TWI621921B - Method for forming photoresist patterns - Google Patents
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Abstract
一種形成光阻圖案之方法，首先提供一基底，隨後於該基底上形成一雙層(bi-layered)光阻，該雙層光阻更包含有一第一光阻層與一第二光阻層，該第二光阻層設置於該第一光阻層與該基底之間，該第一光阻層具有一第一折射率，該第二光阻層具有一第二折射率，且該第二折射率大於該第一折射率。在完成該雙層光阻之製作後，進行一微影製程，以圖案化該雙層光阻。A method of forming a photoresist pattern, first providing a substrate, and then forming a bi-layered photoresist on the substrate, the double-layer photoresist further comprising a first photoresist layer and a second photoresist layer The second photoresist layer is disposed between the first photoresist layer and the substrate, the first photoresist layer has a first refractive index, the second photoresist layer has a second refractive index, and the first photoresist layer The secondary refractive index is greater than the first refractive index. After the fabrication of the double-layer photoresist is completed, a lithography process is performed to pattern the double-layer photoresist.
Description
本發明係有關於一種形成光阻圖案之方法，尤指一種採用浸潤式(immersion)曝光製程之形成光阻圖案之方法。The present invention relates to a method of forming a photoresist pattern, and more particularly to a method of forming a photoresist pattern using an immersion exposure process.
在半導體製程的發展中，微影(photolithography)製程一直是最關鍵的步驟之一，其直接關係到後續離子佈植製程與蝕刻製程的品質好壞，與最終形成的半導體元件的可靠度與性能，更影響元件積集度與每一世代的演進。舉例來說，半導體製程已從使用波長為436奈米(nanometer，以下簡稱為nm)的G線紫外光(g-line UV)，發展到使用波長為365 nm、波長為248 nm、以及波長為193 nm的I線紫外光(i-line UV)，以符合半導體元件微縮化趨勢的高解析度要求。In the development of semiconductor manufacturing, the photolithography process has always been one of the most critical steps, which is directly related to the quality of subsequent ion implantation processes and etching processes, and the reliability and performance of the resulting semiconductor components. It also affects the degree of component integration and the evolution of each generation. For example, the semiconductor process has evolved from the use of G-line ultraviolet (g-line UV) with a wavelength of 436 nanometers (hereinafter referred to as nm) to a wavelength of 365 nm, a wavelength of 248 nm, and a wavelength of I-line UV at 193 nm to meet the high resolution requirements of semiconductor component miniaturization.
然而，曝光波長越短時，其能量越強，同時造成的來自底材的反射光也越強。來自底材的反射光係與入射光產生干涉(interference)，而導致臨界尺寸(critical dimension，CD)偏移(shift)，並使得微影製程所產生的轉移圖案不正確，影響到後續佈植製程或蝕刻製程的製程結果。However, the shorter the exposure wavelength, the stronger the energy and the stronger the reflected light from the substrate. The reflected light from the substrate interferes with the incident light, causing a critical dimension (CD) shift and making the transfer pattern produced by the lithography process incorrect, affecting subsequent implantation. Process results for the process or etch process.
為了防止光反射所造成的上述問題，傳統上在形成微影製程所需的光阻之前，係於底材上先形成一多層型態(multilayered)的底部抗反射層(bottom anti-reflective coating，以下簡稱為BARC)，用以吸收部分反射光。BARC的材質多半為無機介電(inorganic dielectric)材料，而採用多層型態的BARC，則是因應曝光製程中採用的UV光波長越來越短，必需用到兩層以上的抗反射層方能有效降低光反射現象，同時避免BARC膜厚控制不易等問題。In order to prevent the above problems caused by light reflection, conventionally, before forming the photoresist required for the lithography process, a multilayered anti-reflective coating is formed on the substrate. , hereinafter referred to as BARC, to absorb partially reflected light. The material of BARC is mostly inorganic dielectric material, and the multi-layer BARC is because the wavelength of UV light used in the exposure process is shorter and shorter, and it is necessary to use more than two layers of anti-reflection layer. Effectively reduce the phenomenon of light reflection, while avoiding the problem of difficult control of BARC film thickness.
熟習該技藝之人士應知，在完成微影製程以及後續的蝕刻製程等之後，通常係將BARC移除，進行後續的其他步驟。因此，仍然需要一種形成光阻圖案的新穎方法，在降低此一短暫存在的膜層成本的同時，不影響微影製程的製程結果以盡量維持微影製程之轉移圖案的正確性。Those skilled in the art will recognize that after completing the lithography process and subsequent etching processes, the BARC is typically removed for subsequent steps. Therefore, there is still a need for a novel method of forming a photoresist pattern that reduces the cost of the film layer that is transiently present without affecting the process results of the lithography process to maintain the correctness of the transfer pattern of the lithography process.
因此，本發明之一目的係在於提供一種可撙節成本又可維持微影製程之轉移圖案正確性的形成光阻圖案的方法。Accordingly, it is an object of the present invention to provide a method of forming a photoresist pattern that is cost-effective and that maintains the correct pattern of the transfer pattern of the lithography process.
根據本發明所提供之申請專利範圍，係提供一種形成光阻圖案之方法。該方法首先提供一基底，隨後於該基底上形成一雙層(bi-layered)光阻，該雙層光阻更包含有一第一光阻層與一第二光阻層，該第二光阻層設置於該第一光阻層與該基底之間，該第一光阻層具有一第一折射率，該第二光阻層具有一第二折射率，且該第二折射率大於該第一折射率。在完成該雙層光阻之製作後，係進行一微影製程，用以圖案化該雙層光阻。In accordance with the scope of the invention provided by the present invention, a method of forming a photoresist pattern is provided. The method first provides a substrate, and then forms a bi-layered photoresist on the substrate, the double-layer photoresist further includes a first photoresist layer and a second photoresist layer, the second photoresist a layer is disposed between the first photoresist layer and the substrate, the first photoresist layer has a first refractive index, the second photoresist layer has a second refractive index, and the second refractive index is greater than the first A refractive index. After the fabrication of the double-layer photoresist is completed, a lithography process is performed to pattern the double-layer photoresist.
根據本發明所提供之形成光阻圖案的方法，係藉由第二光阻層的設置取代複合型態的底部抗反射層。更重要的是，可藉由調整第二光阻層的厚度，使得入射光在第二光阻層與基底產生的反射光會對第一光阻層與第二光阻層之間產生的反射光造呈一破壞性干涉，以此可降低雙層光阻的反射率，故可避免反射光係與入射光產生干涉，並避免臨界尺寸偏移以及微影製程所產生的轉移圖案不正確等問題。According to the method of forming a photoresist pattern provided by the present invention, the bottom anti-reflection layer of the composite type is replaced by the arrangement of the second photoresist layer. More importantly, by adjusting the thickness of the second photoresist layer, the reflected light generated by the incident light on the second photoresist layer and the substrate will reflect between the first photoresist layer and the second photoresist layer. The light creates a destructive interference, which can reduce the reflectivity of the double-layer photoresist, so that the reflected light system can be prevented from interfering with the incident light, and the critical dimension shift and the transfer pattern generated by the lithography process are not correct. .
請參閱第1圖至第6圖，第1圖至第6圖係為本發明所提供之形成光阻圖案的方法之一第一較佳實施例之示意圖。根據本較佳實施例所提供之方法，首先係提供一基底100，基底100可以是一矽基底、含矽基底、或矽覆絕緣(silicon-on-insulator，SOI)基底。基底100內可包含任何半導體元件或金屬導線，且基底100上更可包含其他膜層例如導電層、介電層、或半導體膜層。為了清楚揭示本案之技術特徵，上述元件、導線或膜層等皆未於第1圖中繪示，但熟習該項技藝之人士應知本較佳實施例之基底100可包含該等元件、導線或膜層。Please refer to FIG. 1 to FIG. 6 . FIG. 1 to FIG. 6 are schematic diagrams showing a first preferred embodiment of a method for forming a photoresist pattern provided by the present invention. According to the method provided by the preferred embodiment, a substrate 100 is first provided. The substrate 100 can be a germanium substrate, a germanium-containing substrate, or a silicon-on-insulator (SOI) substrate. Any semiconductor element or metal wire may be included in the substrate 100, and the substrate 100 may further include other film layers such as a conductive layer, a dielectric layer, or a semiconductor film layer. In order to clearly disclose the technical features of the present invention, the above elements, wires or layers are not shown in FIG. 1. Those skilled in the art will appreciate that the substrate 100 of the preferred embodiment may include such components and wires. Or film layer.
請繼續參閱第1圖。接下來，於基底100上形成一底部抗反射單層110，且底部抗反射單層110係覆蓋於於該等元件、導線或膜層之上。底部抗反射單層110係具有一厚度，且該厚度係介於500~2000埃(angstrom)。在本較佳實施例中，底部抗反射單層110係包含一介電材料，例如是氮化矽(silicon nitride，SiN)或氮氧化矽(silicon oxynitride，SiON)，但不限於此。Please continue to see Figure 1. Next, a bottom anti-reflective monolayer 110 is formed on the substrate 100, and the bottom anti-reflective monolayer 110 is overlaid on the elements, wires or layers. The bottom anti-reflective monolayer 110 has a thickness and the thickness is between 500 and 2000 angstroms. In the preferred embodiment, the bottom anti-reflective monolayer 110 comprises a dielectric material such as silicon nitride (SiN) or silicon oxynitride (SiON), but is not limited thereto.
請參閱第1圖與第2圖。在底部抗反射單層110上，係旋轉塗佈(spin coating)一光阻混合物102，光阻混合物102可包含不同物理性質的光阻材料，例如一具有一第一折射率(n1)的第一光阻材料(圖未示)與一具有一第二折射率(n2)的第二光阻材料(圖未示)，且第二折射率係大於第一折射率。此外在本較佳實施例中，第一光阻材料與第二光阻材料係以負型光阻(negative photoresist)材料做為例示。接下來如第2圖所示進行一軟烤(soft baking)步驟120，而光阻混合物102係於軟烤步驟120中自動分層、凝固形成一第一光阻層132與一第二光阻層134，且第一光阻層132與第二光阻層134係組成一雙層(bi-layered)光阻130。如第2圖所示，第二光阻層134係形成於第一光阻層132與基底100之間，即第一光阻層132與底部抗反射單層110之間。在本較佳實施例中，第一光阻層132包含第一光阻材料，故具有該第一折射率；同理第二光阻層134包含第二光阻材料，故具有該第二折射率。Please refer to Figure 1 and Figure 2. On the bottom anti-reflective monolayer 110, a photoresist composition 102 is spin-coated, and the photoresist mixture 102 may comprise a photoresist material having different physical properties, such as a first refractive index (n1). A photoresist material (not shown) and a second photoresist material (not shown) having a second index of refraction (n2), and the second index of refraction is greater than the first index of refraction. In addition, in the preferred embodiment, the first photoresist material and the second photoresist material are exemplified by a negative photoresist material. Next, as shown in FIG. 2, a soft baking step 120 is performed, and the photoresist mixture 102 is automatically layered and solidified in the soft baking step 120 to form a first photoresist layer 132 and a second photoresist. The layer 134 and the first photoresist layer 132 and the second photoresist layer 134 form a bi-layered photoresist 130. As shown in FIG. 2, the second photoresist layer 134 is formed between the first photoresist layer 132 and the substrate 100, that is, between the first photoresist layer 132 and the bottom anti-reflective monolayer 110. In the preferred embodiment, the first photoresist layer 132 includes the first photoresist material and thus has the first refractive index. Similarly, the second photoresist layer 134 includes the second photoresist material, and thus has the second refraction. rate.
請繼續參閱第2圖。第一光阻層132係具有一預定厚度，用以根據微影製程中顯影步驟甚至是後續蝕刻製程的需要提供可有效阻擋蝕刻液的厚度。第二光阻層134則具有一厚度d，厚度d係根據下列相偏移(phase shift)的最小干涉(minimum interference)公式(1)所得：Please continue to see Figure 2. The first photoresist layer 132 has a predetermined thickness for providing a thickness effective to block the etchant according to the development step in the lithography process or even the subsequent etching process. The second photoresist layer 134 has a thickness d which is obtained according to the following phase shift minimum interference formula (1):
(4πnf/λf)d*cosθt=(2m+1)π(4πn f /λ f )d*cosθ t =(2m+1)π
d*cosθt=2m(λf/4nf) (1)d*cosθ t =2m(λ f /4n f ) (1)
其中nf即為第二光阻層134之折射率，λf為顯影製程中曝光步驟所用的光的波長，θt為曝光步驟中光的入射角度，m為曝光步驟中光的節點(node)。由於上述因子在曝光步驟中皆為固定的數值，故可知波的相偏移係與第二光阻層134之厚度d相關。換句話說，可藉由調整第二光阻層134的厚度d，使由第二光阻層134與底部抗反射單層110之間所產生的反射光產生一相偏移。因此，在本較佳實施例中，第二光阻層134係具有一厚度，且該厚度係介於1000~4500埃。Where n f is the refractive index of the second photoresist layer 134, λ f is the wavelength of the light used in the exposure step in the development process, θ t is the incident angle of the light in the exposure step, and m is the node of the light in the exposure step (node ). Since the above factors are all fixed values in the exposure step, it is known that the phase shift of the wave is related to the thickness d of the second photoresist layer 134. In other words, the reflected light generated between the second photoresist layer 134 and the bottom anti-reflective monolayer 110 can be phase-shifted by adjusting the thickness d of the second photoresist layer 134. Therefore, in the preferred embodiment, the second photoresist layer 134 has a thickness and the thickness is between 1000 and 4500 angstroms.
另外，請參閱第3圖與第4圖，第3圖與第4圖係為本較佳實施例之一變化型之示意圖。為了更精確控制雙層光阻130中第一光阻層132與第二光阻層134的厚度，本變化型係如第3圖所示，於底部抗反射單層110上先旋轉塗佈一光阻材料，其包含上述第二折射率。隨後進行一軟烤步驟122，以形成上述具有厚度d的第二光阻層134。接下來如第4圖所示，於第二光阻層134上旋轉塗佈另一光阻材料，其包含上述的第一折射率。隨後再進行一軟烤步驟124，以形成上述的第一光阻層132，構成所需的雙層光阻130。In addition, please refer to FIG. 3 and FIG. 4, and FIG. 3 and FIG. 4 are schematic diagrams showing a variation of the preferred embodiment. In order to more precisely control the thickness of the first photoresist layer 132 and the second photoresist layer 134 in the double-layer photoresist 130, the variation is as shown in FIG. 3, and is first spin-coated on the bottom anti-reflection single layer 110. A photoresist material comprising the above second refractive index. A soft bake step 122 is then performed to form the second photoresist layer 134 having a thickness d as described above. Next, as shown in FIG. 4, another photoresist material is spin-coated on the second photoresist layer 134, which includes the first refractive index described above. A soft bake step 124 is then performed to form the first photoresist layer 132 described above to form the desired double layer photoresist 130.
請參閱第5圖。在利用第1圖與第2圖或第3圖與第4圖所述的方式製備雙層光阻130之後，接下來係進行一微影製程。如熟習該項技藝之人士所示，微影製程係包含一曝光步驟與一顯影步驟，在曝光步驟中，係利用一入射光140，例如波長為248 nm或波長為193 nm的I線紫外光(i-line UV)透過一光罩138照射雙層光阻130。值得注意的是，在曝光步驟中，雙層光阻130的表面，即第一光阻層132的表面係與一周邊介質(ambient medium) 136接觸，周邊介質136具有一第三折射率，且該第三折射率係小於第一光阻層134之第一折射率。周邊介質136可為真空、空氣、氮氣或惰性氣體。此外本較佳實施例中之微影製程較佳為一浸潤式微影製程，因此在曝光步驟中周邊介質136較佳為水。Please refer to Figure 5. After the two-layer photoresist 130 is prepared in the manner described in Figs. 1 and 2 or Figs. 3 and 4, a lithography process is subsequently performed. As shown by those skilled in the art, the lithography process includes an exposure step and a development step in which an incident light 140 is utilized, such as I-line ultraviolet light having a wavelength of 248 nm or a wavelength of 193 nm. The (i-line UV) illuminates the double-layer photoresist 130 through a mask 138. It should be noted that in the exposure step, the surface of the double-layer photoresist 130, that is, the surface of the first photoresist layer 132 is in contact with an ambient medium 136 having a third refractive index, and The third refractive index is smaller than the first refractive index of the first photoresist layer 134. Peripheral medium 136 can be vacuum, air, nitrogen, or an inert gas. In addition, the lithography process in the preferred embodiment is preferably a immersion lithography process, so that the peripheral medium 136 is preferably water during the exposure step.
請繼續參閱第5圖。在曝光步驟中，入射光140係於第一光阻層132與第二光阻層134之間產生一第一反射光142，同時於第二光阻層134與底部抗反射單層110之間產生一第二反射光144。如前所述，本較佳實施例係藉由可藉由調整第二光阻層134的厚度d，使由第二光阻層134與底部抗反射單層110之間所產生的第二反射光144產生一相偏移，再進入第一光阻層132。因此，進入第一光阻層132的第二反射光144與第一反射光142具有一相位差，例如具有一180度(°)的相位差。據此，第二反射光144對第一反射光142係造成一破壞性干涉，抵銷了第一反射光142。值得注意的是，為了表現第一反射光142與第二反射光144的相位差關係，第5圖中係以虛線表示第一反射光142與第二反射光144在第一光阻層132內的行進方向。且為了避免造成混淆，在第5圖中僅繪示一組入射光140與第一反射光142、第二反射光144的關係。Please continue to see Figure 5. In the exposure step, the incident light 140 is coupled between the first photoresist layer 132 and the second photoresist layer 134 to generate a first reflected light 142, and between the second photoresist layer 134 and the bottom anti-reflective monolayer 110. A second reflected light 144 is generated. As described above, the preferred embodiment provides a second reflection between the second photoresist layer 134 and the bottom anti-reflective monolayer 110 by adjusting the thickness d of the second photoresist layer 134. Light 144 produces a phase offset and then enters first photoresist layer 132. Therefore, the second reflected light 144 entering the first photoresist layer 132 has a phase difference from the first reflected light 142, for example, having a phase difference of 180 degrees (°). Accordingly, the second reflected light 144 causes a destructive interference with the first reflected light 142, offsetting the first reflected light 142. It is to be noted that, in order to express the phase difference relationship between the first reflected light 142 and the second reflected light 144, the first reflected light 142 and the second reflected light 144 are indicated by broken lines in the first photoresist layer 132 in FIG. The direction of travel. In order to avoid confusion, only one set of incident light 140 is related to the first reflected light 142 and the second reflected light 144 in FIG.
請參閱第6圖。在完成曝光步驟後，係進行微影製程中的顯影步驟與一硬烤(hard baking)步驟。如前所述，由於本較佳實施例中雙層光阻130係包含負型光阻，因此在顯影步驟與硬烤步驟之後，曝光的部分係被保留下來，而被遮光的部分則被移除，進而於基底100上形成一如第6圖所示之光阻圖案150。之後，係可進行蝕刻製程等必需的半導體製程。然而熟習該項技藝之人士應知，當本較佳實施例中所選用的光阻材料為正型光阻(positive photoresist)時，在顯影步驟與硬烤步驟之後，曝光的部分係被移除，而被遮光的部分則被保留下來，因此將於基底100上形成一與第6圖所示之光阻圖案150互補的光阻圖案(圖未示)。Please refer to Figure 6. After the exposure step is completed, the development step in the lithography process and a hard baking step are performed. As described above, since the double-layer photoresist 130 of the preferred embodiment includes a negative-type photoresist, after the developing step and the hard-baking step, the exposed portion is retained, and the portion that is shielded is moved. In addition, a photoresist pattern 150 as shown in FIG. 6 is formed on the substrate 100. Thereafter, a necessary semiconductor process such as an etching process can be performed. However, those skilled in the art will recognize that when the photoresist material selected in the preferred embodiment is a positive photoresist, the exposed portions are removed after the development step and the hard bake step. The portion that is shielded from light is retained, so that a photoresist pattern (not shown) complementary to the photoresist pattern 150 shown in FIG. 6 is formed on the substrate 100.
根據本第一較佳實施例所提供之形成光阻圖案的方法，係藉由調整第二光阻層134的厚度d，使得入射光140在第二光阻層134與底部抗反射單層110產生的第二反射光144會對第一光阻層132與第二光阻層134之間產生的第一反射光142造成一破壞性干涉，以此降低雙層光阻130的反射率，故可避免第一反射光142與入射光140產生干涉。也因此第二光阻層134的設置係可取代複合型態的底部抗反射層，即基底100上僅需要一底部抗反射單層110。更重要的是，本第一較佳實施例所提供之雙層光阻130係可避免第一反射光142與入射光140因產生干涉，而導致臨界尺寸偏移以及微影製程所產生的轉移圖案不正確等問題。The method for forming a photoresist pattern according to the first preferred embodiment is to adjust the thickness d of the second photoresist layer 134 such that the incident light 140 is in the second photoresist layer 134 and the bottom anti-reflective monolayer 110. The generated second reflected light 144 causes a destructive interference to the first reflected light 142 generated between the first photoresist layer 132 and the second photoresist layer 134, thereby reducing the reflectivity of the double-layer photoresist 130. The first reflected light 142 can be prevented from interfering with the incident light 140. Therefore, the arrangement of the second photoresist layer 134 can replace the bottom anti-reflective layer of the composite pattern, that is, only one bottom anti-reflective monolayer 110 is required on the substrate 100. More importantly, the two-layer photoresist 130 provided in the first preferred embodiment can avoid the interference of the first reflected light 142 and the incident light 140, resulting in a critical dimension shift and a transfer caused by the lithography process. The pattern is incorrect and so on.
請參閱第7圖至第9圖。第7圖至第9圖係為本發明所提供之形成光阻圖案的方法之一第二較佳實施例之示意圖。首先需注意的是，第二較佳實施例中，與第一較佳實施例相同之元件係以相同之符號說明標示。在本較佳實施例中，亦先提供一基底100，例如矽基底、含矽基底、或矽覆絕緣基底等。且在本較佳實施例中基底100係為一將進行一離子佈植製程的基底，因此必需在基底100上形成一光阻圖案，以暴露出部分基底100形成摻雜區，並遮蔽部分基底100，避免離子佈植製程影響基底100的電性。熟習該技藝之人士應知，矽基底具有一鏡面表面(mirror surface)，而此鏡面表面在顯影製程的曝光步驟中會產生大量的反射光，導致嚴重的臨界尺寸偏移問題。然而在離子佈植製程中，任何形成於基底100上的底部抗反射層都會影響離子佈植製程的結果，導致摻雜區輪廓不符預期。Please refer to Figures 7 to 9. 7 to 9 are schematic views showing a second preferred embodiment of the method for forming a photoresist pattern provided by the present invention. It is to be noted that in the second preferred embodiment, the same components as the first preferred embodiment are denoted by the same reference numerals. In the preferred embodiment, a substrate 100 such as a germanium substrate, a germanium-containing substrate, or a germanium insulating substrate is also provided. In the preferred embodiment, the substrate 100 is a substrate that will be subjected to an ion implantation process. Therefore, it is necessary to form a photoresist pattern on the substrate 100 to expose a portion of the substrate 100 to form a doped region and shield a portion of the substrate. 100. Avoiding the ion implantation process affecting the electrical properties of the substrate 100. It will be appreciated by those skilled in the art that the crucible substrate has a mirror surface which produces a large amount of reflected light during the exposure step of the development process, resulting in a severe critical dimension shift problem. However, in the ion implantation process, any bottom anti-reflective layer formed on the substrate 100 affects the result of the ion implantation process, resulting in a misaligned contour of the doped region.
因此，本較佳實施例係直接於基底100上旋轉塗佈一光阻混合物(圖未示)，如前所述光阻混合物可包含不同物理特性的光阻材料，例如一具有一第一折射率的第一光阻材料與一具有一第二折射率的第二光阻材料，且第二折射率係大於第一折射率。此外在本較佳實施例中，第一光阻材料與第二光阻材料亦以正型光阻材料做為例示。接下來如第7圖所示進行一軟烤步驟120，而光阻混合物係於軟烤步驟中自動分層、凝固形成一第一光阻層132與一第二光阻層134，且第一光阻層132與第二光阻層134係組成一雙層光阻130。如第7圖所示，第二光阻層134係形成於第一光阻層132與基底100之間。在本較佳實施例中，第一光阻層132包含第一光阻材料，故具有該第一折射率；同理第二光阻層134包含第二光阻材料，故具有該第二折射率。Therefore, in the preferred embodiment, a photoresist mixture (not shown) is spin-coated directly on the substrate 100. As described above, the photoresist mixture may comprise a photoresist material having different physical properties, for example, having a first refraction. And a rate of the first photoresist material and a second photoresist material having a second index of refraction, and the second index of refraction is greater than the first index of refraction. In addition, in the preferred embodiment, the first photoresist material and the second photoresist material are also exemplified by a positive photoresist material. Next, a soft baking step 120 is performed as shown in FIG. 7, and the photoresist mixture is automatically layered and solidified in the soft baking step to form a first photoresist layer 132 and a second photoresist layer 134, and first. The photoresist layer 132 and the second photoresist layer 134 form a double-layer photoresist 130. As shown in FIG. 7, the second photoresist layer 134 is formed between the first photoresist layer 132 and the substrate 100. In the preferred embodiment, the first photoresist layer 132 includes the first photoresist material and thus has the first refractive index. Similarly, the second photoresist layer 134 includes the second photoresist material, and thus has the second refraction. rate.
如前所述，第一光阻層132係具有一預定厚度，用以根據微影製程中顯影步驟甚至是後續蝕刻製程的需要提供可有效阻擋蝕刻液的厚度。第二光阻層134則具有一厚度d，可由上述的相偏移公式(1)得到。由於波的相偏移係與第二光阻層134之厚度d相關，因此本較佳實施例亦可藉由調整第二光阻層134的厚度d，使由第二光阻層134與底部抗反射單層110之間所產生的反射光產生一相偏移。根據本較佳實施例中，第二光阻層134係具有一厚度，且該厚度係介於1000～4500埃。另外如前所述，為了更精確控制雙層光阻130中第一光阻層132與第二光阻層134的厚度，本較佳實施例亦可在基底100上分別進行旋轉塗佈與軟烤步驟，而依序形成第二光阻層134與第一光阻層132，構成所需的雙層光阻130。As described above, the first photoresist layer 132 has a predetermined thickness for providing a thickness effective to block the etchant according to the development step in the lithography process or even the subsequent etching process. The second photoresist layer 134 has a thickness d which can be obtained by the phase shift formula (1) described above. Since the phase shift of the wave is related to the thickness d of the second photoresist layer 134, the preferred embodiment can also be used to adjust the thickness d of the second photoresist layer 134 from the second photoresist layer 134 to the bottom. The reflected light generated between the anti-reflective monolayers 110 produces a phase shift. According to the preferred embodiment, the second photoresist layer 134 has a thickness of between 1000 and 4500 angstroms. In addition, as described above, in order to more accurately control the thicknesses of the first photoresist layer 132 and the second photoresist layer 134 in the double-layer photoresist 130, the preferred embodiment may also perform spin coating and softness on the substrate 100, respectively. The baking step, and the second photoresist layer 134 and the first photoresist layer 132 are sequentially formed to form a desired double-layer photoresist 130.
請參閱第8圖。在製備完雙層光阻130之後，接下來係進行一微影製程。如熟習該項技藝之人士所示，微影製程係包含一曝光步驟與一顯影步驟，在曝光步驟中，係利用一入射光140，例如波長為248 nm或波長為193 nm的I線紫外光(i-line UV)透過一光罩138照射雙層光阻130。如前所述，雙層光阻130的表面，即第一光阻層132的表面係與一周邊介質136接觸，周邊介質136具有一第三折射率，且該第三折射率係小於第一光阻層134之第一折射率。周邊介質136可為真空、空氣、氮氣或惰性氣體。此外本較佳實施例中之微影製程較佳為一浸潤式微影製程，因此在曝光步驟中周邊介質136較佳為水。Please refer to Figure 8. After the double-layer photoresist 130 is prepared, a lithography process is followed. As shown by those skilled in the art, the lithography process includes an exposure step and a development step in which an incident light 140 is utilized, such as I-line ultraviolet light having a wavelength of 248 nm or a wavelength of 193 nm. The (i-line UV) illuminates the double-layer photoresist 130 through a mask 138. As described above, the surface of the double-layer photoresist 130, that is, the surface of the first photoresist layer 132 is in contact with a peripheral medium 136 having a third refractive index, and the third refractive index is smaller than the first The first refractive index of the photoresist layer 134. Peripheral medium 136 can be vacuum, air, nitrogen, or an inert gas. In addition, the lithography process in the preferred embodiment is preferably a immersion lithography process, so that the peripheral medium 136 is preferably water during the exposure step.
請繼續參閱第8圖。在曝光步驟中，入射光140係於第一光阻層132與第二光阻層134之間產生一第一反射光142，同時於第二光阻層134與基底100之間產生一第二反射光146。如前所述，本較佳實施例係藉由可藉由調整第二光阻層134的厚度d，使由第二光阻層134與基底100之間所產生的第二反射光146產生一相偏移，再進入第一光阻層132。因此，進入第一光阻層132的第二反射光146與第一反射光142具有一相位差，例如具有一180°的相位差。據此，第二反射光146對第一反射光142係造成一破壞性干涉，抵銷了第一反射光142。值得注意的是，為了表現第一反射光142與第二反射光146的相位差關係，第8圖中係以虛線表示第一反射光142與第二反射光146在第一光阻層132內的行進方向。且為了避免造成混淆，在第8圖中僅繪示一組入射光140與第一反射光142、第二反射光146的關係。Please continue to see Figure 8. In the exposure step, the incident light 140 is coupled between the first photoresist layer 132 and the second photoresist layer 134 to generate a first reflected light 142, and a second between the second photoresist layer 134 and the substrate 100. Reflected light 146. As described above, the preferred embodiment generates a second reflected light 146 generated between the second photoresist layer 134 and the substrate 100 by adjusting the thickness d of the second photoresist layer 134. The phase shifts and then enters the first photoresist layer 132. Therefore, the second reflected light 146 entering the first photoresist layer 132 has a phase difference from the first reflected light 142, for example, having a phase difference of 180°. Accordingly, the second reflected light 146 causes a destructive interference with the first reflected light 142, canceling the first reflected light 142. It should be noted that, in order to express the phase difference relationship between the first reflected light 142 and the second reflected light 146, the first reflected light 142 and the second reflected light 146 are indicated by broken lines in the first photoresist layer 132 in FIG. The direction of travel. In order to avoid confusion, only one set of incident light 140 is related to the first reflected light 142 and the second reflected light 146 in FIG.
請參閱第9圖。在完成曝光步驟後，係進行微影製程中的顯影步驟與一硬烤步驟。如前所述，由於本較佳實施例中雙層光阻130係包含正型光阻，因此在顯影步驟與硬烤步驟之後，曝光的部分係被移除，而被遮光的部分則被保留下來，進而於基底100上形成一如第9圖所示之光阻圖案150。之後，係可進行上述的離子佈植製程，以於基底100中形成所需的摻雜區。然而，熟習該項技藝之人士應知，當本較佳實施例中所選用的光阻材料為負型光阻時，在顯影步驟與硬烤步驟之後，曝光的部分係被保留下來，而被遮光的部分則被移除，因此將於基底100上形成一與第9圖所示之光阻圖案150互補的光阻圖案(圖未示)。Please refer to Figure 9. After the exposure step is completed, the development step and a hard baking step in the lithography process are performed. As described above, since the double-layer photoresist 130 of the preferred embodiment includes a positive-type photoresist, after the developing step and the hard-baking step, the exposed portion is removed, and the portion that is shielded is retained. Then, a photoresist pattern 150 as shown in FIG. 9 is formed on the substrate 100. Thereafter, the ion implantation process described above can be performed to form a desired doped region in the substrate 100. However, those skilled in the art will appreciate that when the photoresist material selected in the preferred embodiment is a negative photoresist, the exposed portions are retained after the development step and the hard baking step. The light-shielding portion is removed, so that a photoresist pattern (not shown) complementary to the photoresist pattern 150 shown in FIG. 9 is formed on the substrate 100.
根據本第二較佳實施例所提供之形成光阻圖案的方法，係藉由調整第二光阻層134的厚度d，使得入射光140在第二光阻層134與基底100之間產生的第二反射光146會對第一光阻層132與第二光阻層134之間產生的第一反射光142造成一破壞性干涉，以此降低雙層光阻130以及基底100的反射率，故可避免第一反射光142與入射光140產生干涉。也因此即使基底100具有鏡面表面，且與光阻層之間完全不具有底部抗反射層，仍可藉由第二反射光146造成破壞性干涉抵銷第一反射光142，故本第二較佳實施例所提供之雙層光阻130係可避免第一反射光142與入射光140因產生干涉，而導致臨界尺寸偏移以及微影製程所產生的轉移圖案不正確等問題。The method for forming a photoresist pattern according to the second preferred embodiment is such that the incident light 140 is generated between the second photoresist layer 134 and the substrate 100 by adjusting the thickness d of the second photoresist layer 134. The second reflected light 146 causes a destructive interference to the first reflected light 142 generated between the first photoresist layer 132 and the second photoresist layer 134, thereby reducing the reflectivity of the double-layer photoresist 130 and the substrate 100. Therefore, the first reflected light 142 can be prevented from interfering with the incident light 140. Therefore, even if the substrate 100 has a mirror surface and does not have a bottom anti-reflection layer at all with the photoresist layer, the first reflected light 142 can be offset by the destructive interference caused by the second reflected light 146. The double-layer photoresist 130 provided by the preferred embodiment can avoid the problem that the first reflected light 142 and the incident light 140 interfere with each other, resulting in a critical dimension shift and an incorrect transfer pattern generated by the lithography process.
綜上所述，根據本發明所提供之形成光阻圖案的方法，係藉由第二光阻層的設置取代複合型態的底部抗反射層。更重要的是，可藉由調整第二光阻層的厚度，使得入射光在第二光阻層與基底產生的反射光會對第一光阻層與第二光阻層之間產生的反射光造呈一破壞性干涉，以此可降低雙層光阻的反射率，故可避免反射光係與入射光產生干涉，而導致臨界尺寸偏移以及微影製程所產生的轉移圖案不正確等問題。In summary, the method for forming a photoresist pattern according to the present invention replaces the composite bottom anti-reflective layer by the arrangement of the second photoresist layer. More importantly, by adjusting the thickness of the second photoresist layer, the reflected light generated by the incident light on the second photoresist layer and the substrate will reflect between the first photoresist layer and the second photoresist layer. The light creates a destructive interference, which can reduce the reflectivity of the double-layer photoresist, so that the reflected light system can be prevented from interfering with the incident light, and the critical dimension shift and the transfer pattern generated by the lithography process are incorrect. .
以上所述僅為本發明之較佳實施例，凡依本發明申請專利範圍所做之均等變化與修飾，皆應屬本發明之涵蓋範圍。The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.
100．．．基底100. . . Base
102．．．光阻混合物102. . . Photoresist mixture
110．．．底部抗反射單層110. . . Bottom anti-reflection single layer
120．．．軟烤步驟120. . . Soft baking step
122．．．軟烤步驟122. . . Soft baking step
124．．．軟烤步驟124. . . Soft baking step
130．．．雙層光阻130. . . Double layer photoresist
132．．．第一光阻層132. . . First photoresist layer
134．．．第二光阻層134. . . Second photoresist layer
136．．．周邊介質136. . . Peripheral medium
138．．．光罩138. . . Mask
140．．．入射光140. . . Incident light
142．．．第一反射光142. . . First reflected light
144．．．第二反射光144. . . Second reflected light
146．．．第二反射光146. . . Second reflected light
150．．．光阻圖案150. . . Resistive pattern
第1圖至第6圖係為本發明所提供之形成光阻圖案的方法之一第一較佳實施例之示意圖，其中第3圖與第4圖係為本較佳較佳實施例之一變化型之示意圖。1 to 6 are schematic views of a first preferred embodiment of a method for forming a photoresist pattern provided by the present invention, wherein FIG. 3 and FIG. 4 are one of preferred embodiments of the present invention. A schematic diagram of the variation.
第7圖至第9圖係為本發明所提供之形成光阻圖案的方法之一第二較佳實施例之示意圖。7 to 9 are schematic views showing a second preferred embodiment of the method for forming a photoresist pattern provided by the present invention.
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| TW100122244A TWI621921B (en) | 2011-06-24 | 2011-06-24 | Method for forming photoresist patterns |
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| Country | Link |
|---|---|
| TW (1) | TWI621921B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200406640A (en) * | 2002-10-31 | 2004-05-01 | Taiwan Semiconductor Mfg | AlSixoy as a new bi-layer high transmittance attenuating phase shifting mask material for 193 nanometer lithography |
| TW200941611A (en) * | 2008-02-29 | 2009-10-01 | Freescale Semiconductor Inc | Metrology of bilayer photoresist processes |
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2011
- 2011-06-24 TW TW100122244A patent/TWI621921B/en active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200406640A (en) * | 2002-10-31 | 2004-05-01 | Taiwan Semiconductor Mfg | AlSixoy as a new bi-layer high transmittance attenuating phase shifting mask material for 193 nanometer lithography |
| TW200941611A (en) * | 2008-02-29 | 2009-10-01 | Freescale Semiconductor Inc | Metrology of bilayer photoresist processes |
Also Published As
| Publication number | Publication date |
|---|---|
| TW201300959A (en) | 2013-01-01 |
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