射光束賦予一圖案以形成一經圖案化輻射光束，該支撐結構包含經組態以夾持該圖案化器件之一靜電夾具；一基板台，其經建構以固持一基板；及一投影系統，其經組態以將該經圖案化輻射光束投影至該基板上。該方法包含致使該微影設備執行一成像前曝光，在此期間該輻射光束入射於該圖案化器件上，且在此期間無輻射投影至該基板上，其中入射於該圖案化器件上之輻射之量在該成像前曝光期間逐漸增加。該方法進一步包含致使該微影設備執行一成像曝光，其中由該圖案化器件圖案化之該輻射光束投影至該基板上。 According to a fourth aspect of the present invention, a method of operating a lithography apparatus is provided. The lithography apparatus includes: an illumination system configured to modulate a radiation beam; a support structure configured to support a patterned device capable of radiating radiation in a cross-section of the radiation beam The beam imparts a pattern to form a patterned radiation beam, the support structure includes an electrostatic clamp configured to hold the patterned device; a substrate stage configured to hold a substrate; and a projection system Configured to project the patterned radiation beam onto the substrate. The method includes causing the lithography apparatus to perform a pre-imaging exposure during which the radiation beam is incident on the patterned device and during which no radiation is projected onto the substrate, wherein the radiation incident on the patterned device The amount gradually increases during the exposure before imaging. The method further includes causing the lithography apparatus to perform an imaging exposure in which the radiation beam patterned by the patterning device is projected onto the substrate.
當然應瞭解，以上結合本發明之該第三態樣之該設備所描述之特徵中的任一者可與本發明之該第四態樣之該方法之特徵組合。 It will of course be understood that any of the features described above in connection with the apparatus of the third aspect of the invention may be combined with features of the method of the fourth aspect of the invention.
根據本發明之一第五態樣，提供一種設備，其包含：用於夾持一組件之一靜電夾具，及用於與該靜電夾具相鄰地產生自由電荷之一機構，該設備具有：一第一組態，其中一組件由該靜電夾具夾持；及一第二組態，其中該組件與該靜電夾具間隔開。該設備經組態為在一第一時間點處於該第一組態中且在該第一時間點之後的一第二時間點處於該第二組 態中。用於產生自由電荷之該機構經組態以在介於該第一時間點與該第二時間點之間的一第三時間點與該靜電夾具及/或該組件相鄰地產生自由電荷。 According to a fifth aspect of the present invention, a device is provided, which includes: an electrostatic clamp for clamping a component, and a mechanism for generating free charges adjacent to the electrostatic clamp, the device having: an A first configuration in which a component is clamped by the electrostatic clamp; and a second configuration in which the component is spaced apart from the electrostatic clamp. The device is configured to be in the first configuration at a first point in time and in the second group at a second point in time subsequent to the first point in time. in state. The mechanism for generating free charge is configured to generate free charge adjacent the electrostatic clamp and/or the component at a third time point between the first time point and the second time point.
在處置操作期間，例如在微影設備中之圖案化器件之移除期間，可在該設備中使用自由電荷，以防止與歸因於電容之改變之電壓放大相關聯的負面影響，該電容改變係與各種電隔離系統組件之間的增加之分離度相關聯。詳言之，隨著自夾具移除經夾持組件，其之間的電容將減小(與分離度成反比)。所產生之自由電荷可用以轉移電荷以減小電壓放大之效應，藉此減小放電之可能性(例如在超過帕申(Paschen)限制的情況下經由氫崩潰)。 During processing operations, such as during removal of patterned devices in a lithography equipment, free charges may be used in the equipment to prevent negative effects associated with voltage amplification due to changes in capacitance that change This is associated with increased separation between the various electrically isolated system components. In detail, as a clamped component is removed from the clamp, the capacitance between them will decrease (inversely proportional to the degree of separation). The free charges generated can be used to transfer charges to reduce the effects of voltage amplification, thereby reducing the likelihood of discharge (eg via hydrogen collapse if the Paschen limit is exceeded).
用於產生自由電荷之該機構可經組態以與該靜電夾具及/或該組件相鄰地產生自由電荷，以便防止該靜電夾具與該組件之間的一電位差超過一預定臨限值。 The mechanism for generating free charges may be configured to generate free charges adjacent the electrostatic clamp and/or the component to prevent a potential difference between the electrostatic clamp and the component from exceeding a predetermined threshold.
應理解，該自由電荷產生之時序及範圍兩者稍微具有靈活性。詳言之，若與靜電夾具與組件之間的增加之分離度相關聯的電容改變導致靜電夾具與組件之間的電位差超過臨限值(例如根據帕申定律之氫之崩潰電壓)，則放電可能發生。然而，亦應理解，最小放電電壓將取決於距離及氣壓兩者。因而，電壓臨限值將在一組態與另一組態之間變化。 It should be understood that there is some flexibility in both the timing and extent of free charge generation. In particular, a discharge occurs if the change in capacitance associated with the increased separation between the electrostatic clamp and the component causes the potential difference between the electrostatic clamp and the component to exceed a threshold value (e.g., the collapse voltage of hydrogen according to Paschen's law) may happen. However, it should also be understood that the minimum discharge voltage will depend on both distance and air pressure. Thus, the voltage threshold will vary from one configuration to another.
該預定臨限值係基於該設備中之一壓力予以判定。該壓力可為氫之壓力。 The predetermined threshold is determined based on a pressure in the device. The pressure may be that of hydrogen.
可選擇該第三時間點以便防止該靜電夾具與該組件之間的一電位差超過該預定臨限值。 The third time point may be selected to prevent a potential difference between the electrostatic clamp and the component from exceeding the predetermined threshold.
可在選定之時間(亦即第三時間點)產生該等自由電荷，以 便在該靜電夾具與該組件之間的該電位差超過該臨限值之前提供電荷以減小(或限制)該電位差。 These free charges can be generated at a selected time (ie, the third time point) to A charge is provided to reduce (or limit) the potential difference between the electrostatic clamp and the component before the potential difference exceeds the threshold value.
該預定臨限值可約為250V或更低，例如約130V。 The predetermined threshold may be about 250V or less, such as about 130V.
該設備可經組態為在該第三時間點處於該第二組態中。 The device may be configured to be in the second configuration at the third point in time.
詳言之，可在移除夾持電壓之後不久產生自由電荷，且組件開始與夾具分離。以此方式，所產生之自由電荷將容易能夠到達夾具及經夾持組件之表面。 In detail, free charge can be generated shortly after the clamping voltage is removed and the component begins to separate from the clamp. In this way, the free charge generated will be easily able to reach the surface of the clamp and the clamped component.
在該第三時間點，夾具之表面與組件之表面之間的最小分離度可大於約10微米。 At this third point in time, the minimum separation between the surface of the clamp and the surface of the component may be greater than about 10 microns.
夾具之表面可為當組件被夾持時與該組件接觸的夾具之表面。應瞭解，夾具可包含具備突起部(其可被稱作瘤節)之大體上平面表面。該等突起部可確保即使在夾持期間，夾具之大體上平面表面與組件之夾持表面之間的分離度亦超過最小值(例如10微米)。然而，在夾持期間，應理解，該等突起部之表面將與經夾持組件接觸，且因此，在夾持期間，夾具之表面與組件之表面之間的最小分離度為零。 The surface of the clamp may be a surface of the clamp that contacts the component when the component is clamped. It will be appreciated that the clamp may include a generally planar surface provided with protrusions, which may be referred to as knobs. The protrusions ensure that the separation between the generally planar surface of the clamp and the clamping surface of the component exceeds a minimum value (eg 10 microns) even during clamping. During clamping, however, it is understood that the surfaces of the protrusions will be in contact with the clamped component, and therefore, the minimum separation between the surface of the clamp and the surface of the component during clamping is zero.
在該第三時間點，夾具之表面與組件之表面之間的最小分離度可大於或等於約100微米。 At this third point in time, the minimum separation between the surface of the clamp and the surface of the component may be greater than or equal to about 100 microns.
在該第三時間點，夾具之表面與組件之表面之間的最小分離度可小於預定分離度。該預定分離度可約為200微米。 At the third point in time, the minimum separation between the surface of the clamp and the surface of the component may be less than the predetermined separation. The predetermined separation may be approximately 200 microns.
用於產生自由電荷之該機構可經組態以在該設備經組態為處於該第一組態中時與該靜電夾具及/或該組件相鄰地產生自由電荷。 The mechanism for generating free charges may be configured to generate free charges adjacent the electrostatic clamp and/or the component when the device is configured in the first configuration.
該設備可經組態為在該第三時間點處於該第一組態中。 The device may be configured to be in the first configuration at the third point in time.
應瞭解，在使用中，當組件由靜電夾具夾持時，該組件將 遮擋靜電夾具之部件不受所產生之自由電荷影響。因此，雖然用於產生自由電荷之機構可經組態以與靜電夾具相鄰地產生自由電荷，但此類電荷在使用中通常將被防止到達夾具之由正被夾持組件直接遮擋之區。然而，隨著組件與夾具分離(亦即在移除夾持電壓之後)，應理解，自由電荷可擴散至夾具及經夾持組件之表面，從而提供對電壓放大效應之補償。因此，當組件被夾持時與夾持器件及/或組件相鄰地產生之自由電荷可提供電壓放大之有效減小。 It should be understood that in use, when a component is held by an electrostatic clamp, the component will Shield the components of the electrostatic clamp from the free charge generated. Therefore, while a mechanism for generating free charges may be configured to generate free charges adjacent an electrostatic clamp, such charges in use will generally be prevented from reaching areas of the clamp that are directly obscured by the component being clamped. However, as the component is separated from the clamp (ie, after the clamping voltage is removed), it is understood that the free charge can diffuse to the surface of the clamp and clamped component, thereby providing compensation for the voltage amplification effect. Thus, free charge generated adjacent the clamping device and/or component when the component is clamped can provide an effective reduction in voltage amplification.
該靜電夾具可包含經組態以夾持該組件之一夾持區。當一組件被夾持時，可在該夾持區與該組件之間產生一夾持電場。 The electrostatic clamp may include a clamping region configured to clamp the component. When a component is clamped, a clamping electric field can be generated between the clamping area and the component.
該靜電夾具可包含至少一個電極。當一組件由該靜電夾具夾持時，可將一夾持電壓施加至該至少一個電極使得在該夾持區與該組件之間產生該夾持電場。 The electrostatic clamp may include at least one electrode. When a component is clamped by the electrostatic clamp, a clamping voltage can be applied to the at least one electrode to generate the clamping electric field between the clamping area and the component.
該設備可進一步包含一電壓源。 The device may further include a voltage source.
用於與該靜電夾具相鄰地產生自由電荷之該機構可包含一氣體源，及經組態以電離由該氣體源提供之氣體之一電離輻射源。 The mechanism for generating free charges adjacent the electrostatic clamp may include a gas source, and a source of ionizing radiation configured to ionize gas provided by the gas source.
該電離輻射源可包含選自由以下各者組成之群組之一源：一EUV源、一VUV源、一軟x射線源及一放射性源。 The ionizing radiation source may include a source selected from the group consisting of an EUV source, a VUV source, a soft x-ray source, and a radioactive source.
該設備可進一步包含經組態以自該靜電夾具移除該組件之一組件交換總成。 The apparatus may further include a component exchange assembly configured to remove the component from the electrostatic clamp.
該組件交換總成可經組態以控制該組件與該靜電夾具之間的分離度。 The component exchange assembly can be configured to control the degree of separation between the component and the electrostatic clamp.
亦可提供一種經配置以將一圖案自一圖案化器件投影至一基板上之微影設備。該微影設備可包含根據本發明之該第五態樣之一設 備。該圖案化器件可包含待夾持之該組件。 A lithography apparatus configured to project a pattern from a patterned device onto a substrate may also be provided. The lithography apparatus may include a device according to the fifth aspect of the present invention. Prepare. The patterned device may include the component to be clamped.
該微影設備可進一步包含：一照明系統，其經組態以調節一輻射光束。該靜電夾具可經組態以夾持該圖案化器件。該圖案化器件可能夠在該輻射光束之橫截面中向該輻射光束賦予一圖案以形成一經圖案化輻射光束。該微影設備可進一步包含：一基板台，其經建構以固持一基板；及一投影系統，其經組態以將該經圖案化輻射光束投影至該基板上。 The lithography apparatus may further include an illumination system configured to modulate a radiation beam. The electrostatic clamp can be configured to clamp the patterned device. The patterning device may be capable of imparting a pattern to the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam. The lithography apparatus may further include: a substrate stage configured to hold a substrate; and a projection system configured to project the patterned radiation beam onto the substrate.
亦可提供一種包含該微影設備之微影系統。該微影系統可進一步包含經組態以產生該輻射光束之一輻射源。 A lithography system including the lithography equipment can also be provided. The lithography system may further include a radiation source configured to generate the radiation beam.
用於產生自由電荷之該機構可包含選自由以下各者組成之群組之電離輻射之一次級源：一EUV源、一VUV源、一軟x射線源及一放射性源。 The mechanism for generating free charges may include a secondary source of ionizing radiation selected from the group consisting of an EUV source, a VUV source, a soft x-ray source, and a radioactive source.
用於產生自由電荷之該機構可包含該輻射源。該輻射源可為一EUV源。 The mechanism for generating free charges may include the radiation source. The radiation source may be an EUV source.
根據本發明之一第六態樣，提供一種操作一設備之方法。該設備包含一靜電夾具，及用於與該靜電夾具相鄰地產生自由電荷之一機構。該方法包含：與該靜電夾具相鄰地提供一組件；控制該靜電夾具以具有一第一組態，其中在一第一時間點該組件由該靜電夾具夾持；控制該靜電夾具以具有一第二組態，其中在該第一時間點之後的一第二時間點，該組件與該靜電夾具間隔開；及控制用於產生自由電荷之該機構以在介於該第一時間點與該第二時間點之間的一第三時間點與該靜電夾具及/或該組件相鄰地產生自由電荷。 According to a sixth aspect of the present invention, a method of operating a device is provided. The apparatus includes an electrostatic clamp and a mechanism for generating free charges adjacent the electrostatic clamp. The method includes: providing a component adjacent to the electrostatic clamp; controlling the electrostatic clamp to have a first configuration in which the component is clamped by the electrostatic clamp at a first time point; controlling the electrostatic clamp to have a A second configuration, wherein the component is spaced apart from the electrostatic clamp at a second time point after the first time point; and the mechanism for generating free charge is controlled to be between the first time point and the first time point. A third time point between the second time points generates free charge adjacent the electrostatic clamp and/or the component.
當然應瞭解，以上結合本發明之該第五態樣之該設備所描述之特徵中的任一者可與本發明之該第六態樣之該方法之特徵組合。 It will of course be understood that any of the features described above in connection with the apparatus of the fifth aspect of the invention may be combined with features of the method of the sixth aspect of the invention.
根據本發明之一第七態樣，提供一種設備，其包含用於夾持一組件之一靜電夾具，及用於鄰近於該靜電夾具產生自由電荷之一機構。該設備具有：一第一組態，其中具有一第一極性之一電壓經施加至至少一個夾具電極且無組件由該靜電夾具夾持；及一第二組態，其中具有與該第一極性相反的一第二極性之一電壓經施加至該至少一個夾具電極。該設備經組態為在一第一時間點處於該第一組態中且在該第一時間點之後的一第二時間點處於該第二組態中。用於產生自由電荷之該機構經組態以在該靜電夾具處於該第一組態中時與該靜電夾具相鄰地產生自由電荷，且在該靜電夾具處於該第二組態中時並不與該靜電夾具相鄰地產生自由電荷。 According to a seventh aspect of the present invention, there is provided an apparatus including an electrostatic clamp for clamping a component, and a mechanism for generating free charges adjacent to the electrostatic clamp. The device has: a first configuration in which a voltage with a first polarity is applied to at least one clamp electrode and no component is clamped by the electrostatic clamp; and a second configuration in which a voltage with the first polarity is applied to at least one clamp electrode and no component is clamped by the electrostatic clamp; A voltage of a second opposite polarity is applied to the at least one clamp electrode. The device is configured to be in the first configuration at a first point in time and in the second configuration at a second point in time subsequent to the first point in time. The mechanism for generating free charges is configured to generate free charges adjacent the electrostatic clamp when the electrostatic clamp is in the first configuration, and not when the electrostatic clamp is in the second configuration. Free charges are generated adjacent to the electrostatic clamp.
藉由在該夾具於一第一激勵狀態中經極化時與該靜電夾具相鄰地提供自由電荷，可對截留於該夾具表面上之任何粒子充電。接著，當極化反轉且自由電荷不再存在時，帶電粒子可藉由靜電排斥自夾具表面釋放。靜電夾具之此清潔製程可避免或至少減小與經截留於夾具表面上之粒子相關聯的負面結果。 Any particles trapped on the surface of the clamp can be charged by providing free charges adjacent the electrostatic clamp while the clamp is polarized in a first excited state. Then, when the polarization is reversed and free charges are no longer present, the charged particles can be released from the clamp surface via electrostatic repulsion. This cleaning process of electrostatic clamps can avoid or at least reduce the negative consequences associated with particles trapped on the clamp surface.
該設備可為用於清潔靜電夾具之一設備。 This device can be one of the devices used to clean electrostatic clamps.
可在自該第一組態至該第二組態之一轉變期間與該靜電夾具相鄰地提供一組件。 A component may be provided adjacent the electrostatic clamp during a transition from the first configuration to the second configuration.
藉由在該轉變期間與該靜電夾具相鄰地提供一組件，歸因於極性改變而由該夾具釋放之粒子可由該組件捕捉，而不會污染該設備之其他表面。該組件可被稱作犧牲組件或清潔組件。該組件可包含圖案化器件。該組件之大小可大體上等於在微影操作期間意欲由該靜電夾具夾持的組件之大小。 By providing a component adjacent to the electrostatic clamp during the transition, particles released by the clamp due to the change in polarity can be captured by the component without contaminating other surfaces of the device. This component may be referred to as a sacrificial component or a cleaning component. The assembly may include patterned devices. The size of the component may be substantially equal to the size of the component intended to be held by the electrostatic clamp during lithography operations.
當該夾具處於該第二組態中時，該組件可由該靜電夾具夾 持。亦即，該靜電夾具可經組態以在該夾具處於該第二組態中時夾持該組件。 When the clamp is in the second configuration, the component can be clamped by the electrostatic clamp hold. That is, the electrostatic clamp may be configured to clamp the component when the clamp is in the second configuration.
該設備可具有一第三組態，其中無電壓被施加至該至少一個夾具電極且無組件由該靜電夾具夾持。該設備可經組態為在該第二時間點之後的一第三時間點處於該第三組態中。 The device may have a third configuration in which no voltage is applied to the at least one clamp electrode and no components are clamped by the electrostatic clamp. The device may be configured to be in the third configuration at a third time point after the second time point.
一旦已藉由應用反向極化(在第二組態期間)來釋放粒子，夾具就可返回至中性組態(亦即其中無電壓被施加至夾具電極)。 Once the particles have been released by applying reverse polarization (during the second configuration), the clamp can return to the neutral configuration (that is, where no voltage is applied to the clamp electrodes).
用於產生自由電荷之該機構可經組態以在該靜電夾具處於該第三組態中時與該靜電夾具相鄰地產生自由電荷。 The mechanism for generating free charges may be configured to generate free charges adjacent the electrostatic clamp when the electrostatic clamp is in the third configuration.
一旦已藉由應用反向極化(在第二組態期間)來釋放粒子，夾具就可返回至中性組態(亦即其中無電壓被施加至夾具電極)，且夾具表面上之任何殘餘電荷藉由與夾具相鄰地提供自由電荷來移除。 Once the particles have been released by applying reverse polarization (during the second configuration), the clamp can be returned to the neutral configuration (i.e. where no voltage is applied to the clamp electrodes) and any residual The charge is removed by providing free charge adjacent to the fixture.
在該第三組態中，無組件可被提供為與該靜電夾具相鄰。亦即，該設備可受控制使得在該第三組態中無組件被提供為與該靜電夾具相鄰。 In this third configuration, no components may be provided adjacent the electrostatic clamp. That is, the device may be controlled such that no components are provided adjacent the electrostatic clamp in the third configuration.
該設備可進一步包含經組態以支撐與該靜電夾具相鄰之一組件之一組件交換總成。 The apparatus may further include a component exchange assembly configured to support a component adjacent the electrostatic clamp.
該組件交換總成可經組態以控制該組件與該靜電夾具之間的分離度。 The component exchange assembly can be configured to control the degree of separation between the component and the electrostatic clamp.
該組件交換總成可經組態以在該第一時間點與該第二時間點之間提供與該靜電夾具相鄰之該組件。 The component exchange assembly can be configured to provide the component adjacent the electrostatic clamp between the first point in time and the second point in time.
該組件交換總成可經組態以在該第二時間點與該第三時間點之間自該靜電夾具附近移除該組件。 The component exchange assembly may be configured to remove the component from adjacent the electrostatic clamp between the second point in time and the third point in time.
該靜電夾具可包含經組態以夾持一組件之一夾持區。當一組件被夾持時，可在該夾持區與該組件之間產生一夾持電場。 The electrostatic clamp may include a clamping region configured to clamp a component. When a component is clamped, a clamping electric field can be generated between the clamping area and the component.
當將該夾持電壓施加至該至少一個電極時，可產生該夾持電場。該設備可進一步包含一電壓源。 When the clamping voltage is applied to the at least one electrode, the clamping electric field can be generated. The device may further include a voltage source.
用於與該靜電夾具相鄰地產生自由電荷之該機構可包含一氣體源，及經組態以電離由該氣體源提供之氣體之一電離輻射源。 The mechanism for generating free charges adjacent the electrostatic clamp may include a gas source, and a source of ionizing radiation configured to ionize gas provided by the gas source.
該電離輻射源包含選自由以下各者組成之群組之一源：一EUV源、一VUV源、一軟x射線源及一放射性源。 The ionizing radiation source includes a source selected from the group consisting of an EUV source, a VUV source, a soft x-ray source, and a radioactive source.
亦可提供一種經配置以將一圖案自一圖案化器件投影至一基板上之微影設備。該微影設備可包含根據本發明之該第七態樣之一設備。該靜電夾具可經組態以在一微影操作期間夾持該圖案化器件。 A lithography apparatus configured to project a pattern from a patterned device onto a substrate may also be provided. The lithography apparatus may include an apparatus according to the seventh aspect of the present invention. The electrostatic clamp can be configured to hold the patterned device during a lithography operation.
該微影設備可進一步包含經組態以調節一輻射光束之一照明系統。該靜電夾具可經組態以夾持該圖案化器件，該圖案化器件能夠在該輻射光束之橫截面中向該輻射光束賦予一圖案以形成一經圖案化輻射光束。該微影設備可進一步包含：一基板台，其經建構以固持一基板；及一投影系統，其經組態以將該經圖案化輻射光束投影至該基板上。 The lithography apparatus may further include an illumination system configured to modulate a radiation beam. The electrostatic clamp can be configured to hold the patterned device capable of imparting a pattern to the radiation beam in a cross-section of the radiation beam to form a patterned radiation beam. The lithography apparatus may further include: a substrate stage configured to hold a substrate; and a projection system configured to project the patterned radiation beam onto the substrate.
亦可提供一種包含該微影設備之微影系統。該微影系統可進一步包含經組態以產生該輻射光束之一輻射源。 A lithography system including the lithography equipment can also be provided. The lithography system may further include a radiation source configured to generate the radiation beam.
用於產生自由電荷之該機構可包含選自由以下各者組成之群組之電離輻射之一次級源：一EUV源、一VUV源、一軟x射線源及一放射性源。 The mechanism for generating free charges may include a secondary source of ionizing radiation selected from the group consisting of an EUV source, a VUV source, a soft x-ray source, and a radioactive source.
用於產生自由電荷之該機構可包含該輻射源。該輻射源可為一EUV源。 The mechanism for generating free charges may include the radiation source. The radiation source may be an EUV source.
根據本發明之一第八態樣，提供一種操作一設備之方法，該設備包含一靜電夾具，該靜電夾具包含至少一個夾具電極；及用於與該靜電夾具相鄰地產生自由電荷之一機構。該方法包含：控制該靜電夾具以具有一第一組態，其中在一第一時間點，將具有一第一極性之一電壓施加至該至少一個夾具電極且無組件由該靜電夾具夾持；控制該靜電夾具以具有一第二組態，其中在該第一時間點之後的一第二時間點，將具有與該第一極性相反的一第二極性之一電壓施加至該至少一個夾具電極；控制用於產生自由電荷之該機構以在該夾具處於該第一組態中時與該靜電夾具相鄰地產生自由電荷；及控制用於產生自由電荷之該機構以在該靜電夾具處於該第二組態中時不與該靜電夾具相鄰地產生自由電荷。 According to an eighth aspect of the present invention, there is provided a method of operating a device, the device including an electrostatic clamp including at least one clamp electrode; and a mechanism for generating free charges adjacent to the electrostatic clamp. . The method includes: controlling the electrostatic clamp to have a first configuration, wherein at a first point in time, a voltage having a first polarity is applied to the at least one clamp electrode and no component is clamped by the electrostatic clamp; Controlling the electrostatic clamp to have a second configuration, wherein at a second time point after the first time point, a voltage having a second polarity opposite to the first polarity is applied to the at least one clamp electrode ; controlling the mechanism for generating free charges to generate free charges adjacent the electrostatic clamp when the clamp is in the first configuration; and controlling the mechanism for generating free charges to generate free charges when the electrostatic clamp is in the In the second configuration, no free charges are generated adjacent to the electrostatic clamp.
該方法可進一步包含當該靜電夾具處於該第二組態中時與該靜電夾具相鄰地提供一組件。 The method may further include providing a component adjacent the electrostatic clamp when the electrostatic clamp is in the second configuration.
當該夾具處於該第二組態中時，該組件可由該靜電夾具夾持。 The component may be clamped by the electrostatic clamp when the clamp is in the second configuration.
該方法可進一步包含控制該設備以具有一第三組態，其中在該第二時間點之後的一第三時間點，無電壓被施加至該至少一個夾具電極。 The method may further include controlling the device to have a third configuration, wherein at a third time point after the second time point, no voltage is applied to the at least one clamp electrode.
該方法可進一步包含在該第二時間點與該第三時間點之間自該靜電夾具附近移除該組件。 The method may further include removing the component from adjacent the electrostatic clamp between the second time point and the third time point.
該方法可進一步包含控制用於產生自由電荷之該機構以在該靜電夾具處於該第三組態中時與該靜電夾具相鄰地產生自由電荷。 The method may further include controlling the mechanism for generating free charges to generate free charges adjacent the electrostatic clamp when the electrostatic clamp is in the third configuration.
當然應瞭解，以上結合本發明之該第七態樣之該設備所描述之特徵中的任一者可與本發明之該第八態樣之該方法之特徵組合。 It will of course be understood that any of the features described above in connection with the apparatus of the seventh aspect of the invention may be combined with features of the method of the eighth aspect of the invention.
根據本發明之一第九態樣，提供一種操作一設備之方法，該設備包含具有一第一電極之一靜電夾具，該方法包含：a)與該靜電夾具相鄰地提供一組件；b)控制該靜電夾具以便將一第一夾持電壓提供至該第一電極使得該組件由該靜電夾具夾持；c)量測與該組件之一部分相關聯的一電壓；及d)基於該所量測電壓判定對該第一夾持電壓之一調整。 According to a ninth aspect of the present invention, there is provided a method of operating a device, the device comprising an electrostatic chuck having a first electrode, the method comprising: a) providing a component adjacent to the electrostatic chuck; b) Controlling the electrostatic clamp to provide a first clamping voltage to the first electrode such that the component is clamped by the electrostatic clamp; c) measuring a voltage associated with a portion of the component; and d) based on the measurement The voltage measurement determines the adjustment of one of the first clamping voltages.
該靜電夾具包含一第一夾持電壓被供應至之一第一電極。該第一夾持電壓在該夾具與該組件之間產生一電場使得該組件可在其背面處被夾持至該夾具之一夾持區。該組件亦包含與該背面相反地配置之一正面。該組件可經由尤其在與該夾具相鄰之該背面處的粒子(亦即電子或離子)之靜電吸引而累積電荷，且因此與系統之其他部件相比處於不同的電壓。藉由量測與組件之一部分(例如組件之背面)相關聯之電壓，有可能判定對第一夾持電壓之調整使得與該組件之該部分相關聯的電壓變為零。應瞭解，可依據待加至第一夾持電壓或自第一夾持電壓減去之額外電壓，或作為第一夾持電壓之百分比改變或以如對於熟習此項技術者而言顯而易見之任何其他合適項來判定該調整。藉由判定及應用對第一夾持電壓之調整，可達成組件相對於周圍系統之虛擬接地。結果，可減小或消除電荷(及帶電粒子)至組件之靜電吸引力。組件可為由靜電夾具夾持之圖案化器件(例如倍縮光罩)。然而，應瞭解，組件可為待由夾具夾持之另一組件。 The electrostatic clamp includes a first clamping voltage supplied to a first electrode. The first clamping voltage generates an electric field between the clamp and the component so that the component can be clamped to a clamping area of the clamp at its back surface. The component also includes a front face configured opposite the back face. The component may accumulate charge via electrostatic attraction of particles (ie electrons or ions) particularly at the backside adjacent to the clamp, and therefore be at a different voltage compared to other components of the system. By measuring the voltage associated with a part of the component (eg, the backside of the component), it is possible to determine that the adjustment of the first clamping voltage is such that the voltage associated with that part of the component becomes zero. It should be understood that the voltage may be based on additional voltage to be added to or subtracted from the first clamping voltage, or as a percentage change of the first clamping voltage or in any manner as would be obvious to one skilled in the art. Other appropriate items to determine the adjustment. By determining and applying adjustments to the first clamping voltage, a virtual ground of the component relative to the surrounding system can be achieved. As a result, the electrostatic attraction of charges (and charged particles) to the component can be reduced or eliminated. The component may be a patterned device (eg, a reticle) held by an electrostatic clamp. However, it should be understood that the component may be another component to be clamped by the clamp.
該方法可進一步包含：b1)在組件由靜電夾具夾持時，將該組件曝光至輻射；b2)控制靜電夾具使得自該靜電夾具釋放該組件；及b3)自該靜電夾具附近移除該組件。 The method may further comprise: b1) exposing the component to radiation while the component is clamped by the electrostatic chuck; b2) controlling the electrostatic chuck to release the component from the electrostatic chuck; and b3) removing the component from adjacent the electrostatic chuck .
以此方式，可在離線製程中進行電壓量測。在此實施中，組件由靜電夾具夾持且曝光至輻射。在曝光期間，電荷可沈積於組件之背 面(亦即，組件之夾持至夾具之側面)上。當移除夾持電壓以便釋放組件時，經累積電荷保持於該組件之表面上。可自夾具附近移除組件以接著量測相關聯電壓。可接著基於經量測電壓判定對第一夾持電壓之任何調整。 In this way, voltage measurements can be performed in offline processes. In this implementation, the assembly is clamped by electrostatic clamps and exposed to radiation. During exposure, charges can be deposited on the back of the component surface (that is, the side of the clamp to which the component is clamped). When the clamping voltage is removed to release the component, the accumulated charge remains on the surface of the component. Components can be removed from the vicinity of the fixture to then measure the associated voltage. Any adjustments to the first clamping voltage may then be determined based on the measured voltage.
該方法可進一步包含：e)根據經判定調整來調整第一夾持電壓；及f)重複步驟a)至c)以便驗證該調整。 The method may further comprise: e) adjusting the first clamping voltage based on the determined adjustment; and f) repeating steps a) to c) to verify the adjustment.
一旦已判定對第一夾持電壓之調整，就可重複步驟a)至c)以便驗證該調整成功地將與組件相關聯之電壓減小為零伏特。若仍發現存在與組件之部分相關聯之電壓，則可執行進一步調整及驗證步驟。結果，可減輕在先前經夾持組件之卸載期間與電壓放大相關聯的問題，此係由於在曝光之後，無淨電荷將保持於虛擬接地之組件上。 Once the adjustment to the first clamping voltage has been determined, steps a) through c) can be repeated to verify that the adjustment successfully reduced the voltage associated with the component to zero volts. If voltage is still found to be associated with parts of the component, further adjustments and verification steps can be performed. As a result, problems associated with voltage amplification during unloading of previously clamped components may be mitigated since no net charge will remain on the virtually grounded component after exposure.
該方法可進一步包含：在重複步驟a)至c)之後，基於經量測電壓判定對第一夾持電壓之進一步調整。可重複量測及調整製程複數次。可重複量測及調整製程直至與組件之一部分相關聯之電壓滿足預定準則(例如其在零伏特之預定容差內)。 The method may further comprise: after repeating steps a) to c), determining further adjustment of the first clamping voltage based on the measured voltage. The measurement and adjustment process can be repeated multiple times. The measurement and adjustment process can be repeated until the voltage associated with a portion of the component meets a predetermined criterion (eg, it is within a predetermined tolerance of zero volts).
可使用另一組件來執行步驟a)至c)之重複。詳言之，在一些實施中，可使用與用於初始量測相同之組件來執行驗證步驟。然而，在其他實施中，可需要使用未用於初始量測之另一組件。 Another component may be used to perform the repetition of steps a) to c). Specifically, in some implementations, the verification step may be performed using the same components used for the initial measurements. However, in other implementations, it may be desirable to use another component that was not used for the initial measurement.
該方法可進一步包含：在判定對第一夾持電壓之調整之後，根據該經判定調整來調整第一夾持電壓；及量測與組件之該部分相關聯之電壓。 The method may further include, after determining an adjustment to the first clamping voltage, adjusting the first clamping voltage based on the determined adjustment; and measuring a voltage associated with the portion of the component.
作為對離線量測製程之替代方案，可在線執行量測，亦即在組件被夾持時。在方法之此實施中，在量測步驟之後立即判定調整，而不釋放組件及自夾具移除組件。可需要在組件保持被夾持於適當位置時執 行調整及後續量測步驟。以此方式，可減少處理時間，此係由於不需要自夾具移除組件以便量測相關聯電壓。另外，可週期性地重複該方法。替代地或另外，該方法可經實施為連續回饋迴路，其中監視與組件相關聯之電壓且結果自動調整夾持電壓。 As an alternative to offline measurement processes, measurements can be performed online, that is, while the component is clamped. In this implementation of the method, the adjustment is determined immediately after the measurement step without releasing and removing the component from the fixture. May need to be performed while the component remains clamped in place Perform adjustments and subsequent measurement steps. In this way, processing time can be reduced since components do not need to be removed from the fixture in order to measure the associated voltage. Additionally, the method can be repeated periodically. Alternatively or additionally, the method may be implemented as a continuous feedback loop, where the voltage associated with the component is monitored and the clamping voltage is automatically adjusted as a result.
該靜電夾具可進一步包含一第二電極，且該方法可進一步包含：基於經量測電壓判定對待供應至該第二電極之第二夾持電壓之調整。 The electrostatic clamp may further include a second electrode, and the method may further include determining an adjustment of the second clamping voltage to be supplied to the second electrode based on the measured voltage.
該第一夾持電壓與該第二夾持電壓可具有不同值。詳言之，該第一夾持電壓與該第二夾持電壓可具有不同極性。舉例而言，第一夾持電壓可大致為+1kV至10kV，且第二夾持電壓可大致為-1kV至10kV。詳言之，第一夾持電壓可大致為+2kV且第二夾持電壓可約為-2kV。當然，應瞭解，亦可存在第一夾持電壓與第二夾持電壓之絕對值之差。此外，應瞭解，對第一及/或第二夾持電壓之經判定調整可為對第一夾持電壓之調整，或對第二夾持電壓準之調整，或對第一及第二夾持電壓兩者之調整。另外，該經判定調整可例如為第一與第二夾持電壓之間的差之調整，或對第一及第二夾持電壓之平均值之調整。 The first clamping voltage and the second clamping voltage may have different values. In detail, the first clamping voltage and the second clamping voltage may have different polarities. For example, the first clamping voltage may be approximately +1 kV to 10 kV, and the second clamping voltage may be approximately -1 kV to 10 kV. In detail, the first clamping voltage may be approximately +2kV and the second clamping voltage may be approximately -2kV. Of course, it should be understood that there may also be a difference in absolute values of the first clamping voltage and the second clamping voltage. Furthermore, it should be understood that the determined adjustment of the first and/or second clamping voltage may be an adjustment of the first clamping voltage, an adjustment of the second clamping voltage level, or an adjustment of the first and second clamping voltage levels. Adjustment of holding voltage. In addition, the determined adjustment may be, for example, an adjustment of the difference between the first and second clamping voltages, or an adjustment of the average value of the first and second clamping voltages.
根據本發明之一第十態樣，提供一種用於使一組件虛擬接地之系統，該系統包含：一設備，其包含經組態以夾持該組件之一靜電夾具，該靜電包含經組態以接收一第一夾持電壓之一第一電極；一電壓監視器，其經組態以量測與該組件之一部分相關聯之一電壓；及一演算單元，其經組態以基於該經量測電壓判定對該第一夾持電壓之一調整。 According to a tenth aspect of the present invention, a system for virtually grounding a component is provided. The system includes: a device including an electrostatic clamp configured to clamp the component, the static electricity including the configured a first electrode to receive a first clamping voltage; a voltage monitor configured to measure a voltage associated with a portion of the component; and a computing unit configured to measure a voltage based on the The measured voltage determines an adjustment of the first clamping voltage.
該系統可進一步包含經組態以支撐該組件之一支撐總成，其中該支撐總成包含該電壓監視器。舉例而言，該支撐總成可為經組態以 將該組件朝向或遠離該夾具附近輸送之一交換總成。 The system may further include a support assembly configured to support the component, wherein the support assembly includes the voltage monitor. For example, the support assembly may be configured to Transport the assembly toward or away from a swap assembly near the fixture.
該靜電夾具可包含經組態以接收一第二夾持電壓之一第二電極，且該演算單元亦可經組態以基於該經量測電壓判定對該第二夾持電壓之一調整。 The electrostatic clamp may include a second electrode configured to receive a second clamping voltage, and the computing unit may also be configured to determine an adjustment to the second clamping voltage based on the measured voltage.
該第一夾持電壓與該第二夾持電壓可具有不同值。 The first clamping voltage and the second clamping voltage may have different values.
該電壓監視器可為一靜電伏特計。 The voltage monitor can be an electrostatic voltmeter.
當然，應瞭解，以上結合本發明之第九態樣之方法所描述之特徵中的任一者可與本發明之第十態樣之系統之特徵組合。 Of course, it should be understood that any of the features described above in conjunction with the method of the ninth aspect of the invention may be combined with the features of the system of the tenth aspect of the invention.
另外，應瞭解，以上結合本發明之第一至第十態樣中之任一者所描述的特徵中之任一者可與在上文所描述態樣之不同態樣之內容背景中所描述的特徵組合。 Additionally, it will be understood that any of the features described above in connection with any of the first to tenth aspects of the invention may be described in the context of different aspects of the above described aspects. combination of characteristics.
10:琢面化場鏡面器件 10: Faceted field mirror device
11:琢面化光瞳鏡面器件 11: Faceted pupil mirror device
13:鏡面 13:Mirror
14:鏡面 14:Mirror
100:靜電夾具 100:Electrostatic clamp
102:夾具本體 102: Fixture body
104A:夾具電極/初級電極/負偏壓電極 104A: Clamp electrode/primary electrode/negative bias electrode
104B:夾具電極/初級電極 104B: Clamp electrode/primary electrode
104C:夾具電極/初級電極 104C: Clamp electrode/primary electrode
104D:夾具電極/初級電極 104D: Clamp electrode/primary electrode
106:瘤節 106: Tumor knot
108:區/夾具突起部/夾具耳狀物 108: Area/Clamp Protrusion/Clamp Ear
110:區/夾具突起部/夾具耳狀物 110: Area/Clamp Protrusion/Clamp Ear
114A:次級電極/靜電夾具電極 114A: Secondary electrode/electrostatic clamp electrode
114B:次級電極/靜電夾具電極 114B: Secondary electrode/electrostatic clamp electrode
114C:次級電極/靜電夾具電極 114C: Secondary electrode/electrostatic clamp electrode
114D:次級電極/靜電夾具電極 114D: Secondary electrode/electrostatic clamp electrode
120:基板 120:Substrate
122:第一平面表面 122: First plane surface
124:第二平面表面 124: Second plane surface
126:導電塗層 126:Conductive coating
128:導電塗層/正極化塗層/導電表面 128: Conductive coating/anodized coating/conductive surface
140:遮蔽葉片 140:Shading blades
142:遮蔽葉片 142:Shading blades
144:遮蔽葉片 144:Shading blades
146:遮蔽葉片 146:Shading blades
150:交換總成 150:Exchange assembly
152:交換器件 152:Switching device
154:支撐結構 154:Support structure
156:突起部 156:Protrusion
160:清潔倍縮光罩 160: Clean the zoom mask
162:本體 162:Ontology
164:導電層 164: Conductive layer
166:絕緣層 166:Insulation layer
180:電壓監視器 180:Voltage monitor
200:步驟 200: steps
202:步驟 202:Step
204:步驟 204:Step
206:步驟 206:Step
208:步驟 208:Step
210:步驟 210: Step
212:步驟 212: Step
300:步驟 300: steps
302:步驟 302: Step
304:步驟 304: Step
306:步驟 306: Step
308:步驟 308:Step
A-A':線 A-A': line
b:間隙/分離度 b: gap/separation
B:EUV輻射光束 B: EUV radiation beam
B':經圖案化EUV輻射光束 B': Patterned EUV radiation beam
B-B':線 B-B': line
Cb:可變電容/電容器 C b : variable capacitance/capacitor
Cd:夾具電容/電容器/電容器 C d : fixture capacitance/capacitor/capacitor
Cg:可變電容/電容器 C g : variable capacitance/capacitor
Cr:固定電容/電容器 C r : fixed capacitor/capacitor
F:場線 F: field line
g:間隙/分離度/距離 g: gap/separation/distance
IL:照明系統 IL: lighting system
LA:微影設備 LA: Lithography equipment
MA:圖案化器件 MA: Patterned device
MT:支撐結構 MT: support structure
P:電漿 P:plasma
P1:粒子 P1: particles
P2:粒子 P2: particles
Q1:正電荷 Q1: Positive charge
Q2:負電荷 Q2: Negative charge
QA:掩蔽電荷 QA: masking charge
QB:掩蔽電荷 QB: masking charge
QC:掩蔽電荷 QC: masking charge
QD:掩蔽電荷 QD: masking charge
Qb:電荷/電荷源 Q b : charge/charge source
Qf:電荷/電荷源 Q f :charge/charge source
Qs:電荷/電荷源 Q s : charge/charge source
S:次級源/次級電離源/VUV源 S: Secondary source/secondary ionization source/VUV source
SO:輻射源/EUV源 SO: Radiation source/EUV source
TA:時段/曝光叢發 T A : time period/exposure burst
TA':曝光前時段/曝光前叢發 T A ': pre-exposure period/pre-exposure burst
TA":曝光後時段/曝光後叢發 T A ": post-exposure period/post-exposure cluster
TB:時段/曝光叢發 T B : time period/exposure burst
TC:時段/曝光叢發 T C : time period/exposure burst
TD:時段/曝光叢發 T D : time period/exposure burst
t0:時間 t 0 : time
t1:時間 t1 : time
t2:時間 t 2 : time
t3:時間 t3 : time
t4:時間 t 4 : time
t5:時間 t 5 : time
t6:時間 t6 : time
t11:時間 t 11 : time
t12:時間 t 12 : time
t20:時間 t 20 : time
t21:時間 t 21 : time
t22:時間 t 22 : time
t23:時間 t 23 : time
t24:時間 t 24 : time
t25:時間 t 25 : time
t26:時間 t 26 : time
t27:時間 t 27 : time
t28:時間 t 28 : time
V:區 V:area
V1:粒子 V1:Particles
Vb:電壓 V b :voltage
Vd:電壓 Vd : voltage
Vg:電壓 Vg : voltage
Vr:電壓 V r :voltage
+VC:夾持電壓 +V C : clamping voltage
-VC:電壓 -V C : voltage
W:基板/區 W: substrate/area
WT:基板台 WT: substrate table
W1:粒子 W1: particles
W2:正電荷 W2: Positive charge
X:第一區 X: Area 1
X1:粒子 X1:particle
Y:區 Y:District
Y1:粒子 Y1:particle
Z:區 Z:Zone
Z1:粒子 Z1:particle
Z2:負電荷 Z2: negative charge
現在將僅作為實例參看隨附示意性圖式來描述本發明之實施例，在該等圖式中：- 圖1描繪包含微影設備及輻射源之微影系統；- 圖2a至圖2c分別以橫截面圖、平面圖及截面圖描繪在圖1中所展示之微影設備內使用的靜電夾具；- 圖3描繪在曝光至EUV輻射期間之圖2之靜電夾具周圍的電漿密度之模擬；- 圖4a及圖4b分別描繪先前技術微影設備之曝光序列及夾具極化序列；- 圖5a及圖5b分別描繪根據本發明之一實施例的微影設備之曝光序列及夾具極化序列； 圖6a及圖6b分別描繪根據本發明之一實施例的微影設備之替代曝光序列及夾具極化序列；圖7a及圖7b分別描繪根據本發明之一實施例的微影設備之另一替代曝光序列及夾具極化序列；圖8a至圖8c分別以橫截面圖、平面圖及截面圖描繪在根據本發明之替代實施例之微影設備內使用的靜電夾具；圖9a及圖9b描繪在圖案化器件卸載製程期間在根據本發明之實施例之微影設備內使用的靜電夾具及圖案化器件；圖10描繪在圖案化器件卸載製程期間在根據本發明之實施例之微影設備內使用的靜電夾具及圖案化器件之移動序列；圖11描繪在根據本發明之實施例之微影設備內使用的靜電夾具及圖案化器件之等效電路模型；圖12a至圖12c描繪在圖10之移動序列期間之圖9之等效電路的模擬特性；圖13描繪在根據本發明之實施例之微影設備內使用的靜電夾具及圖案化器件之等效電路模型；圖14描繪在根據本發明之實施例之微影設備內使用的靜電夾具及圖案化器件；圖15a至圖15e描繪用於在根據本發明之實施例之微影設備內使用的靜電夾具之清潔製程；圖16描繪根據一實施例的用於提供圖案化器件之虛擬接地之方法的流程圖；圖17描繪根據另一實施例的用於提供圖案化器件之虛擬接地之替代方法的流程圖；及 圖18描繪具有包含根據本發明之實施例之電壓監視器之支撐總成的靜電夾具及圖案化器件。 Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which: - Figure 1 depicts a lithography system comprising a lithography apparatus and a radiation source; - Figures 2a to 2c respectively - Figure 3 depicts a simulation of the plasma density around the electrostatic clamp of Figure 2 during exposure to EUV radiation; - Figure 3 depicts a simulation of the plasma density around the electrostatic clamp of Figure 2 during exposure to EUV radiation; - Figures 4a and 4b respectively depict the exposure sequence and the clamp polarization sequence of the lithography equipment of the prior art; - Figures 5a and 5b respectively depict the exposure sequence and the clamp polarization sequence of the lithography equipment according to one embodiment of the present invention; Figures 6a and 6b respectively depict an alternative exposure sequence and a fixture polarization sequence of a lithography apparatus according to an embodiment of the invention; Figures 7a and 7b respectively depict another alternative of a lithography apparatus according to an embodiment of the invention. Exposure sequence and clamp polarization sequence; Figures 8a to 8c depict an electrostatic clamp used in a lithography apparatus according to an alternative embodiment of the invention in a cross-sectional view, a plan view and a cross-sectional view respectively; Figures 9a and 9b depict a pattern An electrostatic clamp and a patterned device used in a lithography apparatus according to an embodiment of the invention during a patterned device unloading process; FIG. 10 depicts an electrostatic clamp used in a lithography apparatus according to an embodiment of the invention during a patterned device unloading process. Movement sequence of the electrostatic clamp and the patterning device; Figure 11 depicts an equivalent circuit model of the electrostatic clamp and the patterning device used in a lithography apparatus according to an embodiment of the present invention; Figures 12a to 12c depict the movement in Figure 10 Simulation characteristics of the equivalent circuit of Figure 9 during the sequence; Figure 13 depicts an equivalent circuit model of an electrostatic clamp and a patterning device used in a lithography apparatus according to an embodiment of the present invention; Figure 14 depicts an equivalent circuit of The electrostatic clamp and patterning device used in the lithography equipment of the embodiment; Figures 15a to 15e depict a cleaning process for the electrostatic clamp used in the lithography equipment according to the embodiment of the present invention; Figure 16 depicts an implementation 17 depicts a flowchart of an alternative method for providing a virtual ground for a patterned device according to another embodiment; and Figure 18 depicts an electrostatic clamp and patterned device with a support assembly including a voltage monitor according to an embodiment of the present invention.
圖1展示包含輻射源SO及微影設備LA之微影系統。輻射源SO經組態以產生EUV輻射光束B且將EUV輻射光束B供應至微影設備LA。微影設備LA包含照明系統IL、經組態以支撐圖案化器件MA(例如光罩)之支撐結構MT、投影系統PS及經組態以支撐基板W之基板台WT。 Figure 1 shows a lithography system including a radiation source SO and a lithography apparatus LA. Radiation source SO is configured to generate EUV radiation beam B and supply EUV radiation beam B to lithography apparatus LA. Lithography apparatus LA includes an illumination system IL, a support structure MT configured to support a patterned device MA (eg, a photomask), a projection system PS, and a substrate table WT configured to support a substrate W.
照明系統IL經組態以在EUV輻射光束B入射於圖案化器件MA上之前調節EUV輻射光束B。另外，照明系統IL可包括琢面化場鏡面器件10及琢面化光瞳鏡面器件11。琢面化場鏡面器件10及琢面化光瞳鏡面器件11一起向EUV輻射光束B提供所要橫截面形狀及所要強度分佈。除了琢面化場鏡面器件10及琢面化光瞳鏡面器件11以外或代替琢面化場鏡面器件10及琢面化光瞳鏡面器件11，照明系統IL亦可包括其他鏡面或器件。 The illumination system IL is configured to condition the EUV radiation beam B before the EUV radiation beam B is incident on the patterned device MA. In addition, the illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11 . The faceted field mirror device 10 and the faceted pupil mirror device 11 together provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. In addition to or instead of the faceted field mirror device 10 and the faceted pupil mirror device 11 , the illumination system IL may also include other mirrors or devices.
在由此調節之後，EUV輻射光束B與圖案化器件MA相互作用。作為此相互作用之結果，產生經圖案化EUV輻射光束B'。投影系統PS經組態以將經圖案化EUV輻射光束B'投影至基板W上。出於彼目的，投影系統PS可包含經組態以將經圖案化EUV輻射光束B'投影至由基板台WT固持之基板W上的複數個鏡面13、14。投影系統PS可將縮減因數應用於經圖案化EUV輻射光束B'，因此形成特徵小於圖案化器件MA上之對應特徵的影像。舉例而言，可應用為4或8之縮減因數。儘管投影系統PS被說明為僅具有圖1中之兩個鏡面13、14，但投影系統PS可包括不同數目個鏡面(例如，六個或八個鏡面)。 After this conditioning, the EUV radiation beam B interacts with the patterned device MA. As a result of this interaction, a patterned EUV radiation beam B' is produced. Projection system PS is configured to project patterned EUV radiation beam B' onto substrate W. For this purpose, the projection system PS may comprise a plurality of mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate table WT. Projection system PS can apply a reduction factor to patterned EUV radiation beam B', thereby forming an image with features that are smaller than corresponding features on patterned device MA. For example, a reduction factor of 4 or 8 may be applied. Although projection system PS is illustrated as having only two mirrors 13, 14 in Figure 1, projection system PS may include a different number of mirrors (eg, six or eight mirrors).
基板W可包括先前形成之圖案。在此狀況下，微影設備LA 使由經圖案化EUV輻射光束B'形成之影像與先前形成於基板W上之圖案對準。 The substrate W may include previously formed patterns. In this case, the lithography equipment LA The image formed by the patterned EUV radiation beam B' is aligned with the pattern previously formed on the substrate W.
可在輻射源SO中、在照明系統IL中及/或在投影系統PS中提供相對真空，亦即在充分地低於大氣壓力之壓力下之少量氣體(例如氫氣)。 A relative vacuum, ie a small amount of gas (eg hydrogen) at a pressure well below atmospheric pressure, may be provided in the radiation source SO, in the illumination system IL and/or in the projection system PS.
輻射源SO可為雷射產生電漿(laser produced plasma，LPP)源、放電產生電漿(discharge produced plasma，DPP)源、自由電子雷射(free electron laser，FEL)或能夠產生EUV輻射之任何其他輻射源。 The radiation source SO may be a laser produced plasma (LPP) source, a discharge produced plasma (DPP) source, a free electron laser (FEL) or anything that can produce EUV radiation. Other sources of radiation.
圖2a更詳細地展示支撐結構MT之截面。該截面係在x平面中，在所展示定向中在z方向上豎直地延伸且在y方向上水平地延伸。支撐結構MT包含經組態以在微影操作期間夾持圖案化器件MA之靜電夾具100。夾具100包含夾具本體102，及安置於夾具本體102內之夾具電極104A至104D。電極104A至104D藉由介電塗層與夾具100之大體上平面夾持表面分離。瘤節106自夾具本體102之夾持表面突起，且用以將經夾持圖案化器件MA與夾具本體102分離。瘤節106可例如具有約10μm之高度，且可集體地覆蓋夾具100之表面的約1%。應瞭解，為簡單起見省略了夾具100之許多特徵(例如配線、額外電極)。 Figure 2a shows a cross-section of the support structure MT in more detail. The section is in the x-plane, extending vertically in the z-direction and horizontally in the y-direction in the orientation shown. The support structure MT includes an electrostatic clamp 100 configured to clamp the patterned device MA during lithography operations. The clamp 100 includes a clamp body 102 and clamp electrodes 104A to 104D disposed in the clamp body 102 . Electrodes 104A-104D are separated from the generally planar clamping surface of clamp 100 by a dielectric coating. The knob 106 protrudes from the clamping surface of the clamp body 102 and is used to separate the clamped patterned device MA from the clamp body 102 . Nodules 106 may, for example, have a height of approximately 10 μm, and may collectively cover approximately 1% of the surface of clamp 100 . It should be appreciated that many features of clamp 100 (eg, wiring, additional electrodes) have been omitted for simplicity.
圖案化器件MA包含基板120，該基板通常可由具有超低熱膨脹係數之材料(例如由Corning製造之ULE®，或由Schott AG製造之Zerodur®)形成。基板120係大體上平面的，且具有彼此相對之第一平面表面122及第二平面表面124。在使用中(例如如圖1中所展示)，第一表面122經組態以反射輻射光束B，且致使圖案被賦予至光束B。詳言之，第一表面122之區可經圖案化以便致使輻射光束B變得圖案化。第一表面之圖 案化區具備導電塗層126。 The patterned device MA includes a substrate 120, which may typically be formed from a material with an ultra-low coefficient of thermal expansion (such as ULE® manufactured by Corning, or Zerodur® manufactured by Schott AG). The substrate 120 is generally planar and has a first planar surface 122 and a second planar surface 124 that are opposite to each other. In use (eg, as shown in FIG. 1 ), first surface 122 is configured to reflect radiation beam B and cause a pattern to be imparted to beam B. In particular, regions of first surface 122 may be patterned so as to cause radiation beam B to become patterned. Picture of the first surface The cased area is provided with a conductive coating 126 .
為了使靜電夾具100能夠夾持圖案化器件MA，第二表面124具備通常覆蓋大多數第二表面124之導電塗層128。 To enable the electrostatic clamp 100 to clamp the patterned device MA, the second surface 124 is provided with a conductive coating 128 that generally covers most of the second surface 124 .
應理解，靜電夾具100可使用大約幾kV之電壓以便夾持圖案化器件MA。舉例而言，夾具100可為雙極靜電夾具，其中電極104A至104D之第一子集102A、102C連接至約+1…10kV(例如+2kV)之電壓供應件(圖中未繪示)，且電極104A至104D之第二子集102B、102D連接至約-1…10kV(例如-2kV)之電壓供應件。因而，可在夾具100與圖案化器件MA之間建立高電場，從而致使圖案化器件MA被吸引至夾具100。詳言之，在與電極104A至104D相鄰的導電塗層128之區中誘發電荷，其具有與所施加電壓相反之正負號，且在橫越夾具100及圖案化器件MA之各個位置處之相反電荷之間建立吸引力。經組態以支撐圖案化器件MA之夾具100之區可被稱作支撐區。此外，當該夾具經操作以夾持圖案化器件MA時，經組態以產生夾持力之夾具之區可被稱作夾持區。 It should be understood that the electrostatic clamp 100 may use a voltage of approximately several kV in order to clamp the patterned device MA. For example, the clamp 100 may be a bipolar electrostatic clamp in which the first subset 102A, 102C of the electrodes 104A to 104D are connected to a voltage supply (not shown) of approximately +1...10kV (eg, +2kV), And the second subset 102B, 102D of the electrodes 104A to 104D are connected to a voltage supply of approximately -1...10kV (eg -2kV). Thus, a high electric field may be established between the clamp 100 and the patterned device MA, causing the patterned device MA to be attracted to the clamp 100 . In particular, charges are induced in the regions of conductive coating 128 adjacent electrodes 104A-104D that have the opposite sign of the applied voltage and at various locations across fixture 100 and patterned device MA. An attraction is established between opposite charges. The area of the clamp 100 configured to support the patterned device MA may be referred to as a support area. Additionally, the region of the clamp configured to generate a clamping force when the clamp is operated to clamp the patterned device MA may be referred to as a clamping region.
遮蔽葉片140、142與圖案化器件MA相鄰地提供。遮蔽葉片140、142經組態以在曝光序列期間選擇性地遮蔽圖案化器件MA以免於輻射光束B影響。詳言之，遮蔽葉片140、142可在y方向上(亦即，在圖2a中左右)移動以便在曝光期間使輻射光束B橫越圖案化器件MA之表面進行掃描。此外，遮蔽葉片140、142可在y方向上朝向及遠離彼此移動以向圖案化器件MA提供不同程度之遮蔽。舉例而言，遮蔽葉片140、142可封閉以遮擋整個圖案化器件MA，或部分封閉以允許輻射穿過窄隙縫。 Masking blades 140, 142 are provided adjacent to the patterned device MA. Shielding blades 140, 142 are configured to selectively shield patterned device MA from radiation beam B during the exposure sequence. In detail, the masking blades 140, 142 are movable in the y direction (ie, left and right in Figure 2a) to scan the radiation beam B across the surface of the patterned device MA during exposure. Additionally, the shielding blades 140, 142 can move toward and away from each other in the y-direction to provide varying degrees of shielding to the patterned device MA. For example, the shielding blades 140, 142 may be closed to shield the entire patterned device MA, or partially closed to allow radiation to pass through a narrow aperture.
一般而言，應理解，遮蔽葉片140、142可用以調變入射於圖案化器件MA上之輻射之總劑量。該等葉片140、142可例如在z方向上 與圖案化器件間隔開約5mm至10mm(例如10mm)。 In general, it is understood that the shielding blades 140, 142 can be used to modulate the total dose of radiation incident on the patterned device MA. The blades 140, 142 may, for example, be oriented in the z-direction Separate approximately 5mm to 10mm (eg 10mm) from the patterned device.
圖2b以平面圖展示夾具100(與圖2a中所展示之橫截面相比)。該平面圖係在z平面中，在所展示定向中在x方向上豎直地延伸且在y方向上水平地延伸。圖2a之橫截面係沿著圖2b中所展示之線A-A'截取。 Figure 2b shows the clamp 100 in plan view (compared to the cross-section shown in Figure 2a). The plan view is in the z-plane, extending vertically in the x-direction and horizontally in the y-direction in the orientation shown. The cross-section of Figure 2a is taken along line AA' shown in Figure 2b.
電極104A至104D各自具有矩形形狀，且經配置使得大體平行於彼此。在此配置中，所說明之四個電極各自跨越經夾持圖案化器件MA在x方向上之寬度，且各自覆蓋圖案化器件MA在y方向上之長度的約四分之一。在圖2b中，圖案化器件MA之位置係由虛線指示。遮蔽葉片140、142以具有點線之輪廓展示。 Electrodes 104A through 104D each have a rectangular shape and are configured so as to be generally parallel to each other. In this configuration, the four electrodes illustrated each span the width of the clamped patterned device MA in the x-direction and each cover approximately one-quarter of the length of the patterned device MA in the y-direction. In Figure 2b, the position of the patterned device MA is indicated by the dotted line. The shielding blades 140, 142 are shown in outline with dotted lines.
靜電夾具100進一步可包含區108及110，該等區在圖2b中所展示之定向中自靜電夾具100之上部側及下部側突起(但在圖2a中所展示之截面圖中並不可見)。該等突起部108、110大體上在靜電夾具100之平面中且因此並不在如圖2a中所展示之靜電夾具本體102之上方或下方進一步突起。該等突起部108、110可被稱作夾具「耳狀物」。 The electrostatic clamp 100 may further include regions 108 and 110 that protrude from the upper and lower sides of the electrostatic clamp 100 in the orientation shown in Figure 2b (but are not visible in the cross-sectional view shown in Figure 2a) . The protrusions 108, 110 are generally in the plane of the electrostatic chuck 100 and therefore do not protrude further above or below the electrostatic chuck body 102 as shown in Figure 2a. These protrusions 108, 110 may be referred to as the clamp "ears".
突起部108包括次級電極114A及114B。突起部110包含次級電極114C及114D。電極104A至104D中之每一者具有一對應的次級電極114A至114D。電極104A至104D及對應的次級電極114A至114D中之每一者電連接在一起。亦即，電極104A電連接至114A，等等(但未繪示此等連接)。然而，如圖2b中可見，突起部108、110延伸超出經夾持圖案化器件MA之周邊，且因此並不貢獻於靜電夾具100與圖案化器件MA之間的夾持力。突起部108、110因此可被稱作夾具之非夾持區。 Protrusion 108 includes secondary electrodes 114A and 114B. Protruding portion 110 includes secondary electrodes 114C and 114D. Each of electrodes 104A-104D has a corresponding secondary electrode 114A-114D. Each of electrodes 104A-104D and corresponding secondary electrodes 114A-114D are electrically connected together. That is, electrode 104A is electrically connected to 114A, and so on (but these connections are not shown). However, as can be seen in Figure 2b, the protrusions 108, 110 extend beyond the perimeter of the clamped patterned device MA, and therefore do not contribute to the clamping force between the electrostatic clamp 100 and the patterned device MA. The protrusions 108, 110 may therefore be referred to as the non-clamping areas of the clamp.
次級電極114A至114D提供用以將電壓供應件連接至初級電極104A至104D之方便的方式。應理解，為了改良成像效能，維持夾具 100之扁平度係合乎需要的。然而，在一些情況下，提供至夾具電極104A至104D之外部電連接可導致夾具扁平度之失真。因而，藉由提供夾具本體(如上文所描述)內之電極之間的內部連接，可對次級電極114A至114D進行外部連接(圖中未繪示)，而不干涉夾具100之支撐圖案化器件MA之決定性區。此可改良在成像操作期間之圖案化器件MA之總體扁平度。外部連接可包含連接至由次級電極114A至114D提供之接點的引線(圖中未繪示)。該等引線可連接至經組態以根據需要供應夾持電壓之電壓源(圖中未繪示)。 Secondary electrodes 114A to 114D provide a convenient way to connect a voltage supply to primary electrodes 104A to 104D. It should be understood that in order to improve imaging performance, maintaining the fixture A flatness of 100 is desirable. However, in some cases, external electrical connections provided to clamp electrodes 104A-104D can cause distortion of clamp flatness. Thus, by providing internal connections between electrodes within the clamp body (as described above), external connections (not shown) can be made to secondary electrodes 114A through 114D without interfering with the support patterning of clamp 100 The decisive area of the device MA. This can improve the overall flatness of the patterned device MA during imaging operations. External connections may include leads (not shown) connected to contacts provided by secondary electrodes 114A-114D. The leads can be connected to a voltage source (not shown) configured to supply clamping voltage as needed.
圖2c展示夾具100在y平面中在橫截面中的側向圖。此所說明圖在x方向上豎直地延伸且在z方向上水平地延伸。該橫截面係沿著圖2b中所展示之線B-B'截取。因此，僅可看到電極104B以及次級電極114B及114C。可看到突起部108、110相比於圖案化器件MA在x方向上進一步延伸。 Figure 2c shows a side view of the clamp 100 in cross section in the y-plane. This illustrated figure extends vertically in the x-direction and horizontally in the z-direction. The cross-section is taken along line BB' shown in Figure 2b. Therefore, only electrode 104B and secondary electrodes 114B and 114C are visible. It can be seen that the protrusions 108, 110 extend further in the x-direction than the patterned device MA.
額外遮蔽葉片144、146與圖案化器件MA相鄰地提供。遮蔽葉片144、146經組態以在曝光序列期間選擇性地遮蔽圖案化器件MA以免於輻射光束B影響。詳言之，遮蔽葉片144、146可在x方向上移動以便控制輻射光束B之寬度。舉例而言，此控制可用以調適微影設備以實現不同大小之晶粒曝光，且與葉片140、142一起調變入射於圖案化器件MA上之輻射之總劑量。該等葉片144、146可例如在z方向上與圖案化器件間隔開約5mm至10mm(例如6mm)。 Additional masking blades 144, 146 are provided adjacent the patterned device MA. Shielding blades 144, 146 are configured to selectively shield patterned device MA from radiation beam B during the exposure sequence. In detail, the shielding blades 144, 146 are movable in the x-direction in order to control the width of the radiation beam B. For example, this control may be used to adapt the lithography apparatus to achieve exposure of different sized dies and, together with the blades 140, 142, to modulate the total dose of radiation incident on the patterned device MA. The blades 144, 146 may be, for example, spaced apart from the patterned device by approximately 5 mm to 10 mm (eg, 6 mm) in the z-direction.
應理解，在正常使用中，電極104A至104D係由上覆圖案化器件MA掩蔽。然而，次級電極114A至114D並未以相同方式被掩蔽。此係歸因於圖案化器件MA並不在次級電極114A至114D上方延伸(如在圖 2b及圖2c中最佳地所見)。當然，應理解，次級電極114A至114D以與初級電極104A至104D相同之方式與夾具表面絕緣。 It should be understood that in normal use, electrodes 104A-104D are masked by the overlying patterned device MA. However, secondary electrodes 114A to 114D are not masked in the same manner. This is due to the fact that the patterned devices MA do not extend over the secondary electrodes 114A-114D (as shown in FIG. 2b and best seen in Figure 2c). Of course, it should be understood that secondary electrodes 114A-114D are insulated from the clamp surface in the same manner as primary electrodes 104A-104D.
在使用期間，規則地切換施加至電極104A至104D之電壓之極性。舉例而言，可在每個晶圓曝光之間(例如在約100個個別晶粒曝光之後)發生切換，或在較長時間間隔時(例如在每10個或50個晶圓曝光之後)發生切換。此切換降低了電極周圍及之間的絕緣將在延長使用期間崩潰之可能性。施加至電極之電壓之極性的此切換可被稱作再極化。極化狀態中之每一者可被稱作夾具之激勵狀態。舉例而言，在第一激勵狀態中，可向電極104A施加正電壓，且在第二激勵狀態中，可向電極104A施加負電壓。替代地，夾具之激勵狀態通常可被稱作夾具之組態。夾具組態可包括激勵狀態，且視情況包括另外組態細節(例如組件是否由器件夾持)。 During use, the polarity of the voltage applied to electrodes 104A to 104D is regularly switched. For example, switching may occur between each wafer exposure (e.g., after approximately 100 individual die exposures), or at longer intervals (e.g., after every 10 or 50 wafer exposures) switch. This switch reduces the likelihood that the insulation around and between the electrodes will collapse during extended use. This switching of the polarity of the voltage applied to the electrodes may be referred to as repolarization. Each of the polarization states may be referred to as an excitation state of the fixture. For example, in a first excitation state, a positive voltage may be applied to electrode 104A, and in a second excitation state, a negative voltage may be applied to electrode 104A. Alternatively, the energized state of the clamp may generally be referred to as the configuration of the clamp. The clamp configuration may include activation states and, optionally, additional configuration details (eg, whether the component is clamped by the device).
未由圖案化器件MA對次級電極114A至114D進行掩蔽之結果為：可在次級夾具電極之相鄰且相反極化之電極之間(例如，電極114A至114B之間)或在次級電極與其他附近組件之間建立外部電場。舉例而言，可在次級電極114A至114D與圖案化器件MA之任一側上之導電塗層126、128之間或在次級電極114A至114D與遮蔽葉片140、142、144、146之間建立電場。此場線在圖2b及圖2c中示意性地展示。 The result of not masking secondary electrodes 114A-114D by patterned device MA may be between adjacent and oppositely polarized electrodes of the secondary clamp electrode (eg, between electrodes 114A-114B) or between secondary electrodes 114A-114B. An external electric field is established between the electrode and other nearby components. For example, there may be between secondary electrodes 114A-114D and conductive coatings 126, 128 on either side of patterned device MA or between secondary electrodes 114A-114D and shadow blades 140, 142, 144, 146. establish an electric field. This field line is shown schematically in Figures 2b and 2c.
當然，應理解，在夾具100之正常操作期間，將在夾具100之表面與圖案化器件MA之表面之間建立電場。此外，歸因於各個帶電表面(包括微影設備內之其他組件，諸如(例如)遮蔽葉片140、142、144、146)之間的緊密分離，可發生靜電放電。亦即，可在任何帶電表面之間發生靜電放電，而具有放電隨著電場強度增大而增大的可能性。靜電放電可自表面產生粒子，且亦可釋放先前附接至微影設備內之表面之粒子。應理 解，此粒子釋放在微影設備中係非所要的，此係由於粒子可降落於該設備之決定性區上，從而有可能導致經處理基板中之圖案化缺陷。 Of course, it should be understood that during normal operation of clamp 100, an electric field will be established between the surface of clamp 100 and the surface of patterned device MA. Additionally, electrostatic discharges can occur due to the close separation between various charged surfaces, including other components within the lithography apparatus such as, for example, masking blades 140, 142, 144, 146. That is, electrostatic discharge can occur between any charged surfaces, with the potential for the discharge to increase as the electric field strength increases. Electrostatic discharge can generate particles from surfaces and can also release particles previously attached to surfaces within the lithography equipment. It should be reasonable It is understood that the release of such particles in lithography equipment is undesirable because the particles can land on critical areas of the equipment, potentially causing patterning defects in the processed substrate.
此外，已在運用Cr塗佈之測試圖案化器件執行之測試中觀測到已知與靜電放電損壞相關聯的利希滕貝格(Lichtenberg)圖案。相似地，亦在此等測試中已觀測到具有指示經由高能製程(例如已熔融且再凝固之奈米球)產生之形態的Cr粒子。因此，應理解，靜電放電可產生非想要的粒子。 Additionally, the Lichtenberg pattern, known to be associated with electrostatic discharge damage, has been observed in tests performed using Cr-coated test patterned devices. Similarly, Cr particles with morphologies indicative of production via high-energy processes, such as nanospheres that have been melted and re-solidified, have also been observed in these tests. Therefore, it is understood that electrostatic discharge can produce undesirable particles.
當然，應理解，減小夾具電壓可導致靜電場減小，且因此導致由於靜電放電而在圖案化器件上存在之缺陷的減小。已在圖案化器件具有含Mo之正面塗層之系統中觀測到此減小。亦即，夾具電壓之減小已被證實為顯著地減小倍縮光罩上之Mo粒子產生之缺陷之數目。然而，夾具電壓之此減小在此可導致夾持力減小之一些情況下可並非實用的。 Of course, it should be understood that reducing the clamp voltage can result in a reduction in the electrostatic field and, therefore, in the presence of defects on the patterned device due to electrostatic discharge. This reduction has been observed in systems where patterned devices have front-side coatings containing Mo. That is, a reduction in the clamp voltage has been shown to significantly reduce the number of defects generated by Mo particles on the reticle. However, this reduction in clamp voltage may not be practical in some situations where it may result in a reduction in clamping force.
在一些情況下，有可能改良夾具電極周圍之屏蔽，以便減小在倍縮光罩上觀測到之缺陷之數目。此屏蔽可顯著地減少Mo及Cr缺陷。然而應瞭解，在正常使用中並不屏蔽圖2b、圖2c中所展示之突起部108及110。 In some cases, it may be possible to improve the shielding around the fixture electrodes in order to reduce the number of defects observed on the reticle. This shield can significantly reduce Mo and Cr defects. However, it should be understood that the protrusions 108 and 110 shown in Figures 2b and 2c are not shielded during normal use.
靜電放電對於表膜而言亦可為有問題的。超薄表膜薄膜可用以防止粒子在微影設備之各個區之間移動。然而，應理解，超薄表膜薄膜(其可例如含有厚度為大約幾奈米之金屬層)在任何顯著電流流動通過金屬層的情況下可能過度加熱及斷裂。當然應理解，靜電放電可導致顯著電流流動通過此薄膜。因而，靜電放電亦對表膜帶來風險。 Electrostatic discharge can also be problematic for surface films. Ultra-thin pellicle films are used to prevent particles from moving between areas of the lithography equipment. However, it should be understood that ultrathin pellicle films (which may, for example, contain a metal layer on the order of a few nanometers thick) may overheat and break if any significant current flows through the metal layer. It will of course be understood that electrostatic discharge can cause significant current to flow through this film. Therefore, electrostatic discharge also poses risks to the surface film.
另外，如上文所提及，靜電夾具規則地再極化。每一再極化將導致任何未屏蔽之電極周圍的電場之正負號改變。若帶電粒子在第一 極化狀態(例如，施加負電壓)期間被吸引至彼電極，則一旦極化狀態已改變，其可被排斥。此外，夾具表面上之粒子在夾具處於第一極化狀態時(例如在將負電壓施加至電極時)可變得帶電。然而，一旦極化狀態已改變，則此類帶電粒子可被排斥。亦即，強靜電力可克服吸引力且致使釋放任何經截留粒子，此有可能導致更多粒子入射於圖案化器件或其他系統組件上。 Additionally, as mentioned above, electrostatic clamps repolarize regularly. Each repolarization will cause the sign of the electric field around any unshielded electrode to change. If the charged particle is in the first It is attracted to that electrode during a polarization state (eg, application of a negative voltage) and can be repelled once the polarization state has changed. Additionally, particles on the surface of the clamp may become charged when the clamp is in a first polarization state (eg, when a negative voltage is applied to the electrode). However, once the polarization state has changed, such charged particles can be repelled. That is, strong electrostatic forces can overcome the attractive force and cause any trapped particles to be released, potentially causing more particles to be incident on the patterned device or other system components.
更詳細地說，由靜電夾具產生之高電場強烈地吸引任何自由電荷。自由電荷意謂並不結合至實體基板而是根據電場線自由移動的電荷(正電荷-例如離子，或負電荷-例如電子)。此外，在EUV曝光期間產生充足的自由電荷。舉例而言，可由光發射產生電子且亦自EUV誘發之電漿產生電子，該EUV誘發之電漿通常在存在氫氣(其常常存在於微影工具中)的情況下產生。亦可在EUV電漿內產生正離子。因此，在微影曝光期間，未屏蔽之夾具耳狀物108、110很可能吸引自由電荷，從而導致任何自由空間電場崩潰(亦即由自由電荷補償)，且意謂電場被限制至夾具之內部部件(亦即夾具電極與現在帶電之夾具表面之間)。夾具表面處之所得高電荷密度將很可能將電荷轉移至任何經截留粒子，其中該等粒子接著被靜電場更強地吸引。 In more detail, the high electric field generated by the electrostatic clamp strongly attracts any free charges. Free charges mean charges (positive charges - such as ions, or negative charges - such as electrons) that are not bound to the physical substrate but are free to move according to electric field lines. Additionally, sufficient free charge is generated during EUV exposure. For example, electrons may be generated from light emission and also from EUV-induced plasma, which is typically generated in the presence of hydrogen gas, which is often present in lithography tools. Positive ions can also be generated in EUV plasma. Therefore, during lithographic exposure, the unshielded clamp ears 108, 110 are likely to attract free charges, causing any free space electric field to collapse (i.e., compensated by the free charges), and meaning that the electric field is confined to the interior of the clamp component (i.e. between the clamp electrode and the now charged clamp surface). The resulting high charge density at the surface of the clamp will likely transfer charge to any trapped particles, which are then more strongly attracted to the electrostatic field.
接著，當夾具極性反轉(其中不再存在EUV電漿)時，經截留帶電粒子現在將具有與電極相等正負號之電荷，此將產生遠離表面之強排斥電力。 Then, when the clamp polarity is reversed (there is no longer EUV plasma in it), the trapped charged particles will now have a charge of the same sign as the electrode, which will create a strong repulsive electric force away from the surface.
舉例而言，可估計次級電極中之每一者(亦即電極114A至114D中之每一者)將具有大約10pF至約500pF(例如約100pF)之電容。可基於每一電極之(已知)面積、夾具介電質之(已知)電容率及(已知)介電 層厚度來演算電極電容。 For example, it can be estimated that each of the secondary electrodes (ie, each of electrodes 114A through 114D) will have a capacitance of about 10 pF to about 500 pF (eg, about 100 pF). can be based on the (known) area of each electrode, the (known) permittivity of the fixture dielectric, and the (known) dielectric layer thickness to calculate electrode capacitance.
假定使用為2kV之夾持電壓，則每一耳狀物上之電荷為200nC(Q=CV)，其對應於約720μC/m2之表面電荷密度。此電荷密度將產生約4.107V/m之場強度E(根據E=σ/2ε 0，且假定場在兩個方向上輻射，從而導致場強度除以因數二)。 Assuming a clamping voltage of 2 kV is used, the charge on each ear is 200 nC (Q=CV), which corresponds to a surface charge density of approximately 720 μC/ m2 . This charge density will produce a field strength E of approximately 4.10 7 V/m (according to E =σ/2 ε 0 and assuming that the field radiates in both directions, resulting in a field strength divided by a factor of two).
現在將更詳細地論述電漿產生製程。應理解，光束B內之EUV光子將電離氫分子，從而產生H2 +離子及自由電子。在使用13.5nm EUV輻射之實例中，每一光子可具有約92eV之能量，其中分子氫之電離能量約為15eV。因此，所產生之自由電子可具有足夠能量(例如>75eV)及範圍以相對遠離初始電離事件產生次級電漿。另外，以此方式釋放之電子(亦即具有約75eV之能量)可電離另外一個、兩個或甚至三個氫分子。因此，即使在EUV光子入射的情況下僅產生初級電漿(其通常不包括夾具耳狀物108、110)，亦可在夾具耳狀物108、110附近產生次級電漿。如上文所描述，遮蔽葉片140至146與圖案化器件MA間隔開約5mm至10mm。因此，到達夾具耳狀物108、110之任何電漿應擴散通過形成於葉片140至146與圖案化器件MA之間的隙縫，或在原位產生為次級電漿。 The plasma generation process will now be discussed in more detail. It should be understood that EUV photons in beam B will ionize hydrogen molecules, thereby producing H 2 + ions and free electrons. In an example using 13.5 nm EUV radiation, each photon may have an energy of about 92 eV, with the ionization energy of molecular hydrogen being about 15 eV. Therefore, the free electrons generated may have sufficient energy (eg, >75 eV) and range to generate a secondary plasma relatively far from the initial ionization event. Additionally, the electrons released in this manner (ie, having an energy of approximately 75 eV) can ionize one, two, or even three additional hydrogen molecules. Therefore, even if only a primary plasma is generated upon EUV photon incidence (which typically does not include the clamp ears 108, 110), a secondary plasma can be generated in the vicinity of the clamp ears 108, 110. As described above, the masking blades 140 to 146 are spaced apart from the patterned device MA by approximately 5 mm to 10 mm. Therefore, any plasma reaching the clamp ears 108, 110 should either diffuse through the gap formed between the blades 140-146 and the patterned device MA, or be generated in situ as a secondary plasma.
圖3展示在EUV曝光期間在圖案化器件附近的經模型化電漿密度。水平軸展示距圖案化器件MA之中心之距離R(以cm為單位)，而豎直軸展示距夾具表面之距離z(以cm為單位)。此模型假定EUV源具有40W之輸出功率及5Pa之氫壓。在經模型化環境中，圖案化器件MA被展示為阻擋輻射路徑，其中遮蔽葉片140、142敞開約10mm以使EUV輻射能夠到達圖案化器件MA之中心部分。 Figure 3 shows modeled plasma density near a patterned device during EUV exposure. The horizontal axis shows the distance R (in cm) from the center of the patterned device MA, while the vertical axis shows the distance z (in cm) from the fixture surface. This model assumes that the EUV source has an output power of 40W and a hydrogen pressure of 5Pa. In the modeled environment, the patterned device MA is shown blocking the radiation path, with the shielding blades 140, 142 opening approximately 10 mm to enable EUV radiation to reach the central portion of the patterned device MA.
可看到，鄰近於圖案化器件MA之中心區，電漿密度達到 約108個離子/立方公分。然而，此密度在遮蔽葉片下方(其中EUV光子未直接到達)在距圖案化器件MA之中心約1.5cm處減小至約107個離子/立方公分，且距圖案化器件MA之中心約4cm處減小至約106個離子/立方公分。 It can be seen that near the central area of the patterned device MA, the plasma density reaches about 10 8 ions/cubic centimeter. However, this density decreases to about 10 7 ions/cm3 below the shielding blade (where the EUV photons do not directly reach it) at about 1.5 cm from the center of the patterned device MA and about 4 cm from the center of the patterned device MA is reduced to approximately 10 6 ions/cubic centimeter.
在上述演算之後且在假定約100nm之粒子直徑在密度為106個離子/立方公分至107個離子/立方公分之電漿環境中已接收約10至100個電荷的情況下，在夾具再極化之後帶電表面粒子上之所得排斥靜電力(在不存在電漿的情況下)將約為10-8N至10-7N。吸引力範德瓦耳斯(Van de Waal)及其他黏著力可被預期約為10-9N至10-8N。 After the above calculation and assuming that a particle diameter of about 100 nm has received about 10 to 100 charges in a plasma environment with a density of 10 6 ions/cubic centimeter to 10 7 ions/cubic centimeter, the fixture is then The resulting repulsive electrostatic force on the charged surface particles after polarization (in the absence of plasma) will be approximately 10 -8 N to 10 -7 N. Attractive Van de Waal and other adhesion forces can be expected to be approximately 10 -9 N to 10 -8 N.
因而，根據上文所闡明之假定及近似演算，夾具表面上之經截留粒子因此可經歷強排斥力，其通常將能夠克服較弱黏著力。以此方式釋放之任何粒子將沿著電場線加速，且可降落於遮蔽葉片140至146、圖案化器件MA或其他系統組件上。 Thus, based on the assumptions and approximations stated above, trapped particles on the surface of the clamp can therefore experience strong repulsive forces, which will generally be able to overcome weaker adhesion forces. Any particles released in this manner will be accelerated along the electric field lines and may land on the shielding blades 140-146, patterned devices MA, or other system components.
另外，歸因於氫電漿產生而在EUV曝光開始之後不久之自由電荷密度的顯著及突然增大(如圖3中所說明)及環繞夾具100及經夾持圖案化器件MA之介質之電導率的對應增大可導致高暫態電流在系統組件之間流動。 Additionally, there is a significant and sudden increase in free charge density shortly after the start of the EUV exposure due to hydrogen plasma generation (as illustrated in Figure 3) and the conductance of the medium surrounding the clamp 100 and clamped patterned device MA. The corresponding increase in rate can result in high transient currents flowing between system components.
應理解，在夾持期間，可在夾具介電質內及在夾具表面與經夾持圖案化器件或其他系統組件(該等其他系統組件可遠離夾具表面幾公分)之間建立電場。然而，歸因於氫電漿產生而在環繞夾具之區中之電導率的突然增大可導致延伸超出夾具表面(例如在夾具與圖案化器件或其他系統組件之間)的任何所建立電場崩潰，此係由於導電電漿將無法支援電場。此可導致夾具介電質內之電場強度快速增大，且可能超過場發射之 臨限值。此外，一旦發生場發射，高電流就可引起夾具電極加熱。此加熱可致使場發射之臨限值減小，從而引起電流增大。此繼而可引起電極進一步加熱，且場發射之臨限值仍進一步減小。因此，以此方式，在EUV曝光開始之後不久之自由電荷密度的突然增大可導致高暫態電流在系統組件之間流動。 It will be appreciated that during clamping, an electric field may be established within the clamp dielectric and between the clamp surface and the clamped patterned device or other system components (which may be several centimeters away from the clamp surface). However, a sudden increase in conductivity in the region surrounding the fixture due to hydrogen plasma generation can cause the collapse of any established electric field that extends beyond the fixture surface (e.g., between the fixture and the patterned device or other system components) , this is because the conductive plasma will not be able to support the electric field. This can cause the electric field strength within the fixture dielectric to increase rapidly and may exceed the field emission Threshold value. Furthermore, once field emission occurs, high currents can cause the clamp electrodes to heat up. This heating can cause the field emission threshold to decrease, causing an increase in current. This in turn can cause further heating of the electrode, and the field emission threshold is still further reduced. Thus, in this manner, a sudden increase in free charge density shortly after the start of EUV exposure can cause high transient currents to flow between system components.
在一些情況下，此類突然電導率改變可在存在此類高場的情況下優先造成自經夾持圖案化器件MA之尖銳特徵之場發射。舉例而言，應理解，塗層128可具有曲率半徑約為例如100nm之尖銳邊緣。相似地，可自夾具之表面發生場發射。 In some cases, such sudden conductivity changes may preferentially cause field emissions from sharp features of the clamped patterned device MA in the presence of such high fields. For example, it is understood that coating 128 may have sharp edges with a radius of curvature of approximately 100 nm, for example. Similarly, field emission can occur from the surface of the fixture.
另外，應理解，橫越夾具電極之平面表面在厚度上大體上均一的介電塗層之厚度可在電極之邊緣處減小。因此，電極邊緣處之電場強度可增大，從而增加在此區域中進行場發射之風險。 Additionally, it will be appreciated that the thickness of the dielectric coating, which is substantially uniform in thickness across the planar surface of the clamp electrode, may decrease at the edges of the electrode. Therefore, the electric field strength at the electrode edge can increase, thereby increasing the risk of field emission in this region.
特定組件或特徵易受場發射影響之程度可取決於材料及/或表面之性質。此外，靜電放電對表面造成損壞之程度亦將取決於材料屬性。舉例而言，可用作圖案化器件之塗層的相對不良導電塗層(例如硬化金屬，諸如CrN、TaN)可容易由於靜電放電而損壞。 The degree to which a particular component or feature is susceptible to field emission may depend on the properties of the material and/or surface. In addition, the extent of surface damage caused by electrostatic discharge will also depend on the material properties. For example, relatively poorly conductive coatings (eg, hardened metals such as CrN, TaN) that can be used as coatings for patterned devices can be easily damaged by electrostatic discharge.
現在參看圖4，現在更詳細地描述圖1及圖2a至圖2c中所說明之微影設備之操作模式。圖4a說明在圖案化器件處所接收之EUV劑量。詳言之，以豎直軸示意性地展示EUV劑量之量值，且以水平軸展示時間。 Referring now to Figure 4, the modes of operation of the lithography apparatus illustrated in Figures 1 and 2a-2c are now described in greater detail. Figure 4a illustrates EUV dose received at a patterned device. In detail, the magnitude of EUV dose is schematically shown on the vertical axis, and time is shown on the horizontal axis.
如上文所提及，規則地反轉施加至靜電夾具100之電極104A至104D之電壓以便保留電絕緣之完整性。施加至彼等電極中之一者之電壓在圖4b中示意性地展示，該圖以豎直軸展示電壓且以水平軸展示時 間。詳言之，電壓自時間t0時之0升高至時間t1時之夾持電壓+VC。電壓接著維持處於+VC歷時曝光循環直至時間t2，在時間t2之後，電壓在時間t3時斜降至0，且接著在時間t4時斜降至-VC。在此時間t4之後，電壓在另一曝光循環期間維持處於-VC。在時間t5時，電壓接著在時間t6時增大至0。此後，夾具電極之此正及負激勵循環繼續，其中穩定的激勵時段提供於每一再極化事件之間。 As mentioned above, the voltage applied to the electrodes 104A-104D of the electrostatic clamp 100 is regularly reversed in order to preserve the integrity of the electrical insulation. The voltage applied to one of the electrodes is schematically shown in Figure 4b, which shows voltage on the vertical axis and time on the horizontal axis. Specifically, the voltage increases from 0 at time t 0 to the clamping voltage +V C at time t 1 . The voltage is then maintained at + VC for the duration of the exposure cycle until time t2 , after which the voltage ramps down to 0 at time t3 , and then ramps down to -VC at time t4 . After this time t4 , the voltage remains at -VC during another exposure cycle. At time t5 , the voltage then increases to 0 at time t6 . Thereafter, this cycle of positive and negative excitation of the clamp electrode continues, with a stable excitation period provided between each repolarization event.
在夾持之穩定時段期間執行微影曝光。然而，應理解，可在所說明電極之正或負極化期間發生曝光。此外，應理解，不同電極將遵循不同激勵循環。舉例而言，對於針對電極104A所說明之每一正至負轉變，電極104B可遵循反向轉變。此外，其他電極可在不同時間再極化(以便確保始終存在施加至圖案化器件MA之一些夾持力)。 Lithographic exposure is performed during the stabilization period of the clamp. However, it should be understood that exposure may occur during positive or negative polarization of the electrodes illustrated. Furthermore, it should be understood that different electrodes will follow different excitation cycles. For example, for each positive to negative transition illustrated for electrode 104A, electrode 104B may follow the reverse transition. Additionally, the other electrodes can be repolarized at different times (so as to ensure that there is always some clamping force applied to the patterned device MA).
再次參看圖4a，在時段TA、TB、TC及TD期間，EUV光束主要用於成像。應注意，時間段TA、TB、TC及TD中之每一者對應於期間夾具極化不改變的一時段。然而，緊接在時段TA之前，存在期間EUV能量入射於圖案化器件MA上之時段TA'。相似地，緊接在時間段TA之後，存在期間EUV能量入射於圖案化器件MA上之短時段TA"。時間段TA可被稱作曝光叢發。時間段TA'及TA"可分別被稱作曝光前叢發及曝光後叢發。曝光叢發TA至TD對應於正用於成像(亦即曝光基板)或度量衡(例如對準、鏡面設定等)之EUV光束。因此，到達圖案化器件MA(且被提供至晶圓載物台)之輻射之強度在此時段期間係決定性的。然而，在曝光前叢發TA'及曝光後叢發TA"等期間，EUV功率仍在圖案化器件處被接收，但不用於成像。因此，到達圖案化器件MA(且被提供至晶圓載物台)之輻射之強度較不具有決定性，且可經受變化。 Referring again to Figure 4a, during periods TA , TB , TC and TD , the EUV beam is primarily used for imaging. It should be noted that each of the time periods TA , TB , TC and TD correspond to a period during which the clamp polarization does not change. However, immediately prior to period TA , there is a period TA ' during which EUV energy is incident on patterned device MA. Similarly, immediately following time period TA , there is a short period TA " during which EUV energy is incident on patterned device MA. Time period TA may be referred to as an exposure burst. Time periods TA ' and TA "Can be referred to as pre-exposure clumps and post-exposure clumps respectively. The exposure bursts TA through TD correspond to the EUV beam being used for imaging (ie, exposing the substrate) or metrology (eg, alignment, mirror setting, etc.). Therefore, the intensity of radiation reaching the patterned device MA (and being provided to the wafer stage) is critical during this period. However, during the pre-exposure burst TA ' and the post-exposure burst TA ", etc., EUV power is still received at the patterned device but is not used for imaging. Therefore, the EUV power reaches the patterned device MA (and is provided to the wafer The intensity of radiation from a circular stage is less decisive and can withstand changes.
應注意，在圖4中所展示之實例中，亦在穩定夾持時段內含有曝光前叢發TA'及曝光後叢發TA"兩者(亦即，時段TA'、TA及TA"皆處於t1與t2之間)，在此期間夾具極化不改變。亦即，在夾具再極化事件之間含有整個EUV脈衝。 It should be noted that in the example shown in Figure 4, both the pre-exposure burst TA ' and the post-exposure burst TA " are also included in the stable clamping period (i.e., the periods TA ', TA and T A "are all between t 1 and t 2 ), during which the polarization of the clamp does not change. That is, the entire EUV pulse is contained between clamp repolarization events.
此外，應理解，所說明之照明及極化序列係示意性的，且不包括全部事件。舉例而言，甚至在表觀連續EUV功率之時段期間，亦可存在施加至EUV源之脈衝，且例如在不同晶粒之成像之間或在晶圓調換期間可存在可選中斷。 Furthermore, it should be understood that the illustrated illumination and polarization sequences are illustrative and do not include all events. For example, there may be pulses applied to the EUV source even during periods of apparent continuous EUV power, and there may be optional interruptions, such as between imaging of different dies or during wafer swaps.
更詳細地說，叢發TA'、TA及TA"中之每一者可包括許多單獨的EUV脈衝，且亦可包括不提供脈衝之時段。舉例而言，曝光叢發TA可對應於全晶圓曝光(例如包含約100個晶粒曝光)，在此期間可存在總計約106個脈衝(例如每晶粒曝光104個脈衝)。在每一晶粒曝光之間，可存在期間並不存在EUV光束之晶圓定位時段。此時段可持續約30ms至40ms。另外，在成像開始之前，可執行各種度量衡動作，在此期間光束B入射於圖案化器件MA上且經提供至基板台WT，但並不入射於基板自身上(基板台WT可移動使得基板W並不處於光束路徑中)。 In more detail, each of bursts TA ', TA , and TA " may include a number of individual EUV pulses, and may also include periods during which no pulses are provided. For example, exposure burst TA may Corresponding to a full wafer exposure (e.g., containing about 100 die exposures), there may be a total of about 10 6 pulses during this period (e.g., 10 4 pulses per die exposure). Between each die exposure, there may be There is no wafer positioning period for the EUV beam during this period. This period can last about 30ms to 40ms. Additionally, various metrological actions can be performed before imaging begins, during which beam B is incident on the patterned device MA and is provided to the substrate table WT, but not incident on the substrate itself (the substrate table WT can be moved so that the substrate W is not in the beam path).
在曝光前叢發TA'及曝光後叢發TA"期間，可監視及控制源SO內之暫態效應(例如以確保在曝光叢發TA期間由晶圓經歷之輻射強度儘可能地均一)。另外，曝光前叢發TA'及曝光後叢發TA"可用以執行校準、對準或度量衡操作，而非晶圓曝光。然而，不論其使用及對基板之影響如何，叢發TA'、TA及TA"各自涉及入射於圖案化器件MA上之EUV輻射。 During the pre-exposure burst TA ' and the post-exposure burst TA ", transient effects within the source SO can be monitored and controlled (e.g. to ensure that the radiation intensity experienced by the wafer during the exposure burst TA is as high as possible Uniform). Additionally, pre-exposure burst TA ' and post-exposure burst TA ' can be used to perform calibration, alignment, or metrology operations other than wafer exposure. However, regardless of their use and impact on the substrate, bursts TA ', TA and TA " each involve EUV radiation incident on the patterned device MA.
應理解，隨著EUV功率在時間t1之後不久快速增大(亦即一旦圖案化器件已被適當夾持)以開始曝光前叢發TA'，靜電夾具周圍環境之 電導率將自非導電環境(包含低密度氫)快速改變至高電導率環境(包含EUV誘發之氫電漿)。如上文所提及，此快速電導率改變可導致靜電放電。此外，在夾具再極化事件期間，截留於夾具突起部108、110上之粒子(其在叢發TA'、TA及TA"期間在電漿環境中可能已變得帶電)可由於電場之突然改變而自夾具表面噴射。 It should be understood that as the EUV power increases rapidly shortly after time t 1 (i.e. once the patterned device has been properly clamped) to initiate the pre-exposure burst TA ', the conductivity of the environment surrounding the electrostatic clamp will change from non-conductive The environment (containing low-density hydrogen) rapidly changes to a high-conductivity environment (containing EUV-induced hydrogen plasma). As mentioned above, this rapid conductivity change can lead to electrostatic discharge. Additionally, during the clamp repolarization event, particles trapped on the clamp protrusions 108, 110, which may have become charged in the plasma environment during the bursts TA ' , TA , and TA ", may due to A sudden change in the electric field causes an ejection from the surface of the fixture.
圖5說明根據本發明之一實施例之經修改照明序列。圖5b說明大體上對應於以上參看圖4b所描述之靜電夾具之極化序列的靜電夾具之極化序列。然而，圖5a展示與以上參看圖4a所描述之照明序列相比經修改的照明序列。 Figure 5 illustrates a modified illumination sequence according to one embodiment of the invention. Figure 5b illustrates a polarization sequence for an electrostatic clamp that generally corresponds to the polarization sequence of the electrostatic clamp described above with reference to Figure 4b. However, Figure 5a shows a modified illumination sequence compared to the illumination sequence described above with reference to Figure 4a.
詳言之，在曝光前時段TA'期間，EUV功率逐漸斜升，而非EUV功率突然自關斷狀態切換至接通狀態。亦即，入射於圖案化器件MA上之EUV功率在夾具已經極化(或再極化)時逐漸增加。相似地，在曝光後時段TA"期間，EUV功率可逐漸斜降，而非EUV功率突然自接通狀態切換至關斷狀態。應注意，在曝光前時段TA'及曝光後時段TA"期間，EUV功率經施加至圖案化器件但並不用於成像。在本發明之涵義內，此可被稱作圖案化器件之非成像曝光。此非成像曝光因此係指在此期間EUV輻射光束入射於圖案化器件上且在此期間無輻射投影至基板上之曝光；該非成像曝光可例如在該複數次成像曝光之連續成像曝光之間予以執行。 In detail, during the pre-exposure period TA ', the EUV power gradually ramps up, while the non-EUV power suddenly switches from the off state to the on state. That is, the EUV power incident on the patterned device MA gradually increases as the fixture has been polarized (or repolarized). Similarly, during the post-exposure period TA ", the EUV power can gradually ramp down, while the non-EUV power suddenly switches from the on state to the off state. It should be noted that during the pre-exposure period TA ' and the post-exposure period TA "During this time, EUV power is applied to the patterned device but is not used for imaging. Within the meaning of the present invention, this may be referred to as non-imagewise exposure of the patterned device. The non-imaging exposure thus refers to an exposure during which the EUV radiation beam is incident on the patterned device and during which no radiation is projected onto the substrate; the non-imaging exposure may, for example, be given between successive imaging exposures of the plurality of imaging exposures implement.
在本發明之實施例中，在夾具之極化或再極化期間應用此非成像曝光。 In embodiments of the present invention, this non-imaging exposure is applied during polarization or repolarization of the fixture.
例如在非成像曝光期間施加之EUV功率之軟性斜升導致圖案化器件MA及靜電夾具100周圍之區之電導率的逐漸增加。介質電導率之此逐漸增加並不致使靜電場以突然方式崩潰，而是允許電荷根據預先存 在之場線朝向各個表面洩漏。此製程允許補償已由於先前夾具極化狀態而變得帶電之任何表面。相似地，可將要補償夾具或圖案化器件之表面上之任何帶電粒子。 For example, a soft ramp in EUV power applied during non-imaging exposure results in a gradual increase in the conductivity of the patterned device MA and the area surrounding the electrostatic clamp 100 . This gradual increase in the conductivity of the medium does not cause the electrostatic field to collapse in a sudden manner, but rather allows the charge to change according to the pre-existing The field lines leak toward all surfaces. This process allows compensation of any surfaces that have become charged due to previous fixture polarization states. Similarly, any charged particles on the surface of the fixture or patterned device may be compensated.
軟性斜坡可被預期遍及多個EUV脈衝延伸。舉例而言，軟性斜升可花費不到一千個脈衝，或不到約20毫秒。較佳地，軟性斜升可花費不到10,000個脈衝，或不到約200毫秒。一般而言，與晶圓之曝光時間相比，斜坡時段將較小。晶圓曝光可例如持續約30秒。與約30秒之晶圓曝光相比，不到約1秒(或約50,000個脈衝)之斜坡時段可被認為係軟性斜坡，或逐漸增加。 A soft ramp can be expected to extend across multiple EUV pulses. For example, a soft ramp can take less than a thousand pulses, or less than about 20 milliseconds. Preferably, the soft ramp may take less than 10,000 pulses, or less than about 200 milliseconds. Generally speaking, the ramp period will be small compared to the exposure time of the wafer. Wafer exposure may last, for example, about 30 seconds. A ramp period of less than about 1 second (or about 50,000 pulses) may be considered a soft ramp, or a gradual increase, compared to a wafer exposure of about 30 seconds.
諸如以上所描述之軟性斜升的軟性斜升可在以下情形中之一或多者中有益：a.在EUV設備之第一次起動之後；b.在裝載新圖案化器件MA之後；及c.在靜電夾具電極之極性反轉(再極化)之後。 A soft ramp, such as the one described above, may be beneficial in one or more of the following situations: a. After the first start-up of the EUV apparatus; b. After loading a new patterned device MA; and c .After the polarity of the electrostatic clamp electrode is reversed (repolarized).
可以若干不同方式執行此軟性斜升。舉例而言，可藉由逐漸斜升源之脈衝能量來進行斜升。替代地或另外，軟性斜升可藉由緩慢地增加一起貢獻於遞送至晶圓之總輻射能量(或劑量)的複數個小型叢發中之每一者中的脈衝數目來實施。每一小型叢發可例如包含約10個脈衝，其各自具有約100ns之持續時間且在約50kHz之頻率下經遞送。在使用LPP輻射源之狀況下，可藉由控制所應用雷射之操作來控制所產生之EUV脈衝之數目。在此LPP輻射源中，藉由運用一或多個雷射光束輻照諸如錫(Sn)目標之燃料目標來產生EUV脈衝。可例如藉由控制輻照之燃料目標之數目來控制所產生之EUV輻射之量。可例如控制如所應用之脈衝式雷射光束僅輻 照兩個燃料目標中之一者或三個燃料目標中之一者，因此將EUV輻射之量減少至50%或33%。替代地或另外，可藉由***及緩慢收縮遮蔽葉片140、142、144、146中之一或多者來實施軟性斜升。當然，亦可實施替代機構以用於EUV能量之此軟性斜升。 This soft ramp can be performed in several different ways. For example, ramping can be performed by gradually ramping up the pulse energy of the source. Alternatively or additionally, soft ramping may be implemented by slowly increasing the number of pulses in each of a plurality of small bursts that together contribute to the total radiation energy (or dose) delivered to the wafer. Each mini-burst may, for example, comprise about 10 pulses, each having a duration of about 100 ns and delivered at a frequency of about 50 kHz. In the case of an LPP radiation source, the number of EUV pulses generated can be controlled by controlling the operation of the applied laser. In this LPP radiation source, EUV pulses are generated by irradiating a fuel target, such as a tin (Sn) target, with one or more laser beams. The amount of EUV radiation produced can be controlled, for example, by controlling the number of fuel targets irradiated. It is possible, for example, to control the applied pulsed laser beam to only radiate Illuminating one of two fuel targets or one of three fuel targets, thereby reducing the amount of EUV radiation to 50% or 33%. Alternatively or additionally, a soft ramp may be implemented by inserting and slowly retracting one or more of the shielding blades 140, 142, 144, 146. Of course, alternative mechanisms may be implemented for this soft ramping of EUV energy.
軟性斜坡可例如以小跳躍(例如至全成像功率之約5%至10%)開始，之後在成像曝光開始時自此位準逐漸增加至100%成像功率。替代地，輻射功率可自0%線性增大至100%。在輻射功率之逐漸增加期間，可存在若干小的步階，其導致大體上線性之總體增大。舉例而言，功率可在步階中增大，例如10%中之5%。此增大仍將導致夾具及圖案化器件周圍之介質之電導率的逐漸改變。 The soft ramp may, for example, start with a small jump (eg to about 5% to 10% of full imaging power) and then gradually increase from this level to 100% imaging power at the beginning of the imaging exposure. Alternatively, the radiated power can increase linearly from 0% to 100%. During the gradual increase in radiated power, there may be several small steps leading to a generally linear overall increase. For example, the power can be increased in steps, such as 5% of 10%. This increase will still result in a gradual change in the conductivity of the medium surrounding the fixture and patterned device.
一般而言，應理解，提供電導率之逐漸改變會降低與電導率之突然增大相關聯的放電風險。 In general, it is understood that providing a gradual change in conductivity reduces the risk of discharge associated with a sudden increase in conductivity.
在一些狀況下，EUV能量可以與圖4a中所說明相似(亦即對稱)之方式斜降。然而，在其他實施例中，EUV能量可突然停止，如在目前先進技術中係慣例的。 In some cases, the EUV energy can ramp down in a similar (i.e., symmetrical) manner to that illustrated in Figure 4a. However, in other embodiments, the EUV energy may be stopped abruptly, as is common practice in currently advanced technology.
如圖5中所說明，可在EUV斜升或斜降期間發生夾具電極再極化。替代地，可在EUV關斷時段期間發生夾具電極再極化。亦可指出，EUV可在電壓降低期間接通，亦即經施加電壓降低為零，如例如在物件卸載之前進行。如圖5b中所展示之時段t11至t12可表示此電壓降低。如所提及，在該時段期間施加至少低位準之輻射亦可為有利的。 As illustrated in Figure 5, clamp electrode repolarization can occur during EUV ramp-up or ramp-down. Alternatively, clamp electrode repolarization may occur during the EUV turn-off period. It may also be noted that the EUV can be switched on during a voltage reduction, ie the applied voltage is reduced to zero, as for example before the object is unloaded. The period t 11 to t 12 as shown in Figure 5b may represent this voltage decrease. As mentioned, it may also be advantageous to apply at least a low level of radiation during this period.
圖6展示其中相對於作為慣例之EUV功率激勵而修改EUV功率激勵的另一實施例。圖6b說明夾具極化序列，其相似於以上參看圖4b所描述之夾具極化序列。然而，在圖6a中，可看到，在EUV曝光脈衝T 中之每一者之間，存在圖案化器件MA之恆定EUV照明。亦即，甚至在靜電夾具經再極化之時段期間，亦將EUV輻射提供至圖案化器件MA。此要求在多個曝光脈衝之間的時段期間，維持由源SO輸出之EUV能量，且控制遮蔽葉片140至146以便允許EUV輻射中之至少一些到達圖案化器件MA。如上文所提及，在本發明之涵義內，將EUV功率施加至圖案化器件而不將該功率用於成像被稱作非成像曝光。此非成像曝光可導致產生EUV誘發之電漿。 Figure 6 shows another embodiment in which EUV power stimulation is modified relative to EUV power stimulation as is customary. Figure 6b illustrates a clamp polarization sequence similar to that described above with reference to Figure 4b. However, in Figure 6a, it can be seen that during the EUV exposure pulse T Between each of these, there is constant EUV illumination of the patterned device MA. That is, EUV radiation is provided to the patterned device MA even during the period during which the electrostatic clamp is repolarized. This requires maintaining the EUV energy output by the source SO during the period between multiple exposure pulses, and controlling the shadow blades 140-146 to allow at least some of the EUV radiation to reach the patterned device MA. As mentioned above, applying EUV power to a patterned device without using the power for imaging is referred to as non-imaging exposure within the meaning of the present invention. This non-imaging exposure can result in the generation of EUV-induced plasma.
藉由在再極化期間(亦即在自夾具之第一激勵狀態至第二激勵狀態之轉變期間)將EUV照明提供至圖案化器件MA，應理解，相對導電介質(亦即EUV誘發之氫電漿)將始終被提供於經夾持圖案化器件MA及靜電夾具100附近。因而，在夾具100再極化時，由EUV誘發之氫電漿(如圖3中所展示，其將存在於夾具突起部108、110周圍)提供之自由空間電荷將允許電荷快速地再分佈。大量自由電荷將有效地掩蔽由次級電極114A至114D產生之場，且降低由表面釋放粒子之可能性。自由電荷亦將用以減少危險高強度場。此將導致經由EUV誘發之電漿減少介電質表面與圖案化器件塗層之邊緣之場集中特徵之間的高暫態電流。亦即，藉由始終提供導電介質，可降低或完全消除高暫態電流及在每一曝光脈衝開始時與EUV能量之突然開始相關聯的放電風險。亦可指出，EUV可在電壓降低期間接通，亦即經施加電壓降低為零，如例如在物件卸載之前進行。如圖6b中所展示之時段t11至t12可表示此電壓降低。如所提及，在該時段期間施加至少低位準之輻射亦可為有利的。 By providing EUV illumination to the patterned device MA during repolarization (i.e., during the transition from the first excitation state to the second excitation state of the fixture), it will be understood that the relatively conductive medium (i.e., EUV-induced hydrogen Plasma) will always be provided in the vicinity of the clamped patterned device MA and the electrostatic clamp 100. Thus, upon repolarization of the clamp 100, the free space charge provided by the EUV-induced hydrogen plasma (which will be present around the clamp protrusions 108, 110 as shown in Figure 3) will allow the charge to be rapidly redistributed. The large amount of free charge will effectively mask the field generated by secondary electrodes 114A-114D and reduce the possibility of particle release from the surface. Free charges will also be used to reduce dangerous high-intensity fields. This results in high transient currents via EUV-induced plasma reduction between the dielectric surface and the field-concentrating features at the edges of the patterned device coating. That is, by always providing a conductive medium, the risk of high transient currents and discharges associated with the sudden onset of EUV energy at the beginning of each exposure pulse can be reduced or completely eliminated. It may also be noted that the EUV can be switched on during a voltage reduction, ie the applied voltage is reduced to zero, as for example before the object is unloaded. The period t 11 to t 12 as shown in Figure 6b may represent this voltage decrease. As mentioned, it may also be advantageous to apply at least a low level of radiation during this period.
如圖7中所展示，在又一操作模式中，在再極化(圖7b)期間調變EUV功率(圖7a)使得在每一曝光叢發T脈衝之前，存在逐漸斜升RU，在每一曝 光脈衝之後，存在逐漸斜降RD，且在每一EUV叢發T之間，存在施加至倍縮光罩之低EUV功率L。亦即，EUV功率在再極化期間逐漸減小且經維持處於低位準，而非在多個曝光脈衝之間完全移除EUV功率。與以上關於圖6所描述之配置相比，此配置減小了EUV源上之負載，且亦提供如下優點：靜電夾具周圍之介質始終維持處於導電狀態，以便最小化在突然EUV接通期間可觀測到的高暫態電流之效應，且允許在每一再極化事件期間發生電荷補償。亦可指出，EUV可在電壓降低期間接通，亦即經施加電壓降低為零，如例如在物件卸載之前進行。如圖7b中所展示之時段t11至t12可表示此電壓降低。如所提及，在該時段期間施加至少低位準之輻射亦可為有利的。 As shown in Figure 7, in yet another mode of operation, the EUV power (Figure 7a) is modulated during repolarization (Figure 7b) such that before each exposure burst T pulse there is a gradual ramp RU, After an exposure pulse, there is a gradual ramp down RD, and between each EUV burst T, there is a low EUV power L applied to the reticle. That is, EUV power is gradually reduced and maintained at a low level during repolarization, rather than being completely removed between exposure pulses. This configuration reduces the load on the EUV source compared to the configuration described above with respect to Figure 6, and also provides the advantage that the medium surrounding the electrostatic fixture remains conductive at all times, thereby minimizing possible damage during sudden EUV turn-on. The effect of high transient currents is observed and allows charge compensation to occur during each repolarization event. It may also be noted that the EUV can be switched on during a voltage reduction, ie the applied voltage is reduced to zero, as for example before the object is unloaded. The period t 11 to t 12 as shown in Figure 7b may represent this voltage decrease. As mentioned, it may also be advantageous to apply at least a low level of radiation during this period.
應理解，在以上參看圖5、圖6及圖7所描述之配置中之每一者中，可藉由減少由靜電放電事件引起的缺陷及帶電粒子之發射而不改變硬體中之任一者，來改良微影設備之效能。詳言之，以新穎方式使用EUV照明系統之現有特徵，以便減小在再極化事件期間及之後所看到的高自由空間場。 It should be understood that in each of the configurations described above with reference to Figures 5, 6, and 7, the defects and the emission of charged particles caused by electrostatic discharge events can be reduced without changing any of the hardware. Or, to improve the performance of lithography equipment. Specifically, existing features of EUV illumination systems are used in novel ways to reduce the high free space fields seen during and after repolarization events.
在上文所描述實施例中之每一者中，應理解，需要產生EUV誘發之電漿，其在圖案化器件MA附近且尤其在夾具突起部108、110附近提供自由電荷源。然而，亦應理解，為了有效地掩蔽電極114A至114D周圍之場，將需要足夠的自由電荷密度。當然，在任何特定部位處所產生之電荷之密度將取決於任何系統之特定特性，包括EUV強度、氣體密度及系統幾何形狀。此外，所需之自由電荷之量亦將取決於管理參數(例如場強度、電極幾何形狀)。 In each of the embodiments described above, it should be understood that there is a need to generate an EUV-induced plasma that provides a source of free charge near the patterned device MA and particularly near the clamp protrusions 108, 110. However, it should also be understood that in order to effectively shield the field around electrodes 114A-114D, sufficient free charge density will be required. Of course, the density of charge generated at any particular location will depend on the specific characteristics of any system, including EUV intensity, gas density, and system geometry. Furthermore, the amount of free charge required will also depend on the governing parameters (eg field strength, electrode geometry).
在考慮預期將在與夾具次級電極114A至114D相鄰之介電 質表面處累積的電荷之數量的情況下(如上文更詳細地論述)，應理解，必須以至少最小速率供應電荷以便恰當地防止在再極化事件期間建立外部場。 Taking into account the expected dielectric In the case of the amount of charge accumulated at the surface of the mass (as discussed in more detail above), it is understood that the charge must be supplied at at least a minimum rate in order to properly prevent the establishment of external fields during repolarization events.
舉例而言，夾具再極化可被預期在約200ms內或約104個EUV脈衝中發生。此外，夾具再極化轉換速率可例如約為16kV/s。在此速率下，夾具電壓將針對每一EUV脈衝以為或約為0.3V之速率改變。另外，如上文所論述，掩蔽夾持電壓為2kV的夾具耳狀物所需之電荷之數目可為大約1012(200nC
在假定初級電漿離子及次級遠端電漿離子(由在電離期間移除之電子引起)兩者貢獻於存在於夾具耳狀物(如圖3中所展示)處之電荷且遮蔽葉片140至146全開(從而允許全圖案化器件待曝光至輻射光束B)的情況下，咸信104個EUV脈衝將提供足夠的自由電荷以大體上防止在再極化事件期間建立外部場。在此情形下在假定存在40W源功率的情況下，可預期在夾具耳狀物處約為107/cm3之離子密度。 It is assumed that both primary plasma ions and secondary distal plasma ions (caused by electrons removed during ionization) contribute to the charge present at the clamp ears (as shown in Figure 3) and obscure the blade 140 With 146 fully on (thereby allowing a fully patterned device to be exposed to radiation beam B), it is believed that 10 4 EUV pulses will provide sufficient free charge to substantially prevent the establishment of external fields during repolarization events. In this case an ion density of approximately 10 7 /cm 3 at the clamp ears can be expected assuming a 40 W source power.
然而，若自由電荷之通量減小，則可需要較大數目個EUV脈衝以提供足夠的再平衡電荷。舉例而言，若初級電漿不能夠擴散至夾具耳狀物部位，從而導致僅次級電漿貢獻於夾具耳狀物部位處之自由電荷，則可預期在夾具耳狀物處約為106/cm3之離子密度。此離子密度可能未提供足夠的自由電荷來完全補償再極化場。 However, if the flux of free charge is reduced, a larger number of EUV pulses may be required to provide sufficient rebalancing charge. For example, if the primary plasma is not able to diffuse to the clamp ears, resulting in only the secondary plasma contributing to the free charge at the clamp ears, one would expect about 10 6 at the clamp ears /cm 3 ion density. This ion density may not provide enough free charge to fully compensate for the repolarization field.
若判定為此狀況，則有可能減小再極化發生之速率。舉例而言，若再極化速率減小為原先的五分之一(至3.2kV/s)，則夾具再極化將持續約5×104個EUV脈衝，從而提供自由電荷之顯著增大供應以補償改變場。當然應理解，此調整可能造成生產率降低。然而，夾具切換速度減 小為原先的五分之一(如上文所論述)將被預期造成總體生產率減小<0.5%。 If this is determined to be the case, it is possible to reduce the rate at which repolarization occurs. For example, if the repolarization rate is reduced to one-fifth of the original rate (to 3.2 kV/s), the fixture repolarization will last approximately 5×10 4 EUV pulses, thus providing a significant increase in free charge Supplied to compensate for changing fields. It should of course be understood that this adjustment may result in reduced productivity. However, reducing the fixture changeover speed by one fifth (as discussed above) would be expected to result in a <0.5% reduction in overall productivity.
當然，熟習此項技術者應理解，所需之自由電荷之數量將取決於夾持電壓及幾何形狀，且所產生之可提供掩蔽效應的自由電荷之比例亦將取決於許多因素(其中一些在上文加以論述)。然而，熟習此項技術者將能夠根據需要修改各種參數(例如EUV強度、EUV脈衝持續時間、EUV脈衝數目、H2氣壓、夾具電壓、切換速率、遮蔽葉片位置等)以確保恰當地掩蔽夾具耳狀物。舉例而言，可執行經驗研究以建立在特定配置中所需及/或提供之自由電荷之位準。替代地，可進行電荷密度模型化以便判定在夾具耳狀物部位處將經歷何位準之電荷密度。 Of course, those skilled in the art will understand that the amount of free charge required will depend on the clamping voltage and geometry, and the proportion of free charge produced that will provide a masking effect will also depend on a number of factors (some of which are discussed above). However, those skilled in the art will be able to modify various parameters (e.g. EUV intensity, EUV pulse duration, number of EUV pulses, H gas pressure, clamp voltage, switching rate, masking blade position, etc.) as needed to ensure proper masking of the clamp ears. shape object. For example, empirical studies may be performed to establish the levels of free charge required and/or provided in a particular configuration. Alternatively, charge density modeling can be performed to determine what level of charge density will be experienced at the clip ear sites.
在參看圖6至圖8所描述之實施例中，EUV誘發之電漿係由圖案化器件之所謂的非成像曝光產生，亦即，在此期間輻射光束入射於圖案化器件上且在此期間無輻射投影至基板上之曝光；該非成像曝光係在該複數次成像曝光之連續成像曝光之間予以執行。 In the embodiments described with reference to Figures 6-8, the EUV-induced plasma is generated by so-called non-imaging exposure of the patterned device, that is, during which a radiation beam is incident on the patterned device and during which An exposure without radiation projection onto a substrate; the non-imaging exposure is performed between successive imaging exposures of the plurality of imaging exposures.
藉由在非成像曝光期間將輻射光束提供於圖案化器件處，有可能藉助於電漿提供自由電荷源，該電漿將藉由存在於圖案化器件周圍之氣體分子(例如氫)之電離而產生。將既在由輻射光束直接照明之區中又在相鄰區中(例如歸因於擴散，及次級電子)產生電漿。以此方式，單一輻射光束(例如EUV輻射光束)可既用於成像目的，又在靜電夾具之再極化期間提供自由電荷源。 By providing a radiation beam at the patterned device during non-imaging exposure, it is possible to provide a source of free charge by means of a plasma that will be generated by ionization of gas molecules (such as hydrogen) present around the patterned device. produce. Plasma will be generated both in the area directly illuminated by the radiation beam and in adjacent areas (eg due to diffusion, and secondary electrons). In this way, a single radiation beam, such as an EUV radiation beam, can be used both for imaging purposes and to provide a source of free charge during repolarization of the electrostatic clamp.
在一替代實施例中，可藉由使EUV功率照射於圖案化器件附近之表面上而將EUV功率應用為自由電荷源。因而，用於與靜電夾具相鄰地產生自由電荷之替代方式為將輻射光束提供於不同於圖案化器件之表 面處，例如遮光片或遮蔽葉片之表面。如上文所提及，遮光片或遮蔽葉片配置可用以阻擋輻射光束到達圖案化器件或用以控制入射於圖案化器件上之輻射光束之空間延伸。歸因於輻射光束與存在於或提供於遮光片或光罩葉片配置周圍、遮光片或光罩葉片配置處或附近的氣體分子(例如氫)之相互作用，輻射光束或其一部分之施加至該(該等)遮光片或光罩葉片上亦可導致產生自由電荷。將既在由輻射光束直接照明之區中又在相鄰區中(例如歸因於擴散，及次級電子)產生自由電荷。由於遮光片或光罩葉片配置通常比較接近於圖案化器件且因此比較接近於靜電夾具，故藉由輻照遮光片或光罩葉片配置所產生之自由電荷亦可導致與靜電夾具相鄰之自由電荷。藉由輻照遮光片或光罩葉片配置而產生自由電荷因此亦可被認為係用於產生與靜電夾具相鄰之自由電荷之機構。 In an alternative embodiment, EUV power can be applied as a source of free charge by shining the EUV power on a surface adjacent to the patterned device. Thus, an alternative for generating free charges adjacent to the electrostatic fixture is to provide the radiation beam on a surface other than the patterned device. surface, such as the surface of a shading sheet or a shading blade. As mentioned above, a shield or shield blade configuration may be used to block the radiation beam from reaching the patterned device or to control the spatial extension of the radiation beam incident on the patterned device. The application of the radiation beam, or a portion thereof, to the radiation beam, or a portion thereof, is due to the interaction of the radiation beam with gas molecules (e.g., hydrogen) present or provided around, at or near the mask or mask blade arrangement. Free charges may also be generated on (these) light shields or mask blades. Free charges will be generated both in the area directly illuminated by the radiation beam and in adjacent areas (eg due to diffusion, and secondary electrons). Since the mask or mask blade configuration is typically closer to the patterned device and therefore closer to the electrostatic fixture, the free charges generated by irradiating the mask or mask blade configuration can also result in free charge adjacent to the electrostatic fixture. charge. The generation of free charges by irradiating a mask or mask blade arrangement may therefore also be considered a mechanism for generating free charges adjacent to an electrostatic fixture.
在一些實施例中，可提供次級電離源，藉此允許由除EUV源SO之外之構件在靜電夾具附近產生電漿。此配置可降低EUV源SO之總體輸出負載。應理解，上文所描述之實施例可藉由要求與成像所需之EUV輸出相比額外的EUV輸出而對EUV源SO提出額外要求。另外，在一些實施例中，EUV源沒有可能連續產生功率(如圖6a中所說明)。相似地，EUV源沒有可能及/或不期望提供在標稱輸出功率之範圍0%至100%內的任意EUV脈衝能量，同時亦確保清潔的收集器操作及脈衝能量穩定性。 In some embodiments, a secondary ionization source may be provided, thereby allowing plasma to be generated near the electrostatic fixture by means other than the EUV source SO. This configuration reduces the overall output load of the EUV source SO. It should be understood that the embodiments described above may place additional demands on the EUV source SO by requiring additional EUV output compared to that required for imaging. Additionally, in some embodiments, it is not possible for the EUV source to continuously generate power (as illustrated in Figure 6a). Similarly, it is not possible and/or undesirable for an EUV source to provide arbitrary EUV pulse energy within the range of 0% to 100% of the nominal output power while ensuring clean collector operation and pulse energy stability.
因而，在一些實施例中，可較佳提供用於相較於初級EUV源產生增加之氣體電導率的區之替代機構。 Thus, in some embodiments, it may be preferable to provide an alternative mechanism for generating a region of increased gas conductivity compared to the primary EUV source.
舉例而言，源可與靜電夾具100及經夾持圖案化器件MA接近地提供。該源可較佳被置放於夾具突起部108、110附近。可使用複數個源。舉例而言，源可為能夠在清潔環境中在低於1巴之壓力下操作的軟x 射線源或VUV光源。源可包含具有約0.1W至1W之功率的低功率電離器。一個此類合適器件可為如由Hamamatsu Photonics K.K.(日本，Shizuoka，Hamamatsu市)製造之VUV電離器L12542。在一些實施例中，源可包含放射性源或電子束源。 For example, the source may be provided in close proximity to the electrostatic clamp 100 and the clamped patterned device MA. This source may preferably be placed near the clamp protrusions 108, 110. Multiple sources can be used. For example, the source may be a soft x that can operate at pressures below 1 bar in a clean environment. Ray source or VUV light source. The source may include a low power ionizer with a power of approximately 0.1W to 1W. One such suitable device may be, for example, the VUV ionizer L12542 manufactured by Hamamatsu Photonics K.K. (Hamamatsu, Shizuoka, Japan). In some embodiments, the source may include a radioactive source or an electron beam source.
如圖8a至圖8c(其中子圖及所說明部件大體上對應於圖2a至圖2c中所展示之子圖及部件)中所展示，源S與靜電夾具100及圖案化器件MA相鄰地提供。在一實施例中，可例如在靜電夾具100之再極化期間激勵源S，藉此確保夾具100及圖案化器件MA附近之氫氣經電離以產生氫電漿。如上文所論述，在再極化期間提供自由電荷有效地掩蔽了由靜電夾具100(尤其在次級電極114A至114D周圍)產生之場。 As shown in Figures 8a-8c (wherein the sub-figures and illustrated components generally correspond to those shown in Figures 2a-2c), source S is provided adjacent to electrostatic clamp 100 and patterned device MA . In one embodiment, the source S may be excited, for example, during repolarization of the electrostatic clamp 100, thereby ensuring that hydrogen gas near the clamp 100 and the patterned device MA is ionized to generate hydrogen plasma. As discussed above, providing free charge during repolarization effectively masks the field generated by the electrostatic clamp 100, particularly around the secondary electrodes 114A-114D.
舉例而言，如圖8a至圖8c(其展示源S發射VUV輻射之時間)所說明，由於發射之VUV輻射而產生電漿P。電漿P使得貫穿夾具及圖案化器件環境提供自由電荷雲。因而，當可存在建立於電極104A至104D中之每一者與經夾持圖案化器件MA之相鄰區之間的電場時，未經掩蔽電極114A至114D自電漿吸引電荷雲，藉此形成掩蔽電荷QA、QB、QC及QD。掩蔽電荷QA至QD中之每一者具有與對應的次級電極114A至114D之正負號相反的正負號。因此，在靜電夾具100周圍並未建立顯著及非想要的電場，從而降低了圖2b及圖2c中所說明之場F1、F2及F3之效應。 For example, a plasma P is generated as a result of the emitted VUV radiation, as illustrated in Figures 8a to 8c (which show the time at which source S emits VUV radiation). Plasma P provides a free charge cloud throughout the fixture and patterned device environment. Thus, while there may be an electric field established between each of electrodes 104A-104D and adjacent regions of clamped patterned device MA, unshielded electrodes 114A-114D attract a charge cloud from the plasma, thereby Masking charges QA, QB, QC and QD are formed. Each of the masking charges QA through QD has a sign opposite to that of the corresponding secondary electrode 114A through 114D. Therefore, no significant and undesirable electric fields are established around the electrostatic clamp 100, thereby reducing the effects of the fields F1, F2 and F3 illustrated in Figures 2b and 2c.
因此可使用源S來代替由源SO產生之EUV輻射，以提供自由空間電荷來掩蔽非想要的電場，從而有效地使自由空間場崩潰(藉由提供可補償任何自由空間場之移動電荷)。此掩蔽導致由夾具100產生之電場大體上被約束至環繞靜電夾具電極114A至114D之絕緣體之內部。 Source S can therefore be used instead of the EUV radiation produced by source SO to provide free space charges to mask the undesired electric fields, thereby effectively collapsing the free space fields (by providing mobile charges that compensate for any free space fields) . This shielding causes the electric field generated by clamp 100 to be substantially confined to the interior of the insulator surrounding electrostatic clamp electrodes 114A-114D.
應瞭解，次級電離源S可特別提供於夾具100之突起部 108、110附近，以便向最需要其之區提供局域化自由電荷。因而，應理解，次級源S可用以提供對以上參看圖6及圖7所描述之照明方案的替代方案，在該等照明方案中，由源SO產生之EUV能量在再極化期間經提供至圖案化器件。 It should be understood that the secondary ionization source S can be specially provided on the protruding portion of the clamp 100 Near 108 and 110, in order to provide localized free charge to the areas that need it most. Thus, it should be understood that the secondary source S may be used to provide an alternative to the illumination schemes described above with reference to Figures 6 and 7 in which EUV energy generated by the source SO is provided during repolarization. to patterned devices.
一般而言，EUV源SO及源S(其可例如包含軟x射線源或VUV電離器)可各自被認為係電離輻射源之實例。另外，與氫(或其他)氣體源結合之此類源可被認為係用於產生自由電荷之機構。亦即，含有正離子及自由電子兩者之氫電漿可被認為係自由電荷雲。另外，此類自由電荷包含正自由電荷及負自由電荷兩者。此允許自由電荷補償及掩蔽兩個極性之場。應理解，在每一夾具極化狀態中之不同電極處，及在不同極化狀態期間之電極中之每一者處經歷兩個極性之場。 In general, EUV source SO and source S (which may include, for example, a soft x-ray source or a VUV ionizer) may each be considered to be examples of ionizing radiation sources. Additionally, such a source combined with a source of hydrogen (or other) gas may be considered a mechanism for generating free charges. That is, a hydrogen plasma containing both positive ions and free electrons can be considered a free charge cloud. In addition, such free charges include both positive free charges and negative free charges. This allows the free charges to compensate and mask the fields of both polarities. It will be appreciated that fields of two polarities are experienced at different electrodes in each clamp polarization state, and at each of the electrodes during different polarization states.
此外，如上文簡要描述，可在自夾具100移除圖案化器件MA後即在夾具100與圖案化器件MA之間建立顯著電壓。現在參看圖9更詳細地描述圖案化器件MA移除製程。 Additionally, as briefly described above, a significant voltage may be established between the clamp 100 and the patterned device MA upon removal of the patterned device MA from the clamp 100 . The patterned device MA removal process is now described in greater detail with reference to FIG. 9 .
圖9a展示其中圖案化器件MA夾持至其之夾具100。該經夾持圖案化器件MA被展示為與交換總成150間隔開。該交換總成包含支撐支撐結構154之交換器件152。支撐結構154包含自支撐結構154之表面朝向圖案化器件MA延伸的小數目個突起部156。突起部156可具有例如約200μm之高度。交換總成150經組態以使圖案化器件MA朝向及遠離夾具100移動，例如以使能夠用替代圖案化器件交換圖案化器件MA或能夠清潔圖案化器件MA。交換器件152可包含相對於微影設備之其餘部分移動以便將圖案化器件MA至及自裝載鎖(圖中未繪示)移動的機器人臂。支撐結構154及尤其突起部156在輸送期間支撐圖案化器件MA。自圖9a可見， 突起部156與圖案化器件MA之總面積相比具有小面積。因而，當圖案化器件MA由支撐結構154支撐時，僅存在小接觸面積。在圖9a所展示之組態中，在靜電夾具100與圖案化器件MA之間存在小間隙g。舉例而言，此間隙g可約為10μm(其對應於提供於靜電件100之表面上之瘤節106的高度)。 Figure 9a shows the clamp 100 with the patterned device MA clamped thereto. The clamped patterned device MA is shown spaced apart from the switch assembly 150 . The switch assembly includes switch devices 152 supporting a support structure 154 . The support structure 154 includes a small number of protrusions 156 extending from the surface of the support structure 154 toward the patterned device MA. The protrusion 156 may have a height of about 200 μm, for example. The exchange assembly 150 is configured to move the patterned device MA toward and away from the fixture 100 , for example, to enable the patterned device MA to be exchanged for a replacement patterned device or to enable cleaning of the patterned device MA. Exchange device 152 may include a robotic arm that moves relative to the rest of the lithography apparatus to move patterned devices MA to and from a load lock (not shown). The support structure 154 and particularly the protrusions 156 support the patterned device MA during transport. As can be seen from Figure 9a, The protrusion 156 has a small area compared to the total area of the patterned device MA. Thus, when patterned device MA is supported by support structure 154, there is only a small contact area. In the configuration shown in Figure 9a, there is a small gap g between the electrostatic clamp 100 and the patterned device MA. For example, the gap g may be approximately 10 μm (which corresponds to the height of the knobs 106 provided on the surface of the electrostatic element 100 ).
圖案化器件MA之表面被展示為以間隙b與支撐結構154之表面間隔開。在圖9a所展示之組態中，間隙b超過200μm(突起部156之高度)。因而，當圖案化器件MA與突起部156之頂部表面間隔開時，在圖案化器件MA之平面表面與支撐結構154之平面表面之間必須存在至少200μm之間隙。 The surface of patterned device MA is shown spaced apart from the surface of support structure 154 by a gap b. In the configuration shown in Figure 9a, the gap b exceeds 200 μm (the height of the protrusion 156). Thus, when the patterned device MA is spaced apart from the top surface of the protrusion 156, there must be a gap of at least 200 μm between the planar surface of the patterned device MA and the planar surface of the support structure 154.
相反地，在圖9b(其包括與圖9a中所展示相同的組件)中所展示之組態中，圖案化器件MA被展示為位於突起部156之頂部上。因此，間隙b為200μm，且間隙g(亦即，靜電夾具100與圖案化器件MA之間的間隙)大於10μm，此意謂在瘤節106(或實際上夾具100之任何部件)與圖案化器件MA之間不存在實體接觸。 In contrast, in the configuration shown in Figure 9b (which includes the same components as shown in Figure 9a), the patterned device MA is shown on top of the protrusion 156. Therefore, gap b is 200 μm, and gap g (i.e., the gap between electrostatic clamp 100 and patterned device MA) is greater than 10 μm, which means that between knob 106 (or indeed any component of clamp 100) and the patterned device MA There is no physical contact between devices MA.
圖10展示說明經由移除圖案化器件MA而使間隙b及g之改變的時間序列。在時間t20時，間隙g最初為10μm(其對應於瘤節106之高度，此意謂在瘤節106之頂部與圖案化器件MA之表面之間存在接觸)。時間t20時之間隙b遠超過約900μm，且因此在交換總成150之任何部分與圖案化器件MA之間不存在接觸。 Figure 10 shows a time sequence illustrating changes in gaps b and g by removing patterned device MA. At time t20, the gap g is initially 10 μm (which corresponds to the height of the knob 106, meaning that there is contact between the top of the knob 106 and the surface of the patterned device MA). The gap b at time t20 is well over about 900 μm, and therefore there is no contact between any part of the switch assembly 150 and the patterned device MA.
在時間t21時，交換總成150接近圖案化器件MA，如由距離b之減小可看出。此移動在時間t22時停止，此時交換總成150經組態以懸停於圖案化器件MA下方，從而維持約900μm之間隙b(亦即，突起部 156之200μm高度加700μm之間隙)。接著在時間t23時，靜電夾具100及經夾持圖案化器件MA朝向交換器件150逐漸降低。此移動緩慢繼續直至約t24，此時距離b已減小至約200μm。亦即，靜電夾具100及經夾持圖案化器件MA降低直至圖案化器件MA之下表面(如圖8a及圖8b中所展示)與突起部156之上表面接觸。此組態保持直至約時間t25。在此時間段期間，供應至夾具電極104A至104D、114A至114D之電壓被移除，使得靜電夾具100不再夾持圖案化器件MA。 At time t21, switch assembly 150 approaches patterned device MA, as can be seen by the decrease in distance b. This movement ceases at time t22, when the switch assembly 150 is configured to hover below the patterned device MA, maintaining a gap b of approximately 900 μm (i.e., the protrusions 156 of 200μm height plus 700μm gap). Then at time t23, the electrostatic clamp 100 and the clamped patterned device MA gradually lower toward the switching device 150. This movement continues slowly until about t24, when the distance b has reduced to about 200 μm. That is, the electrostatic clamp 100 and the clamped patterned device MA are lowered until the lower surface of the patterned device MA (as shown in FIGS. 8 a and 8 b ) contacts the upper surface of the protrusion 156 . This configuration remains until approximately time t25. During this time period, the voltage supplied to the clamp electrodes 104A-104D, 114A-114D is removed so that the electrostatic clamp 100 no longer clamps the patterned device MA.
在時間t25時，靜電夾具向上移動以移動遠離圖案化器件MA(其現在完全由交換總成150之突起部156支撐)，從而導致間隙g增大。此移動繼續直至約時間t26，此時間隙g已增大至約700μm。此時，交換總成150支撐圖案化器件MA且懸停於靜電夾具100下方。在時間t27時，致使交換總成150使所支撐圖案化器件MA遠離靜電夾具100移動，使得間隙g自700μm增大至更大距離。此移動繼續直至時間t28(之後交換總成150可移動至圖案化器件交換區域，諸如裝載鎖)。 At time t25, the electrostatic clamp moves upward to move away from the patterned device MA (which is now fully supported by the protrusion 156 of the switch assembly 150), causing the gap g to increase. This movement continues until approximately time t26, at which time the gap g has increased to approximately 700 μm. At this time, the switching assembly 150 supports the patterned device MA and hovers below the electrostatic clamp 100 . At time t27, the switching assembly 150 is caused to move the supported patterned device MA away from the electrostatic clamp 100, so that the gap g increases from 700 μm to a larger distance. This movement continues until time t28 (after which the exchange assembly 150 may move to a patterned device exchange area, such as a load lock).
應理解，電容存在於上文所描述之系統組件中之若干系統組件之間。如圖11中所展示，系統可經模型化為串聯配置之多個電容。詳言之，交換設備150與圖案化器件MA之下表面(在圖9a、圖9b中所展示之定向中)之間的電容可被認為係可變電容Cb，其依據間隙b而變化。電容Cb可被演算如下：
圖案化器件MA自身之電容可被認為係固定電容Cr，其可被演算如下：
圖案化器件MA之頂側與靜電夾具100之間的間隙可被認為係可變電容Cg，其可被演算如下：
最後，夾具電容Cd提供於夾具100之電極(其平均起來具有為0V之電壓)與靜電夾具之表面之間。此電容Cd係固定的，且可被演算如下：
當然，應理解，上述表達式表示實際電容之簡化，且忽略了各種寄生及額外組件。另外，假定低壓氫氣環境之電容率相似於自由空間之電容率(ε 0)。相似地，假定每一電容之面積等於A，而忽略了瘤節106及突起部156之效應。然而，所描述模型用以說明電容及電荷分佈之一般趨勢。熟習此項技術者應理解，可在需要時執行更準確模型化。 Of course, it should be understood that the above expression represents a simplification of the actual capacitance and ignores various parasitics and additional components. In addition, it is assumed that the permittivity of the low-pressure hydrogen environment is similar to the permittivity of free space ( ε 0 ). Similarly, it is assumed that the area of each capacitor is equal to A, and the effects of knobs 106 and protrusions 156 are ignored. However, the model described is intended to illustrate general trends in capacitance and charge distribution. Those skilled in the art will understand that more accurate modeling can be performed when desired.
如圖11中所說明，電容Cd、Cg、Cr及Cb串聯地配置。此外，電容Cd及Cr係固定的，而電容Cg及Cb係可變的。因此，應理解，在無電荷能夠進入或離開系統的封閉系統中且針對給定初始充電狀態，夾具 100與圖案化器件MA之間的分離度g及圖案化器件MA與交換設備150之間的分離度b的任何變化將會導致可變電容Cg及Cb改變。此外，此電容改變亦將導致橫越各個電容之電壓根據分離度之改變可能顯著地改變。 As illustrated in Figure 11, capacitors Cd , Cg , Cr , and Cb are configured in series. In addition, the capacitances C d and C r are fixed, while the capacitances C g and C b are variable. Therefore, it should be understood that in a closed system where no charge can enter or leave the system and for a given initial charge state, the separation g between the clamp 100 and the patterned device MA and the patterned device MA and the switching device 150 Any change in separation b will cause the variable capacitances C g and C b to change. In addition, this capacitance change will also cause the voltage across each capacitance to change significantly depending on the change in separation.
詳言之，針對每一電容必須始終維持關係Q=CV(假定無電荷被注入)。因此，若電容C發生改變且彼電容中所含有之電荷Q之量維持相同，則電壓V必須與改變之電容C成反比地改變。此可導致顯著電壓放大。 Specifically, the relationship Q=CV must always be maintained for each capacitor (assuming no charge is injected). Therefore, if the capacitance C changes and the amount of charge Q contained in that capacitance remains the same, the voltage V must change in inverse proportion to the changing capacitance C. This can result in significant voltage amplification.
當然，應瞭解，在一些情況下電荷可經注入至多個電容器之間的各個節點中。詳言之，注入夾具表面處之電荷可經模型化為電荷Qs。注入至圖案化器件之背面中之電荷可經模型化為電荷Qb。注入至圖案化器件之正面中之電荷可經模型化為電荷Qf。電荷源Qs、Qb及Qf展示於圖11中。 Of course, it should be understood that in some cases charge may be injected into various nodes between multiple capacitors. In detail, the charge injected at the surface of the fixture can be modeled as charge Q s . The charge injected into the backside of the patterned device can be modeled as charge Qb . The charge injected into the front side of the patterned device can be modeled as charge Qf . Charge sources Qs , Qb and Qf are shown in Figure 11.
圖12a至圖12c展示在卸載序列期間之夾具環境之模型之各個參數的改變。詳言之，圖12a展示在自夾具100移除圖案化器件MA時在與以上參看圖10所描述之移動相似的一系列移動期間之分離度b及g的改變。x軸展示以秒為單位之時間，而y軸展示以公尺為單位之(在對數尺度上)距離。首先，距離b在時間3s時自約100mm減小至約1mm，之後距離b在約時間6s時進一步減小至約200μm(亦即突起部156與圖案化器件MA之間的接觸)。接著，距離g在時間8s時自約10μm增大至時間9s時之約700μm，之後再次自約時間11s增大。 Figures 12a to 12c show changes in various parameters of the model of the fixture environment during the unloading sequence. In particular, Figure 12a shows changes in the separations b and g during a series of movements similar to those described above with reference to Figure 10 when removing the patterned device MA from the fixture 100. The x-axis shows time in seconds, while the y-axis shows distance in meters (on a logarithmic scale). First, the distance b decreases from about 100 mm to about 1 mm at about time 3 s, and then the distance b further decreases to about 200 μm at about time 6 s (ie, the contact between the protrusion 156 and the patterned device MA). Then, the distance g increases from about 10 μm at time 8 s to about 700 μm at time 9 s, and then increases again from about time 11 s.
如上文參看圖11所描述，與各種系統組件相關聯之電容亦根據分離度b及g改變。與此等各種移動相關聯之改變之電容展示於圖12b中，其中x軸展示以秒為單位之時間且y軸展示(再次在對數尺度上)電容器 中之每一者之電容Cd、Cg、Cr及Cb。如所預期，可看到電容Cd及Cr橫越時間段並不改變。然而，可看到，電容Cb在時間2秒與時間6秒之間增大了大致三個數量級(其對應於交換總成150朝向圖案化器件MA之移動)。相反地，自時間8秒至時間12秒，電容Cg(其對應於圖案化器件MA與靜電夾具100之間的電容)在兩個階段減小了大致4個數量級。詳言之，電容Cg首先在時間9s時自約20nF減小至約300pf，且接著在時間12s時再次減小至約20pF。 As described above with reference to Figure 11, the capacitance associated with various system components also changes according to the separation b and g. The changing capacitance associated with these various movements is shown in Figure 12b, where the x-axis shows time in seconds and the y-axis shows (again on a logarithmic scale) the capacitance C d , C of each of the capacitors. g , C r and C b . As expected, it can be seen that the capacitances C d and Cr do not change across the time period. However, it can be seen that capacitance C b increases by approximately three orders of magnitude between time 2 seconds and time 6 seconds (which corresponds to the movement of switch assembly 150 toward patterned device MA). On the contrary, from time 8 seconds to time 12 seconds, the capacitance C g (which corresponds to the capacitance between the patterned device MA and the electrostatic clamp 100 ) decreases by approximately 4 orders of magnitude in two stages. In detail, capacitance C g first decreases from about 20 nF to about 300 pf at time 9 s, and then decreases again to about 20 pF at time 12 s.
圖12c展示在上文所論述之移除序列期間在圖11中所展示之等效電路內之各個點處的電壓。詳言之，夾具介電質表面處之電壓Vd(其亦等於橫越電容器Cd之電壓)被展示為在該序列期間僅最小地改變。 Figure 12c shows the voltages at various points within the equivalent circuit shown in Figure 11 during the removal sequence discussed above. In particular, the voltage V d at the fixture dielectric surface (which is also equal to the voltage across capacitor C d ) is shown to change only minimally during the sequence.
圖案化器件MA之正面處之電壓VFS可被理解為電壓Vd、Vg及Vr(其分別為橫越電容器Cd、Cg及Cr之電壓)之和。電壓VFS亦等於橫越電容器Cb之電壓Vb。可看到VFS在時間11秒時自相對較小量升高至約500伏特。此對應於圖案化器件MA與靜電夾具100之間的間隙g顯著升高之時間。 Voltage V FS at the front side of patterned device MA can be understood as the sum of voltages V d , V g and V r (which are the voltages across capacitors C d , C g and Cr respectively). Voltage V FS is also equal to the voltage V b across capacitor C b . V FS can be seen to rise from a relatively small amount to about 500 volts at time 11 seconds. This corresponds to the time when the gap g between the patterned device MA and the electrostatic clamp 100 rises significantly.
然而，到目前為止，電壓之最顯著改變發生於圖案化器件MA之背面處，其係由電壓Vd及Vg之和(亦即橫越電容器Cd及Cg之電壓之和)表示。可看到此電壓在圖案化器件MA與靜電夾具100之間的初始小分離度(亦即在約8秒時達約700μm之分離度)期間增大至高於1000伏特。然而，接著在約時間11秒時電壓更顯著升高至約高於4300伏特，其對應於自圖案化器件MA至靜電夾具100之距離g的顯著增大。 However, by far the most significant change in voltage occurs at the backside of patterned device MA, represented by the sum of voltages Vd and Vg (ie, the sum of the voltages across capacitors Cd and Cg ). This voltage can be seen to increase to over 1000 volts during the initial small separation between the patterned device MA and the electrostatic clamp 100 (ie, a separation of about 700 μm at about 8 seconds). However, the voltage then increases significantly to approximately above 4300 volts at approximately time 11 seconds, which corresponds to a significant increase in the distance g from the patterned device MA to the electrostatic clamp 100 .
應注意，經模型化電壓改變係基於一些電荷將自靜電夾具100注入至圖案化器件MA之背面之假定。此經模型化電荷注入在圖13中 加以說明，該圖13大體上相似於以上參看圖11所描述之等效電路，且包括單一電荷源Q，該單一電荷源經模型化以在約時間約1秒時注入大致500nC電荷。此電荷注入亦可在圖11c之插圖中看到，該圖展示在擴展之豎直尺度上在時間1s與8s之間的電壓。詳言之，可看到，在時間1s時，注入500nC電荷造成電壓VBS、VFS突然增大至約80V。 It should be noted that the modeled voltage changes are based on the assumption that some charge will be injected from the electrostatic clamp 100 to the backside of the patterned device MA. This modeled charge injection is illustrated in Figure 13, which is generally similar to the equivalent circuit described above with reference to Figure 11, and includes a single charge source Q that is modeled to run in about time Approximately 500nC charge is injected at 1 second. This charge injection can also be seen in the inset of Figure 11c, which shows the voltage on an extended vertical scale between times 1 s and 8 s. In detail, it can be seen that at time 1 s, the injection of 500 nC charge causes the voltages V BS and V FS to suddenly increase to about 80V.
實際上，可在夾持期間將電荷累積於圖案化器件MA之背面處，而非在時間1s時精確地注入電荷。又，當圖案化器件被夾持時，可自夾具表面上之尖銳特徵(例如經截留粒子)發生場發射。此可導致圖案化器件變得帶電(常常帶負電)。 In fact, charge can be accumulated at the backside of the patterned device MA during clamping, rather than precisely injecting charge at time 1 s. Also, when the patterned device is clamped, field emission can occur from sharp features (eg, trapped particles) on the surface of the clamp. This can cause the patterned device to become charged (often negatively charged).
假定不將另外電荷引入至系統，圖11及圖13中所說明之等效電路模型可用以回應於以上所描述之電容之改變而模型化電壓之演進。圖12c中所展示之所得高電壓應被理解為顯著增加了歸因於在靜電夾具100及圖案化器件MA附近之氫氣之崩潰(例如歸因於圖案化器件MA表面處之電壓超過氫之最低帕申限制，其約為250V)而造成的放電風險。 Assuming no additional charge is introduced into the system, the equivalent circuit model illustrated in Figures 11 and 13 can be used to model the evolution of voltage in response to the changes in capacitance described above. The resulting high voltage shown in Figure 12c should be understood as a significant increase due to the collapse of hydrogen near the electrostatic clamp 100 and the patterned device MA (eg, due to the voltage at the surface of the patterned device MA exceeding the minimum hydrogen Paschen limit, which is approximately 250V).
因此，與微影設備內之靜電放電相關聯的進一步挑戰係在夾持之後之圖案化器件之卸載期間。如上文所描述，電荷可變得被截留於夾具100之介電質表面處。此外，殘餘電荷一旦其已被釋放就可保持於經夾持圖案化器件MA上。隨著鬆開之圖案化器件MA移動遠離夾具表面，夾具表面與圖案化器件表面之間的增加之分離度可導致電容減小及電壓放大。亦即，在給出封閉系統中之電荷與電壓之間的比例關係(亦即Q=C.V)的情況下，當電容改變(與平行板之間的分離度成反比)時，電容之任何減小將導致電壓之成比例增大。因此，在圖案化器件MA與夾具100分離時，圖案化器件之電壓有可能將足夠升高以致使發生氫氣之電崩潰。此 放電可導致粒子產生，粒子產生可導致後續缺陷。 Therefore, a further challenge associated with electrostatic discharge within lithography equipment is during unloading of patterned devices after clamping. As described above, charges may become trapped at the dielectric surface of clamp 100 . Furthermore, residual charge may remain on the clamped patterned device MA once it has been released. As the released patterned device MA moves away from the clamp surface, the increased separation between the clamp surface and the patterned device surface can result in capacitance reduction and voltage amplification. That is, given the proportional relationship between charge and voltage in a closed system (that is, Q = C.V), when the capacitance changes (inversely proportional to the separation between parallel plates), any decrease in capacitance will result in a proportional increase in voltage. Therefore, when the patterned device MA is separated from the fixture 100, the voltage of the patterned device may rise sufficiently to cause an electrical collapse of the hydrogen gas to occur. this Discharges can lead to particle production, which can lead to subsequent defects.
然而，已認識到，可藉由在卸載製程期間引入自由電荷而在一定程度上減輕變化電容之效應。舉例而言，單獨的電離源S或實際上EUV源SO可用以產生氫電漿，氫電漿提供自由電荷(如上文詳細所描述)且允許在移除製程期間放寬橫越各種介電質組件(及間隙)所建立之場。 However, it has been recognized that the effects of varying capacitance can be mitigated to some extent by introducing free charges during the offloading process. For example, a separate ionization source S or indeed an EUV source SO can be used to generate a hydrogen plasma that provides free charge (as described in detail above) and allows for relaxation across the various dielectric components during the removal process (and gaps) the field established.
提供自由電荷可導致建立於各種系統組件之間的電壓之顯著減小。亦即，由圖12c中所說明之高電壓產生的所建立之電場可藉由引入額外自由電荷來補償。此類電荷可被認為待由如圖11中所說明之電荷源Qs、Qb及Qf提供至圖案化器件及夾具之表面。此等電荷源實際上由氫電漿提供，該氫電漿將足夠電荷提供至夾具100及圖案化器件MA等效電路內之節點中的每一者，以便確保其經維持處於中性狀態。亦即，電漿內之自由電荷在任何電場開始經建立時由該等電場驅動，且致使彼等場崩潰。 Providing free charge can result in a significant reduction in the voltage established between the various system components. That is, the electric field created by the high voltage illustrated in Figure 12c can be compensated by introducing additional free charges. Such charges can be considered to be provided to the surface of the patterned device and fixture by charge sources Qs , Qb , and Qf as illustrated in Figure 11. These charge sources are actually provided by a hydrogen plasma that provides sufficient charge to each of the nodes within the fixture 100 and the patterned device MA equivalent circuit to ensure that they are maintained in a neutral state. That is, the free charges within the plasma are driven by any electric fields as they are initially established, and cause their fields to collapse.
以此方式，可減輕或完全避免與在自靜電夾具10移除後橫越圖案化器件MA建立顯著電壓相關聯的潛在問題。如上文所提及，應理解，此效應並非二元的，且若提供不足電荷，則仍可建立一些(減小之強度)場。然而，應理解，甚至電壓放大之減小(而非完全避免)可為有益的，尤其是在電壓因此始終維持低於(約250V)之氫之最低帕申限制的情況下。 In this manner, potential problems associated with the establishment of significant voltage across the patterned device MA upon removal from the electrostatic clamp 10 may be mitigated or completely avoided. As mentioned above, it is understood that this effect is not binary and if insufficient charge is provided, some (reduced intensity) field may still be established. However, it should be understood that even a reduction (rather than a complete avoidance) of voltage amplification can be beneficial, especially if the voltage is therefore always maintained below the lowest Paschen limit of hydrogen (approximately 250 V).
此外，可在夾具100與圖案化器件MA之分離期間的各個時間提供自由電荷。實際上，應理解，當圖案化器件MA被夾持時，自由電荷可難以在相鄰表面之間穿透。因此，可存在供最佳地提供自由電荷之有效最小分離度。此分離度將取決於所需穿透深度(亦即，自由電荷應在夾具與圖案化器件之分離表面之間穿透以提供有效電荷中和的距離)。 Additionally, free charge may be provided at various times during separation of fixture 100 from patterned device MA. Indeed, it is understood that when the patterned device MA is clamped, free charges may have difficulty penetrating between adjacent surfaces. Therefore, there can be an effective minimum separation for optimal provision of free charges. This degree of separation will depend on the required penetration depth (ie, the distance over which free charges should penetrate between the fixture and the separation surface of the patterned device to provide effective charge neutralization).
最小分離度亦可為電壓之函數(該電壓在分離度增大期間增大，如上文所描述)。舉例而言，在分離表面之間的電壓小(例如為零)的情況下，電荷歸因於隨機擴散及表面複合而將不穿透至小間隙中。然而，在分離表面之間存在顯著電壓的情況下，亦將在夾具100及圖案化器件MA周圍之(中性)環境與夾具100及圖案化器件MA之具有增大之電壓的表面之間產生場。任何此類場可用以致使具有適當正負號之自由電荷被吸入至分離表面之間的體積中。此場之效應通常將更強於自由電荷之隨機擴散，從而導致與不存在場之情形相比，電荷更深地穿透至體積中。對於大約1mm之穿透深度，允許電荷穿透至夾具區域之最小間隙可例如為大約100微米。 The minimum separation can also be a function of voltage (which increases during increasing separation, as described above). For example, where the voltage between the separating surfaces is small (eg, zero), the charge will not penetrate into the small gap due to random diffusion and surface recombination. However, in the presence of significant voltages between the separation surfaces, there will also be generated between the (neutral) environment surrounding the clamp 100 and patterned device MA and the surfaces of the clamp 100 and patterned device MA with increased voltages. field. Any such field can be used to cause free charges of appropriate sign to be drawn into the volume between the separation surfaces. The effect of this field will generally be stronger than the random diffusion of free charges, causing the charges to penetrate deeper into the volume than would be the case in the absence of the field. For a penetration depth of approximately 1 mm, the minimum gap allowing charge penetration to the clamp area may be, for example, approximately 100 microns.
應理解，在圖案化器件MA之實體邊緣(或圖案化器件之削邊)與導電塗層128之開始部分之間可存在某一距離。此距離可約為1mm。因而，小於1mm之電漿穿透深度將僅將自由電荷提供至圖案化器件MA之非導電表面，而不提供至導電塗層128。導電塗層128可充當在放電期間可局部地且在極短時間內被釋放的電荷之儲集器。因而，在分離期間將自由電荷提供至導電塗層128以便中和任何電荷不平衡性係有益的。 It should be understood that there may be some distance between the physical edge of the patterned device MA (or a chamfered edge of the patterned device) and the beginning of the conductive coating 128 . This distance may be approximately 1mm. Thus, a plasma penetration depth of less than 1 mm will provide free charge only to the non-conductive surface of the patterned device MA and not to the conductive coating 128 . Conductive coating 128 may act as a reservoir for charge that may be released locally and within a very short time during discharge. Therefore, it is beneficial to provide free charge to the conductive coating 128 during separation to neutralize any charge imbalance.
亦應理解，在分離組件之間的電壓差超過危險位準(例如250V)之前提供自由電荷可為有益的。因此，可存在供最佳地提供自由電荷之有效最大分離度。應提供電荷之最大分離距離將取決於多個因素而變化。 It will also be appreciated that it may be beneficial to provide free charge before the voltage difference between separate components exceeds a dangerous level (eg, 250V). Therefore, there can be an effective maximum separation for optimal provision of free charges. The maximum separation distance at which charges should be provided will vary depending on a number of factors.
舉例而言，夾具100與圖案化器件MA之平行表面之間的初始分離度為一個此類因素。此初始分離度可為大約10微米(其對應於瘤節106之高度，此意謂在瘤節106之頂部與圖案化器件MA之表面之間存在直 接接觸)。應理解，電容將與夾具100及圖案化器件MA之平行表面的分離度(而非瘤節與圖案化器件MA之間的分離度，其最初為零)成反比地改變。因此，對應於危險的電壓位準之分離度將取決於初始分離位準。亦即，當瘤節接觸圖案化器件時之夾具100與圖案化器件MA之平行表面之間的分離度(例如10微米「分離度」)與當圖案化器件已移動遠離夾具時之夾具100與圖案化器件MA之平行表面之間的分離度之比率將大體上等於彼兩個組態中之電容之比率之倒數。 For example, the initial separation between the parallel surfaces of the fixture 100 and the patterned device MA is one such factor. This initial separation may be approximately 10 microns (which corresponds to the height of the knob 106, meaning there is a direct line between the top of the knob 106 and the surface of the patterned device MA. contact contact). It should be understood that the capacitance will change inversely with the separation between the parallel surfaces of the clamp 100 and the patterned device MA (rather than the separation between the knob and the patterned device MA, which is initially zero). Therefore, the degree of separation corresponding to the hazardous voltage level will depend on the initial separation level. That is, the separation between the parallel surfaces of the clamp 100 and the patterned device MA when the nub contacts the patterned device (e.g., 10 micron "separation") is different from the separation between the clamp 100 and the patterned device MA when the patterned device has moved away from the clamp. The ratio of the separations between the parallel surfaces of the patterned device MA will be substantially equal to the reciprocal of the ratio of the capacitances in those two configurations.
另外，對應於危險的電壓位準之分離度亦將取決於夾具之部件與經夾持圖案化器件之間的電壓不平衡性。舉例而言，應理解，夾持通常由相反電壓經施加至之多個電極來達成。此等電壓有效地相互平衡，從而導致圖案化器件經維持處於為零之標稱總體電壓(即使在將為±1kV至10kV之夾持電壓施加至每一夾具電極時)。然而，亦應理解，可在每電極之確切夾持電壓之間或在每電極之電容方面發生變化。此等因素中之任一者可導致與圖案化器件整體上之電壓中性之偏差。替代地或另外，可例如存在藉由來自存在於夾具之瘤節之間的帶電粒子之微放電進行之電荷轉移。另外，各種替代的電荷轉移機構可導致一旦已自夾具100移除夾持電壓，淨電荷及相關聯電壓就保持於圖案化器件上。 Additionally, the degree of separation corresponding to hazardous voltage levels will also depend on the voltage imbalance between components of the fixture and the clamped patterned device. For example, it will be appreciated that clamping is typically achieved by multiple electrodes to which opposite voltages are applied. These voltages effectively balance each other, causing the patterned device to be maintained at a nominal overall voltage of zero (even when a clamping voltage of ±1 kV to 10 kV is applied to each clamp electrode). However, it is also understood that variations may occur between the exact clamping voltage of each electrode or in the capacitance of each electrode. Any of these factors can cause deviations from voltage neutrality of the patterned device as a whole. Alternatively or additionally, there may be charge transfer by microdischarge from charged particles present between knobs of the clamp, for example. Additionally, various alternative charge transfer mechanisms may result in the net charge and associated voltage remaining on the patterned device once the clamping voltage has been removed from the clamp 100 .
在一實施例中，若假定任何電壓不平衡性小於約~10V(或2kV夾持電壓之~0.5%)且應防止組件之間的電壓超過200V(以最小化放電風險)，則可准許不到20倍之電壓放大。此將要求在分離度(平行表面之間，而非瘤節尖端之間)已增加20倍之前提供補償自由電荷。在其中在夾持期間之標稱分離度為10μm之此類實例中，約200μm之分離度可被認為待最佳地提供自由電荷之有效最大分離度。 In one embodiment, this may be allowed if it is assumed that any voltage imbalance is less than about ~10V (or ~0.5% of the 2kV clamping voltage) and the voltage between components should be prevented from exceeding 200V (to minimize the risk of discharge). to 20 times the voltage amplification. This would require compensating free charges to be provided before the separation (between parallel surfaces, not between nub tips) has increased by a factor of 20. In such examples where the nominal separation during clamping is 10 μm, a separation of approximately 200 μm may be considered to optimally provide an effective maximum separation of free charges.
當然，應理解，提供自由電荷之有效最大及最小分離度將取決於許多特性，且將在不同設備組態及操作條件之間變化。更一般而言，應理解，可在選定之時間產生自由電荷，以便在靜電夾具與先前夾持(及隨後釋放)之組件之間的電位差超過臨限值之前提供電荷以減小(或限制)該電位差。在一實施例中，在分離度已開始增大之前提供自由電荷，直至已經過最小分離度之後的點。在一替代實施例中，在分離度已超過最大分離度之前提供自由電荷，直至已經過最大分離度之後的點。在一替代實施例中，在分離已達到最小分離度之前提供自由電荷，直至已經過最大分離度之後的點。 Of course, it should be understood that the effective maximum and minimum separations provided for free charge will depend on many characteristics and will vary between different device configurations and operating conditions. More generally, it will be understood that free charge can be generated at times selected to provide charge to reduce (or limit) the potential difference between the electrostatic clamp and the previously clamped (and subsequently released) component before it exceeds a threshold value. this potential difference. In one embodiment, free charge is provided before the separation has begun to increase until a point after the minimum separation has been passed. In an alternative embodiment, free charge is provided before the separation has exceeded the maximum separation until a point after the maximum separation has been passed. In an alternative embodiment, free charges are provided before the separation has reached a minimum separation until a point after the maximum separation has been passed.
除了將與氫電漿相關聯的自由電荷用作以上所描述之電荷源以外，在一替代實施例中，自由電荷亦可用以實現靜電夾具100之清潔。 In addition to using the free charges associated with the hydrogen plasma as the charge source described above, in an alternative embodiment, the free charges may also be used to achieve cleaning of the electrostatic clamp 100 .
應理解，粒子可變得沈積於靜電夾具100之表面上，例如沈積於瘤節106之間。此類粒子可對夾具效能有害。舉例而言，此類粒子可促使靜電夾具100之絕緣體與經夾持圖案化器件MA之表面之間的電荷轉移。此電荷轉移可產生靜電夾具100之額外黏著，即使已自電極移除夾持電壓時亦如此。舉例而言，粒子可變得沈積至絕緣體上，從而導致電荷保持於夾具表面處。此經截留電荷可導致在經夾持圖案化器件MA之極化塗層中誘發對應的鏡面電荷。 It will be appreciated that particles may become deposited on the surface of the electrostatic clamp 100 , such as between knobs 106 . Such particles can be detrimental to fixture performance. For example, such particles may facilitate charge transfer between the insulator of the electrostatic clamp 100 and the surface of the clamped patterned device MA. This charge transfer can produce additional sticking of the electrostatic clamp 100 even when the clamping voltage has been removed from the electrodes. For example, particles can become deposited onto the insulator, causing charges to remain at the fixture surface. This trapped charge can result in the induction of a corresponding mirror charge in the polarized coating of the clamped patterned device MA.
應理解，經截留於靜電夾具100之表面上之任何粒子可導致來自此類粒子之尖端(其可具有尖銳特徵)之場發射，從而導致朝向圖案化器件MA之正極化塗層128發射電子串流(假定負偏壓電壓經供應至與該等粒子相鄰之電極)。替代地，可藉由氫之正離子或負離子(或實際上供應 於圖案化器件與靜電夾具100之間的間隙中之任何其他氣體)來轉移電荷。應瞭解，可在可具有超過100MV/m之強度之場中發生穿隧電離。以此方式產生之離子可接著被吸引至圖案化器件MA之極化塗層128。 It will be appreciated that any particles trapped on the surface of the electrostatic clamp 100 may result in field emission from the tips of such particles (which may have sharp features), resulting in the emission of a train of electrons toward the positively polarized coating 128 of the patterned device MA. flow (assuming a negative bias voltage is supplied to the electrode adjacent to the particles). Alternatively, positive or negative ions of hydrogen can be provided (or actually supplied any other gas) in the gap between the patterned device and the electrostatic clamp 100 to transfer charge. It will be appreciated that tunneling ionization can occur in fields that can have strengths in excess of 100 MV/m. The ions generated in this manner may then be attracted to the polarized coating 128 of the patterned device MA.
亦應注意，存在於圖案化器件MA之導電塗層128之表面處的任何粒子將很可能轉移至靜電夾具100之絕緣表面。詳言之，粒子應被理解為在存在交變電場的情況下與黏附至導電表面相比更強地黏附至絕緣表面。 It should also be noted that any particles present at the surface of the conductive coating 128 of the patterned device MA will likely be transferred to the insulating surface of the electrostatic clamp 100 . In particular, particles are understood to adhere more strongly to insulating surfaces than to conductive surfaces in the presence of an alternating electric field.
圖14更詳細地展示粒子與靜電夾具100及圖案化器件MA之帶電表面之間的一些相互作用。詳言之，圖14展示靜電夾具100之一部分及圖案化器件MA之一部分的截面。在夾具/圖案化器件界面之不同部分處更詳細地說明了若干不同粒子相關之事件。在所說明之實施例中，電極104A係負偏壓的，而電極104B係正偏壓的。場線係由實線箭頭F指示。 Figure 14 shows in greater detail some of the interactions between the particles and the electrostatic clamp 100 and the charged surfaces of the patterned device MA. In detail, FIG. 14 shows a cross-section of a portion of the electrostatic clamp 100 and a portion of the patterned device MA. Several different particle related events are described in more detail at different parts of the fixture/patterned device interface. In the illustrated embodiment, electrode 104A is negatively biased and electrode 104B is positively biased. The field lines are indicated by the solid arrow F.
在第一區X中，粒子X1最初與圖案化器件MA之表面相關聯。粒子X1係由在電極104A與圖案化器件MA之表面208之間產生之靜電場推動，以朝向靜電夾具100之本體移動。應理解，粒子X1最初帶正電荷且因此朝向負偏壓電極104A被吸引。 In the first region X, particles X1 are initially associated with the surface of the patterned device MA. Particle X1 is driven by the electrostatic field generated between electrode 104A and surface 208 of patterned device MA to move toward the body of electrostatic clamp 100 . It will be appreciated that particle X1 is initially positively charged and is therefore attracted toward negatively biased electrode 104A.
相似地，另一粒子Y1(此時帶負電荷)在區Y處加以說明。該粒子Y1最初與圖案化器件MA之表面128相關聯，且最初帶負電荷。在電極104B處之正電壓之影響下，粒子Y1朝向靜電夾具100之絕緣表面被推動。 Similarly, another particle Y1 (now negatively charged) is illustrated at region Y. The particle Y1 is initially associated with the surface 128 of the patterned device MA and is initially negatively charged. Under the influence of the positive voltage at electrode 104B, particle Y1 is pushed towards the insulating surface of electrostatic clamp 100.
在區W處，可看到來自粒子W1上之尖銳特徵之場發射造成電子待發射至圖案化器件MA之導電表面128。此製程可導致正電荷W2之區保持在夾具表面處，且亦可導致在帶電粒子與電極之間產生吸引力。 At region W, field emission from the sharp features on particle W1 can be seen causing electrons to be emitted to the conductive surface 128 of the patterned device MA. This process results in a region of positive charge W2 remaining at the surface of the fixture and also results in an attractive force between the charged particles and the electrode.
在區V處，粒子V1位於靜電夾具100之絕緣表面上。穿隧電離可發生於粒子V1處，從而導致產生負離子。詳言之，電子可在由電極104A之極化產生之場下自夾具表面穿隧通過粒子之電位障壁。此製程可導致產生負離子，且正電荷V2保持在夾具表面處。 At region V, particle V1 is located on the insulating surface of electrostatic clamp 100 . Tunneling ionization can occur at particle V1, resulting in the production of negative ions. Specifically, electrons can tunnel from the fixture surface through the potential barrier of particles under the field generated by the polarization of electrode 104A. This process results in the generation of negative ions and the positive charge V2 is maintained at the fixture surface.
在另一區Z中，與夾具100表面相關聯之粒子Z1可經受穿隧電離(例如藉由電子自粒子穿隧至夾具表面)，從而導致產生正離子，且負電荷Z2保持在夾具表面處。在電極104B與圖案化器件MA之間建立的場之影響下，任何此類正離子皆將被吸引至圖案化器件MA。因此，正離子(及相關聯電荷)可被轉移至圖案化器件。 In another zone Z, particles Z1 associated with the surface of the clamp 100 may undergo tunneling ionization (e.g., by electrons tunneling from the particles to the clamp surface), resulting in the generation of positive ions and the negative charge Z2 remaining at the clamp surface . Any such positive ions will be attracted to patterned device MA under the influence of the field established between electrode 104B and patterned device MA. Therefore, positive ions (and associated charges) can be transferred to the patterned device.
應理解，以上參看圖14所描述之各種情境說明可在圖案化器件MA與靜電夾具100之間的界面處發生之若干不同情形，但並非詳盡的。然而，可藉由使用自由電荷源而在一定程度上減輕此等情境中之每一者(及未被說明之其他情境)。舉例而言，電離源(例如VUV源S或EUV源SO)可用作移動電荷源以補償與以上所描述之各種情境相關聯的累積電荷中之一些。此外，電荷補償亦可用以清潔來自靜電夾具之經截留粒子。 It should be understood that the various scenarios described above with reference to FIG. 14 illustrate several different situations that may occur at the interface between the patterned device MA and the electrostatic clamp 100, but are not exhaustive. However, each of these scenarios (and others not illustrated) can be mitigated to some extent by using free charge sources. For example, an ionization source (eg, VUV source S or EUV source SO) can be used as a moving charge source to compensate for some of the accumulated charge associated with the various scenarios described above. In addition, charge compensation can also be used to clean trapped particles from electrostatic clamps.
現在將參看圖15a至圖15e描述藉以可清潔靜電夾具之製程。在圖15a中，再次展示靜電夾具100之一部分。在此實例中，僅展示兩個電極104A、104B。然而，應理解，該靜電夾具100可對應於以上參看圖3所描述之靜電夾具。在圖15a中所展示之初始狀態中，靜電夾具100無偏壓。粒子P1及P2被截留於夾具100之表面上。粒子P1與電極104A相鄰，而粒子P2與電極104B相鄰。電離源S與夾具100相鄰地提供，且最初去激勵使得不發射VUV，且不產生氫電漿。 A process whereby the electrostatic clamp may be cleaned will now be described with reference to Figures 15a-15e. In Figure 15a, a part of the electrostatic clamp 100 is shown again. In this example, only two electrodes 104A, 104B are shown. However, it should be understood that the electrostatic clamp 100 may correspond to the electrostatic clamp described above with reference to FIG. 3 . In the initial state shown in Figure 15a, the electrostatic clamp 100 is unbiased. Particles P1 and P2 are trapped on the surface of the clamp 100 . Particle P1 is adjacent to electrode 104A, and particle P2 is adjacent to electrode 104B. The ionization source S is provided adjacent to the fixture 100 and is initially de-energized so that no VUV is emitted and no hydrogen plasma is generated.
現在參看圖15b，其展示靜電夾具100之清潔製程中之第一 步驟：激勵源S，以便產生電漿P。電漿P橫越靜電夾具100之表面延伸，且隨著距源之距離增加而具有減小之強度。同時，激勵電極104A及104B使得電極104A係負偏壓的，且電極104B係正偏壓的。 Referring now to Figure 15b, a first step in the cleaning process of the electrostatic clamp 100 is shown. Step: Excite source S to generate plasma P. The plasma P extends across the surface of the electrostatic clamp 100 and has decreasing intensity with increasing distance from the source. At the same time, electrodes 104A and 104B are excited such that electrode 104A is negatively biased and electrode 104B is positively biased.
電漿P之自由電荷與施加至夾具100之偏壓結合導致電荷被吸引至夾具100之與電極104A、104B中之每一者相鄰的表面。正電荷Q1與電極104A相鄰地形成，而負電荷Q2與電極104B相鄰地形成。經截留粒子P1、P2將由被吸引至夾具表面之電荷Q1、Q2充電。 The free charge of the plasma P combined with the bias voltage applied to the clamp 100 causes the charge to be attracted to the surface of the clamp 100 adjacent each of the electrodes 104A, 104B. Positive charge Q1 is formed adjacent electrode 104A, while negative charge Q2 is formed adjacent electrode 104B. The trapped particles P1, P2 will be charged by the charges Q1, Q2 attracted to the surface of the clamp.
在以上參看圖15b所描述之製程期間施加至電極104A、104B之電壓可低於典型夾持電壓。舉例而言，夾持電壓可為大約1kV至5kV，而在清潔操作期間供應至電極之電壓可例如介於約0.1kV至2kV之間。 The voltage applied to electrodes 104A, 104B during the process described above with reference to Figure 15b may be lower than the typical clamping voltage. For example, the clamping voltage may be about 1 kV to 5 kV, and the voltage supplied to the electrode during the cleaning operation may be, for example, between about 0.1 kV and 2 kV.
圖15c說明靜電夾具100之清潔製程的另一階段。清潔倍縮光罩160與靜電夾具100相鄰地提供。該清潔倍縮光罩160包含本體162，該本體塗佈有導電層164，且最後塗佈有絕緣層166。絕緣層可由絕緣材料，諸如(例如)Kapton形成。為了將清潔倍縮光罩160夾持至靜電夾具100，可將零電壓施加至電極104A及104B。為了釋放粒子P1、P2，可將電壓暫時施加至電極104A、104B，如圖15c中所展示。然而應注意，在圖15c中所展示之組態中供應之偏壓電壓相對於圖15b中所展示之偏壓電壓反轉。亦即，將正電壓供應至電極104A，而將負電壓供應至電極104B。源S不再被激勵。 Figure 15c illustrates another stage of the cleaning process of the electrostatic clamp 100. A clean reticle 160 is provided adjacent to the electrostatic clamp 100 . The clean reticle 160 includes a body 162 coated with a conductive layer 164 and finally an insulating layer 166 . The insulating layer may be formed from an insulating material such as, for example, Kapton. To clamp the clean reticle 160 to the electrostatic clamp 100, zero voltage may be applied to electrodes 104A and 104B. To release particles P1, P2, a voltage may be temporarily applied to the electrodes 104A, 104B, as shown in Figure 15c. It should be noted, however, that the bias voltage supplied in the configuration shown in Figure 15c is reversed relative to the bias voltage shown in Figure 15b. That is, positive voltage is supplied to electrode 104A, and negative voltage is supplied to electrode 104B. Source S is no longer motivated.
一旦已建立此等新電場，先前存在於夾具100之表面處之任何電荷就將受到施加至電極104A、104B之經反轉偏壓電壓排斥。此將導致粒子P1、P2自夾具表面排斥，且沈積於清潔倍縮光罩160之表面上。 亦即，在圖15b處之充電製程期間累積於粒子P1、P2上的電荷用以使得粒子在圖15c中所展示之步驟中移動。電荷Q1、Q2亦將受到施加至電極104A、104B之電壓排斥。然而，在不存在經由其移動之導電介質的情況下，電荷Q1、Q2可保持於夾具100之表面上。 Once these new electric fields have been established, any charge previously present at the surface of clamp 100 will be repelled by the reverse bias voltage applied to electrodes 104A, 104B. This will cause the particles P1 and P2 to be repelled from the fixture surface and deposited on the surface of the clean reticle 160 . That is, the charge accumulated on the particles P1, P2 during the charging process in Figure 15b is used to cause the particles to move in the steps shown in Figure 15c. Charges Q1, Q2 will also be repelled by the voltage applied to electrodes 104A, 104B. However, charges Q1, Q2 may remain on the surface of clamp 100 in the absence of a conductive medium through which to move.
現在參看圖15d，自靜電夾具100移除清潔倍縮光罩160以及沈積於清潔倍縮光罩160之表面上之粒子P1及P2。為了移除(亦即鬆開)清潔倍縮光罩160，可施加如圖15b中所展示之電壓，亦即，激勵電極104A及104B使得電極104A為負偏壓的，且電極104B為正偏壓的。隨後，如圖15d中所展示，移除施加至電極104A、104B之電壓。應注意，經截留表面電荷Q1、Q2仍可保持於靜電夾具100之表面處。 Referring now to FIG. 15d , the cleaning reticle 160 and the particles P1 and P2 deposited on the surface of the clean reticle 160 are removed from the electrostatic fixture 100 . To remove (i.e., loosen) the cleaning reticle 160, a voltage as shown in Figure 15b may be applied, i.e., electrodes 104A and 104B are energized such that electrode 104A is negatively biased and electrode 104B is positively biased. Pressed. Subsequently, as shown in Figure 15d, the voltage applied to electrodes 104A, 104B is removed. It should be noted that the trapped surface charges Q1 and Q2 can still remain on the surface of the electrostatic clamp 100 .
現在轉而參看圖15e，在清潔製程之最終階段中，可藉由再次由源S產生電離場以便提供電漿P來移除存在於夾具100之表面上之任何殘餘電荷。當在不存在施加至電極104A、104B之任何偏壓的情況下提供電漿P時，靜電夾具100之表面上之殘餘電荷Q1、Q2可由該電漿之自由空間電荷中和。亦即，夾具100之絕緣體上之任何殘餘電荷可被移除。 Turning now to Figure 15e, in the final stage of the cleaning process, any residual charge present on the surface of fixture 100 can be removed by generating an ionization field again from source S to provide plasma P. When plasma P is provided in the absence of any bias applied to electrodes 104A, 104B, residual charges Q1, Q2 on the surface of electrostatic clamp 100 may be neutralized by the free space charge of the plasma. That is, any residual charge on the insulator of clamp 100 can be removed.
以上所描述之清潔製程亦可藉由亦用於微影曝光之EUV源SO來執行。然而，在以上參看圖14a至圖14e所描述之製程中使用單獨的電離源S而非初級EUV源SO可特別有益，此係由於此允許產生移動電荷(例如氫電漿)以自EUV源SO之操作解耦。另外，使用單獨的源S允許在不可得到EUV之區中或在與EUV源隔離之體積中產生補償移動電荷。此允許在與對於EUV源SO(其可例如在約1Pa至10Pa之壓力下操作)典型的壓力相比更低之壓力下(例如，在介於約0.0001Pa至1Pa之間的壓力下)下執行電荷補償。因而，次級電離源之使用本質上可更清潔(基於存在可用之 較高真空位準)。此外，次級電離源之功率可易於經調諧及最佳化以用於清潔效能。 The cleaning process described above can also be performed with an EUV source SO also used for lithography exposure. However, the use of a separate ionization source S rather than the primary EUV source SO in the process described above with reference to Figures 14a-14e can be particularly beneficial as this allows the generation of mobile charges (eg hydrogen plasma) from the EUV source SO Operational decoupling. Additionally, the use of a separate source S allows the generation of compensating mobile charges in regions where EUV is not available or in a volume isolated from the EUV source. This allows for operation at lower pressures (eg, at a pressure between about 0.0001 Pa and 1 Pa) than is typical for EUV source SO (which may, for example, operate at a pressure of about 1 Pa to 10 Pa) Perform charge compensation. Thus, the use of secondary ionization sources can be inherently cleaner (based on the availability of higher vacuum level). Furthermore, the power of the secondary ionization source can be easily tuned and optimized for cleaning performance.
亦應理解，將靜電夾具之清潔自EUV源SO之操作解耦允許在微影設備之較小體積中，而非在投影系統中進行清潔製程。在並不需要抽空源SO、照明系統IL及投影系統PS之整個體積，且僅夾具經清潔之區需要維持處於真空之較低位準的條件下，此操作促成在較低真空環境中工作之能力。 It will also be appreciated that decoupling the cleaning of the electrostatic fixture from the operation of the EUV source SO allows the cleaning process to be performed in a smaller volume of the lithography equipment rather than in the projection system. This operation facilitates working in a lower vacuum environment without the need to evacuate the entire volume of the source SO, the lighting system IL, and the projection system PS, and only the cleaned areas of the fixture need to be maintained at a lower level of vacuum. ability.
以上所描述之清潔製程包括若干步驟。然而應瞭解，此等步驟並非皆為必需的。舉例而言，可省略清潔倍縮光罩。可藉由在不存在倍縮光罩時倒轉夾具電極之極性來排斥任何經截留電荷。此製程可導致粒子被拋出至夾具周圍之環境中。因而，可較佳在除操作性微影設備之外的環境中進行此製程。可在專業化清潔工具內進行此清潔。 The cleaning process described above includes several steps. It should be understood, however, that not all of these steps are necessary. For example, cleaning the reticle can be omitted. Any trapped charge can be repelled by reversing the polarity of the fixture electrodes when no reticle is present. This process can cause particles to be ejected into the environment surrounding the fixture. Therefore, the process can preferably be performed in an environment other than the operational lithography equipment. This cleaning can be carried out in specialized cleaning tools.
此外，以上所描述之清潔倍縮光罩被描述為包含由面向夾具之薄介電層覆蓋之金屬表面層。然而，金屬層及介電層兩者係可選的。然而應理解，面向夾具之介電層之使用可向入射於清潔倍縮光罩上之任何粒子提供最大粒子黏著力。詳言之，此類帶電粒子將由庫侖吸引力被吸引至介電質表面，且將維持其電荷(歸因於該介電質表面)，從而導致在介電層下方之金屬表面中誘發鏡面電荷。 Additionally, the clean reticle described above is described as comprising a metal surface layer covered by a thin dielectric layer facing the fixture. However, both the metal layer and the dielectric layer are optional. It should be understood, however, that the use of a dielectric layer facing the fixture provides maximum particle adhesion to any particles incident on the clean reticle. Specifically, such charged particles will be attracted to the dielectric surface by Coulomb attraction and will maintain their charge (due to the dielectric surface), resulting in the induction of mirror charges in the metal surface beneath the dielectric layer .
在前述描述中，描述了各種實施例，其中EUV誘發之電漿，或由次級電離源產生之電漿可用以減小微影設備(或相關聯工具)中之高自由空間場可導致問題之範圍。此類自由空間場在EUV功率之斜升期間及在靜電夾具之再極化期間可變得有問題。然而，藉由使用在適當時間產生之自由電荷，如上文所描述，可減輕或避免與此等事件相關聯的負面影 響。 In the foregoing description, various embodiments are described in which EUV-induced plasma, or plasma generated by a secondary ionization source, can be used to reduce problems that can cause high free-space fields in lithography equipment (or associated tools) range. Such free space fields can become problematic during the ramp-up of EUV power and during repolarization of the electrostatic clamp. However, by using free charges generated at appropriate times, as described above, the negative effects associated with such events can be mitigated or avoided. ring.
此外，提供至靜電夾具及圖案化器件之EUV功率之逐漸增加可用以允許任何自由空間場逐漸崩潰，而非提供電荷載流子之突然流入，其可導致高暫態電流及相關聯問題(例如放電、粒子產生)。此效應(亦即，夾具處之EUV功率之逐漸增加)可藉由用以阻擋EUV照射於圖案化器件MA上之遮蔽葉片之逐漸移動引起。此控制可用以調變在夾具之極化期間或在夾具之再極化期間的自由電荷(亦即離子或電子)至夾具之供應。再次，此允許以平滑控制方式移除或減小自由空間場，而非突然改變。 Furthermore, gradual increases in EUV power provided to the electrostatic fixture and patterned device can be used to allow for a gradual collapse of any free space field, rather than providing a sudden influx of charge carriers, which can lead to high transient currents and associated problems (e.g. discharge, particle generation). This effect (ie, the gradual increase in EUV power at the fixture) can be caused by the gradual movement of the masking blades used to block EUV radiation on the patterned device MA. This control can be used to modulate the supply of free charges (ie ions or electrons) to the clamp during polarization of the clamp or during repolarization of the clamp. Again, this allows the free space field to be removed or reduced in a smoothly controlled manner rather than changing abruptly.
另外，可在圖案化器件處置工序(例如，圖案化器件移除)期間使用EUV誘發之電漿或由次級電離器產生之電漿，以防止與電壓放大相關聯的負面影響，該電壓放大係歸因於與各種隔離系統組件之間的增加之分離度相關聯的電容之改變。 Additionally, EUV-induced plasma or plasma generated by a secondary ionizer may be used during patterned device handling processes (e.g., patterned device removal) to prevent negative effects associated with voltage amplification. This is due to changes in capacitance associated with increased separation between the various isolation system components.
此外，自由空間電荷之使用已被論證為提供一種機構，藉由該機構可清潔靜電夾具以便自夾具之表面移除經截留粒子。可與經專門設計之犧牲清潔倍縮光罩結合來執行此製程。 Additionally, the use of free space charges has been demonstrated to provide a mechanism by which electrostatic clamps can be cleaned to remove trapped particles from the surface of the clamp. This process can be performed in conjunction with specially designed sacrificial cleaning reticle masks.
應理解，以上所描述之實施例包括多個顯著優點。此外，在一些實施例中，可在無需修改現有微影系統之結構的情況下達成以上所描述之優點。亦即，在一些實施例中，可以新方式使用現有EUV源，以與通常狀況相比在曝光循環內之不同的時間提供能量。此配置可實施於現有設備中，而無需顯著硬體修改，其中僅具有控制工序之改變。此外，可實施對以上所描述之操作協定之修改之性質，而不顯著影響現有設備之產出率。因而，可在現有曝光循環之間進行操作工序之改變，而對循環長度無顯著影響。 It should be understood that the embodiments described above include a number of significant advantages. Furthermore, in some embodiments, the above-described advantages can be achieved without modifying the structure of the existing lithography system. That is, in some embodiments, existing EUV sources can be used in new ways to provide energy at different times within the exposure cycle compared to normal conditions. This configuration can be implemented in existing equipment without significant hardware modifications, with only changes in the control process. Furthermore, modifications of the nature of the operating protocols described above may be implemented without significantly affecting the throughput of existing equipment. Thus, changes in operating procedures can be made between existing exposure cycles without significant impact on cycle length.
另外，上文所描述之用於清潔靜電夾具之清潔機構可避免或至少減小與經截留於夾具表面上之粒子相關聯的負面結果。亦即，當在經夾持表面之間存在粒子時，經截留粒子(其亦可導致存在經截留電荷)可導致不可預測或漂移的夾持力。 Additionally, the cleaning mechanism described above for cleaning electrostatic clamps can avoid or at least reduce the negative consequences associated with particles trapped on the surface of the clamp. That is, when particles are present between clamped surfaces, trapped particles (which can also result in the presence of trapped charges) can result in unpredictable or drifting clamping forces.
另外，上文所描述之夾具清潔序列可用以在夾具並未用於主動式微影設備內時清潔該夾具。亦即，外部或次級電漿源之使用可確保可有效地清潔夾具，而不干涉微影設備之正常操作。另外，在不依賴於正用以輔助清潔製程之EUV源的條件下，其亦允許在微影設備出於其他目的(例如常規維護)而離線時執行夾具清潔。 Additionally, the fixture cleaning sequence described above may be used to clean the fixture when it is not being used in an active lithography apparatus. That is, the use of an external or secondary plasma source ensures that the fixture can be effectively cleaned without interfering with the normal operation of the lithography equipment. Additionally, it also allows fixture cleaning to be performed while the lithography equipment is offline for other purposes, such as routine maintenance, without relying on the EUV source being used to assist the cleaning process.
如上文所論述，靜電夾具包含電極，該電極被供應有夾持電壓以便產生電場，該電場允許夾持圖案化器件(亦即倍縮光罩)。靜電夾具可包含一對電極：一個正電極及一個負電極。供應至電極之夾持電壓可約為±1kV至10kV，例如±2kV。正電極與負電極之配對意謂圖案化器件之表面處之電壓大致為零，亦即，該等表面保持處於大致處於正電極電壓與負電極電壓中間的電壓。然而，與各種因素相關聯之容差可意謂圖案化器件表面處之電壓與系統之其餘部分相比實際上並不處於零伏特。取而代之，可存在電壓不平衡性，其可導致圖案化器件上之電荷積聚。應瞭解，更一般而言，圖案化器件可被稱作組件。 As discussed above, the electrostatic clamp contains electrodes that are supplied with a clamping voltage in order to create an electric field that allows clamping of the patterned device (ie, the reticle). An electrostatic clamp may contain a pair of electrodes: a positive electrode and a negative electrode. The clamping voltage supplied to the electrodes may be approximately ±1kV to 10kV, such as ±2kV. The pairing of positive and negative electrodes means that the voltage at the surfaces of the patterned device is approximately zero, that is, the surfaces remain at a voltage approximately midway between the positive and negative electrode voltages. However, tolerances associated with various factors can mean that the voltage at the surface of the patterned device is not actually at zero volts compared to the rest of the system. Instead, there can be voltage imbalances that can lead to charge accumulation on the patterned device. It should be understood that, more generally, patterned devices may be referred to as components.
電極塗佈有具有大致100μm之厚度的具有超低熱膨脹係數(例如由Corning製造之ULE®)之材料。如上文所描述，夾具可包含具備突起部(其可被稱作瘤節)之大體上平面表面。該等突起部可確保即使在夾持期間，夾具之大體上平面表面與圖案化器件之夾持表面之間的分離度亦超過最小值(例如10微米)。然而，在夾持期間，應理解，該等突起部之表面 將與經夾持圖案化器件接觸，且因此，在夾持期間，夾具之表面與圖案化器件之表面之間的最小分離度為零。夾具之大體上平面表面與圖案化器件之經夾持表面之間的間距判定電極至圖案化器件之電容耦合。由於高電壓放大器至電極之輸出之容差或個別電極電容之容差(例如，由於塗佈材料(例如ULE)在微米範圍內之變化之厚度)，圖案化器件之表面電位可偏離零直至約10V。作為一實例，在至第一夾持電極之為2kV之高電壓放大器輸出之0.1%容差內的偏差可導致高達4V存在於圖案化器件之表面上。相似地，電極上之塗佈材料之厚度(100μm)之±1μm的偏差(亦即1%)可導致更顯著不平衡性。 The electrodes are coated with a material with an ultra-low coefficient of thermal expansion (such as ULE® manufactured by Corning) with a thickness of approximately 100 μm. As described above, the clamp may include a generally planar surface provided with protrusions, which may be referred to as knobs. The protrusions ensure that even during clamping, the separation between the generally planar surface of the clamp and the clamping surface of the patterned device exceeds a minimum value (eg, 10 microns). However, during clamping, it should be understood that the surface of the protrusions There will be contact with the clamped patterned device, and therefore, the minimum separation between the surface of the clamp and the surface of the patterned device during clamping is zero. The distance between the generally planar surface of the clamp and the clamped surface of the patterned device determines the capacitive coupling of the electrode to the patterned device. Due to tolerances in the output of the high voltage amplifier to the electrodes or tolerances in individual electrode capacitances (e.g., due to varying thicknesses of coating materials (e.g., ULE) in the micron range), the surface potential of a patterned device can deviate from zero up to approximately 10V. As an example, deviations within 0.1% tolerance of a high voltage amplifier output of 2 kV to the first clamp electrode can result in up to 4V being present on the surface of the patterned device. Similarly, a ±1 μm deviation (i.e., 1%) in the thickness of the coating material on the electrode (100 μm) can lead to a more significant imbalance.
與處於非零電壓之圖案化器件相關聯的一個問題為：帶電粒子可被吸引至圖案化器件表面，此可導致成像缺陷。另外，在EUV曝光期間處於非零電壓之圖案化器件可導致電荷累積於圖案化器件之背面處。舉例而言，在EUV接通時段期間，可藉由EUV輻射與存在於掃描器中之氣體之相互作用產生電漿(例如氫電漿)。電漿包含自由電荷(離子)，該等自由電荷由於由夾具產生之電場而可轉移至圖案化器件之表面，尤其是背面。亦即，若圖案化器件之表面在EUV曝光期間處於非零電壓，則在系統之接地部件與該非零圖案化器件之間建立之電位場將致使產生於電漿內之自由電荷流向(或遠離)該圖案化器件，從而導致其變得帶電(帶正電或帶負電)。隨後，當移除夾持電壓時(且當電漿不再存在時)，累積於圖案化器件之表面上之殘餘電荷可繼續存在，從而導致圖案化器件與系統之其他部件(諸如(例如)系統之連接至地面之部件)之間的電位差。 One problem associated with patterned devices at non-zero voltage is that charged particles can be attracted to the surface of the patterned device, which can cause imaging defects. Additionally, patterned devices that are at non-zero voltage during EUV exposure can cause charge to accumulate at the backside of the patterned device. For example, during the EUV on period, a plasma (eg, hydrogen plasma) may be generated by interaction of EUV radiation with gas present in the scanner. The plasma contains free charges (ions) that can be transferred to the surface of the patterned device, especially the backside, due to the electric field generated by the fixture. That is, if the surface of the patterned device is at a non-zero voltage during EUV exposure, the potential field established between the ground component of the system and the non-zero patterned device will cause the free charges generated in the plasma to flow toward (or away from) ) that patterns the device, causing it to become charged (either positively or negatively). Subsequently, when the clamping voltage is removed (and when the plasma is no longer present), the residual charge accumulated on the surface of the patterned device can continue to exist, causing the patterned device to interact with other components of the system, such as (for example) The potential difference between components of the system connected to ground).
如上文所論述，與處於非零電壓之圖案化器件相關聯的另一問題為：在圖案化器件之卸載期間，保持於圖案化器件表面上之任何電 荷會在其中誘發電壓，該電壓隨著圖案化器件移動遠離夾具而顯著放大(且電容因此減小)。此可導致圖案化器件之背面(亦即，面向夾具之側面)與系統之附近接地部件之間的放電。此外，存在於圖案化器件之前表面上之粒子可以高速度自該表面噴射且造成系統內之損壞。因此，需要提供用於減輕上文所闡明之問題中之一或多者之方法。 As discussed above, another problem associated with patterned devices at non-zero voltage is that any voltage remaining on the surface of the patterned device during unloading of the patterned device The charge induces a voltage in it, which amplifies significantly as the patterned device moves away from the fixture (and the capacitance therefore decreases). This can lead to discharges between the backside of the patterned device (ie, the side facing the fixture) and nearby grounded components of the system. Additionally, particles present on the surface prior to patterning the device can be ejected from the surface at high velocities and cause damage within the system. Accordingly, there is a need to provide methods for mitigating one or more of the problems set forth above.
為了解決粒子至圖案化器件(倍縮光罩)之靜電吸引及/或在卸載期間之電壓放大及放電的挑戰，提議使圖案化器件接地(亦即通地)使得與圖案化器件相關聯之淨電壓為零伏特。詳言之，可較佳提供圖案化器件之「虛擬接地」。換言之，可需要藉由調整靜電夾具中之電極之個別電壓而平衡橫越圖案化器件所誘發之電壓以產生總共零伏特，而非向圖案化器件提供實體接地連接。以此方式，不需要額外硬體且不存在實體接地連接丟失之風險。 To address the challenges of electrostatic attraction of particles to the patterned device (reduced mask) and/or voltage amplification and discharge during unloading, it is proposed that the patterned device be grounded (i.e., grounded) such that the patterned device is associated with The net voltage is zero volts. Specifically, a "virtual ground" for patterned devices can be better provided. In other words, rather than providing a physical ground connection to the patterned device, it may be necessary to balance the voltage induced across the patterned device by adjusting the individual voltages of the electrodes in the electrostatic clamp to produce a total of zero volts. This way, no additional hardware is required and there is no risk of losing the physical ground connection.
在用於提供虛擬接地之第一方法中，如圖16中所說明，在步驟200處，例如使用參看圖9a及圖9b所描述之交換總成與靜電夾具相鄰地提供圖案化器件。接著在步驟202處控制靜電夾具，使得圖案化器件夾持至靜電夾具。詳言之，可將第一夾持電壓供應至夾具之第一電極，藉此誘發用以將圖案化器件夾持至夾具之電場。 In a first method for providing a virtual ground, as illustrated in Figure 16, at step 200, a patterned device is provided adjacent an electrostatic clamp, such as using a switch assembly as described with reference to Figures 9a and 9b. Then, at step 202, the electrostatic clamp is controlled so that the patterned device is clamped to the electrostatic clamp. In detail, a first clamping voltage may be supplied to the first electrode of the clamp, thereby inducing an electric field for clamping the patterned device to the clamp.
在步驟204處，使圖案化器件經受EUV輻射之曝光，且接著在步驟206處自靜電夾具附近釋放及移除圖案化器件。如上文所描述，在夾持及曝光期間，電荷可累積於圖案化器件之背面處。亦如尤其參看10至圖13所描述，隨著圖案化器件移動遠離夾具，與圖案化器件之表面(例如圖案化器件之背面)相關聯的電壓可顯著增加。在步驟208處量測此電壓。應瞭解，可替代地量測與圖案化器件之一不同部分相關聯之電壓。舉 例而言，可量測與圖案化器件之正面相關聯之電壓。如上文尤其參看圖12c所論述，正面電壓可小於背面電壓。舉例而言，由於圖案化器件之內部電容，正面電壓可比背面電壓小約五倍。 At step 204, the patterned device is subjected to exposure to EUV radiation, and then at step 206, the patterned device is released and removed from the vicinity of the electrostatic clamp. As described above, charge can accumulate at the backside of the patterned device during clamping and exposure. As also described with particular reference to Figures 10-13, as the patterned device moves away from the fixture, the voltage associated with the surface of the patterned device (eg, the backside of the patterned device) can increase significantly. This voltage is measured at step 208. It will be appreciated that the voltage associated with a different portion of the patterned device may alternatively be measured. Lift For example, the voltage associated with the front side of a patterned device can be measured. As discussed above, particularly with reference to Figure 12c, the front voltage may be smaller than the back voltage. For example, due to the internal capacitance of the patterned device, the front-side voltage can be approximately five times less than the back-side voltage.
基於經量測電壓，在步驟210處判定對第一夾持電壓之調整。應理解，可使用任何經量測之偏移電壓以演算調整電壓。在經判定調整為非零之情況下，在步驟212中，可根據該經判定調整來調整第一夾持電壓。舉例而言，可調整連接至第一電極之高電壓放大器之輸出。應瞭解，可依據待加至電極電壓或自電極電壓減去之電壓，或當前電壓之百分比改變，或高電壓功率放大器之增益之改變，或如對於熟習此項技術者而言顯而易見之任何其他合適項來判定該調整。以此方式，有可能確保圖案化器件中誘發之電壓在零伏特下平衡。 Based on the measured voltage, an adjustment to the first clamping voltage is determined at step 210 . It should be understood that any measured offset voltage may be used to calculate the adjustment voltage. In the event that the determined adjustment is non-zero, in step 212, the first clamping voltage may be adjusted based on the determined adjustment. For example, the output of a high voltage amplifier connected to the first electrode can be adjusted. It should be understood that the voltage to be added to or subtracted from the electrode voltage, or a percentage change in the current voltage, or a change in the gain of a high voltage power amplifier, or any other as is obvious to those skilled in the art appropriate item to determine the adjustment. In this way, it is possible to ensure that the voltage induced in the patterned device is balanced at zero volts.
應瞭解，靜電夾具可包含多於一個電極，詳言之，夾具可包含兩個至n個電極。在此狀況下，步驟210亦包含判定對第二至第n夾持電壓之調整，且步驟212可包含根據經判定調整來調整第二至第n夾持電壓中之任一者或全部。舉例而言，若判定在夾持期間使倍縮光罩表面保持處於+4V之電壓，則可自正及負夾持電極中之每一者之夾持電壓減去4V。替代地，可僅對經組態以引起倍縮光罩表面處之電壓的具有某量值及方向之正(或負)夾持電極進行調整，該倍縮光罩表面如上文所提及處於該等夾持電極之電位之間大體上中間的電壓，以接近零伏特。 It should be understood that the electrostatic clamp may include more than one electrode, and in detail, the clamp may include from two to n electrodes. In this case, step 210 also includes determining adjustments to the second to nth clamping voltages, and step 212 may include adjusting any or all of the second to nth clamping voltages according to the determined adjustments. For example, if it is determined that the reticle surface is maintained at a voltage of +4V during clamping, then 4V can be subtracted from the clamping voltage of each of the positive and negative clamping electrodes. Alternatively, adjustments may be made to only the positive (or negative) clamp electrodes of a certain magnitude and direction configured to induce a voltage at the reticle surface as mentioned above. The voltage approximately midway between the potentials of the clamping electrodes is approximately zero volts.
為了驗證已進行正確調整，可重複該方法。應瞭解，可在驗證方法期間使用同一圖案化器件。替代地，可使用另一圖案化器件。可重複此驗證製程直至判定令人滿意的後果(例如，直至在夾持期間在圖案化器件中誘發之電壓大體上為零，或低於預定臨限值)。 To verify that correct adjustments have been made, repeat the method. It should be understood that the same patterned device can be used during the verification method. Alternatively, another patterned device may be used. This verification process can be repeated until satisfactory results are determined (eg, until the voltage induced in the patterned device during clamping is substantially zero, or below a predetermined threshold).
在一些實施中，在圖案化器件由夾具夾持時進行電壓之量測。圖17中示意性地展示此實施之實例流程圖。可使用圖18中所展示之系統來進行該方法。 In some implementations, the voltage is measured while the patterned device is held by the fixture. An example flow diagram of this implementation is schematically shown in Figure 17. This method can be performed using the system shown in Figure 18.
圖18中所說明之系統基本上對應於圖9a中所展示之系統且在上文加以詳細論述。詳言之，圖18之系統包含圖案化器件MA夾持至之夾具100。在此特定組態中，夾具100包含四個電極104A、104B、104C及104D。經夾持圖案化器件MA被展示為與交換總成150間隔開。圖案化器件MA包含面朝交換總成150之正面126及與夾具100相鄰之背面128。該交換總成包含支撐支撐結構154之交換器件152。交換總成150經組態以使圖案化器件MA朝向及遠離夾具100移動，例如以使能夠用替代圖案化器件交換圖案化器件MA或能夠清潔圖案化器件MA。 The system illustrated in Figure 18 corresponds essentially to the system shown in Figure 9a and discussed in detail above. In detail, the system of Figure 18 includes a fixture 100 to which the patterned device MA is clamped. In this particular configuration, clamp 100 includes four electrodes 104A, 104B, 104C, and 104D. Clamped patterned device MA is shown spaced apart from switch assembly 150 . Patterned device MA includes a front side 126 facing the switch assembly 150 and a back side 128 adjacent the fixture 100 . The switch assembly includes switch devices 152 supporting a support structure 154 . The exchange assembly 150 is configured to move the patterned device MA toward and away from the fixture 100 , for example, to enable the patterned device MA to be exchanged for a replacement patterned device or to enable cleaning of the patterned device MA.
返回參看圖17，在步驟300處，與夾具相鄰地提供圖案化器件。再次，此可使用交換總成150來達成。在後續步驟302處，控制夾具以夾持圖案化器件。詳言之，可將第一夾持電壓供應至夾具之第一電極，藉此誘發用以將圖案化器件夾持至夾具之電場。系統包含電壓監視器180，其經組態以量測與圖案化器件之一部分相關聯之電壓。在此方法之一些實施中，與圖案化器件之一部分相關聯之經量測電壓為正面電壓。在一些實施中，電壓監視器180可為與圖案化器件之正面接觸的交換總成150之一部分，如圖18中所說明。然而，電壓監視器180可位於系統內之任何合適的部位處。在一些實施中，電壓監視器180可為靜電伏特計。靜電伏特計可經配置以在不與圖案化器件之正面接觸的情況下量測與圖案化器件之正面相關聯之電壓，藉此避免電荷在量測期間轉移至圖案化器件(或自圖案化器件轉移)。相似量測配置(亦即使用靜電伏特計)可用以在以 上所描述之離線方法期間量測圖案化器件之正面或背面之電壓。當然應瞭解，圖18中所展示內容僅僅為示意性說明。詳言之，應理解，自電壓監視器180至圖案化器件之正面之所描繪連接用以說明圖案化器件之正面之電壓正被量測，但未必暗示自電壓監視器180至圖案化器件之實體連接。如上文所論述，電壓監視器180可為經配置以量測與圖案化器件之正面相關聯之電壓，而不與其實體接觸的靜電伏特計。 Referring back to Figure 17, at step 300, a patterned device is provided adjacent the fixture. Again, this can be accomplished using the Swap Assembly 150. At subsequent step 302, the clamp is controlled to clamp the patterned device. In detail, a first clamping voltage may be supplied to the first electrode of the clamp, thereby inducing an electric field for clamping the patterned device to the clamp. The system includes a voltage monitor 180 configured to measure a voltage associated with a portion of the patterned device. In some implementations of this method, the measured voltage associated with a portion of the patterned device is a front-side voltage. In some implementations, the voltage monitor 180 may be part of the switch assembly 150 in contact with the front side of the patterned device, as illustrated in FIG. 18 . However, voltage monitor 180 may be located at any suitable location within the system. In some implementations, voltage monitor 180 may be an electrostatic voltmeter. The electrostatic voltmeter can be configured to measure the voltage associated with the front side of the patterned device without contacting the front side of the patterned device, thereby preventing charge transfer to (or from) the patterned device during the measurement. transfer). A similar measurement configuration (i.e. using an electrostatic voltmeter) can be used in the following The voltage on the front or back side of the patterned device is measured during the offline method described above. Of course, it should be understood that what is shown in Figure 18 is only a schematic illustration. In particular, it should be understood that the depicted connection from the voltage monitor 180 to the front side of the patterned device is intended to illustrate that the voltage on the front side of the patterned device is being measured, but does not necessarily imply that the connection from the voltage monitor 180 to the front side of the patterned device is being measured. Entity connection. As discussed above, voltage monitor 180 may be an electrostatic voltmeter configured to measure the voltage associated with the front side of the patterned device without physically contacting it.
與以上所描述之離線方法形成對比，在此實施中，在步驟304期間，在圖案化器件由夾具夾持時，發生電壓量測。基於經量測電壓，在步驟306處判定對第一夾持電壓之調整。若經判定調整為非零，則在步驟308處調整第一夾持電壓。在調整步驟308之後，該方法返回至量測與圖案化器件之部分相關聯的電壓之步驟。量測電壓且判定調整。以此方式，可驗證是否已對第一夾持電壓進行合適調整。應瞭解，若經判定調整為零，則方法可在步驟306之後結束。替代地，可在適當時間間隔下採取進一步電壓量測以確保虛擬接地保持正確。舉例而言，可在EUV曝光之間藉由與圖案化器件相鄰地提供交換總成，而不自夾具移除圖案化器件來週期性地執行進一步量測。 In contrast to the offline approach described above, in this implementation, during step 304, the voltage measurement occurs while the patterned device is held by the fixture. Based on the measured voltage, an adjustment to the first clamping voltage is determined at step 306 . If it is determined that the adjustment is non-zero, the first clamping voltage is adjusted at step 308. After the adjustment step 308, the method returns to the step of measuring the voltage associated with the portion of the patterned device. Measure the voltage and determine the adjustment. In this way, it can be verified whether the first clamping voltage has been appropriately adjusted. It should be understood that if the adjustment is determined to be zero, the method may end after step 306. Alternatively, further voltage measurements can be taken at appropriate intervals to ensure that the virtual ground remains correct. For example, further measurements can be performed periodically between EUV exposures by providing the exchange assembly adjacent to the patterned device without removing the patterned device from the fixture.
應瞭解，在靜電夾具具有多於一個電極(例如兩個至n個電極)，每一電極具有其自有夾持電壓的情況下，步驟306亦可包含基於經量測電壓判定對第二…第n夾持電壓之調整。同樣地，步驟308可包含根據該經判定調整來調整對第二…第n夾持電壓中之任一者或全部。 It should be understood that in the case where the electrostatic clamp has more than one electrode (for example, two to n electrodes), and each electrode has its own clamping voltage, step 306 may also include determining whether the second... Adjustment of nth clamping voltage. Likewise, step 308 may include adjusting any or all of the second... nth clamping voltages based on the determined adjustment.
應進一步瞭解，步驟300、302、304及306分別對應於圖16中所說明之方法之步驟200、202、208及210。由於即時地執行圖17中所說明之方法，故不需要使圖案化器件經受EUV曝光以便將電荷「固定」 於圖案化器件上之適當位置以供量測，此與在圖16中所說明之離線方法中不同。然而，當然應瞭解，圖17之方法可包括作為可選步驟之EUV曝光。在此狀況下，若電壓監視器180形成交換總成150之部分，則交換總成150將必須包含孔隙以便允許EUV輻射到達經夾持圖案化器件。替代地，若電壓監視器180形成另一系統組件之部分，則交換總成可經移動遠離圖案化器件使得EUV輻射可在不受到交換總成阻礙的情況下到達圖案化器件。應進一步瞭解，可使用由除EUV曝光之外的替代構件產生之自由電荷以將電荷提供至經夾持圖案化器件(例如次級電離源)。 It should be further understood that steps 300, 302, 304 and 306 respectively correspond to steps 200, 202, 208 and 210 of the method illustrated in Figure 16. Since the method illustrated in Figure 17 is performed in real time, there is no need to subject the patterned device to EUV exposure in order to "fix" the charge in place on the patterned device for measurement, unlike in the offline method illustrated in Figure 16. However, it will of course be understood that the method of Figure 17 may include EUV exposure as an optional step. In this case, if the voltage monitor 180 formed part of the switch assembly 150, the switch assembly 150 would have to contain apertures to allow EUV radiation to reach the clamped patterned device. Alternatively, if the voltage monitor 180 forms part of another system component, the switch assembly can be moved away from the patterned device so that the EUV radiation can reach the patterned device without being obstructed by the switch assembly. It will be further understood that free charge generated by alternative means other than EUV exposure can be used to provide charge to the clamped patterned device (eg, a secondary ionization source).
儘管可在本文中特定地參考在IC製造中微影設備之使用，但應理解，本文所描述之微影設備可具有其他應用。可能之其他應用包括製造整合式光學系統、用於磁疇記憶體之導引及偵測圖案、平板顯示器、液晶顯示器(LCD)、薄膜磁頭等。 Although specific reference may be made herein to the use of lithography equipment in IC fabrication, it should be understood that the lithography equipment described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.
儘管可在本文中特定地參考在微影設備之內容背景中之本發明之實施例，但本發明之實施例可用於其他設備中。本發明之實施例可形成光罩檢測設備、度量衡設備或量測或處理諸如晶圓(或其他基板)或光罩(或其他圖案化器件)之物件之任何設備的部件。此等設備通常可被稱作微影工具。此微影工具可使用真空條件或環境(非真空)條件。實際上，本發明之實施例可形成使用靜電夾具的任何設備之部件。 Although specific reference may be made herein to embodiments of the invention in the context of lithography equipment, embodiments of the invention may be used in other equipment. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or a mask (or other patterned device). Such equipment may often be referred to as lithography tools. This lithography tool can be used under vacuum conditions or ambient (non-vacuum) conditions. In fact, embodiments of the present invention may form part of any device using electrostatic clamps.
儘管上文可特定地參考在光學微影之內容背景中對本發明之實施例之使用，但應瞭解，本發明在內容背景允許之情況下不限於光學微影且可用於其他應用(例如壓印微影)中。 Although specific reference may be made above to the use of embodiments of the invention in the context of optical lithography, it will be understood that the invention is not limited to optical lithography and may be used in other applications such as imprinting where the context permits. microshadow) in.
在內容背景允許之情況下，可以硬體、韌體、軟體或其任何組合實施本發明之實施例。本發明之實施例亦可被實施為儲存於機器可 讀媒體上之指令，該等指令可由一或多個處理器讀取及執行。機器可讀媒體可包括用於儲存或傳輸呈可由機器(例如，計算器件)讀取之形式之資訊的任何機構。舉例而言，機器可讀媒體可包括唯讀記憶體(ROM)；隨機存取記憶體(RAM)；磁性儲存媒體；光學儲存媒體；快閃記憶體器件；電、光、聲或其他形式之傳播信號(例如，載波、紅外線信號、數位信號等)；及其他者。另外，韌體、軟體、常式、指令可在本文中被描述為執行某些動作。然而，應瞭解，此類描述僅係出於方便起見，且此等動作事實上起因於計算器件、處理器、控制器或執行韌體、軟體、常式、指令等且在執行此操作時可使致動器或其他器件與實體世界互動之其他器件。 Where the context allows, embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as storing in a machine accessible Read instructions on the media that can be read and executed by one or more processors. Machine-readable media may include any mechanism for storing or transmitting information in a form readable by a machine (eg, a computing device). For example, machine-readable media may include read-only memory (ROM); random-access memory (RAM); magnetic storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of Propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.); and others. In addition, firmware, software, routines, and instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are for convenience only and that such actions are actually caused by the computing device, processor, controller or execution firmware, software, routines, instructions, etc. and when performing such operations Other devices that enable actuators or other devices to interact with the physical world.
雖然上文已描述本發明之特定實施例，但應瞭解，可以與所描述方式不同之其他方式來實踐本發明。以上描述意欲為說明性，而非限制性的。因此，對於熟習此項技術者將顯而易見，可在不脫離下文所闡明之申請專利範圍之範疇的情況下對所描述之本發明進行修改。 While specific embodiments of the invention have been described above, it should be understood that the invention may be practiced otherwise than as described. The above description is intended to be illustrative and not restrictive. Accordingly, it will be apparent to those skilled in the art that modifications can be made to the invention described without departing from the scope of the claims as set forth below.
TA:時段/曝光叢發 T A : time period/exposure burst
TB:時段/曝光叢發 T B : time period/exposure burst
TC:時段/曝光叢發 T C : time period/exposure burst
TD:時段/曝光叢發 T D : time period/exposure burst
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