NL2006562A - System and method for pneumatic z supports. - Google Patents

Description

System And Method For Pneumatic Z Supports BACKGROUND

Field of Invention

[0001] Embodiments of the invention generally relates to lithography, and more particularly to reticle supports.

Related Art

[0002] Lithography is widely recognized as a key process in manufacturing integrated circuits (ICs) as well as other devices and/or structures. A lithographic apparatus is a machine, used during lithography, which applies a desired pattern onto a substrate, such as onto a target portion of the substrate. During manufacture of ICs with a lithographic apparatus, a patterning device, which is alternatively referred to as a mask or a reticle, is typically used to generate a circuit pattern to be formed on an individual layer in an IC. This pattern is transferred onto the target portion (e.g., comprising part of, one, or several dies) on the substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (e.g., resist) provided on the substrate. In general, a single substrate contains a network of adjacent target portions that are successively patterned.

[0003] Known lithographic apparatus include steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the "scanning" direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0004] To increase production rate of scanned patterns, a patterning device, e.g., a mask or reticle, is scanned at constant velocity, for example 3 meters/second across a projection lens, back and forth along a scan direction. Therefore, starting from rest, the reticle quickly accelerates to reach the scan velocity, and then at the end of the scan, it quickly decelerates to zero, reverses direction, and accelerates in the opposite direction to reach the scan velocity. The acceleration/deceleration rate is, for example, 15 times the acceleration of gravity. There is no inertial force on the reticle during the constant velocity portion of the scan. However, the large inertial force encountered during the acceleration and deceleration portions of the scan, for example 60 Newtons (=.4 kg of reticle mass x 150 m/sec2 of acceleration) can lead to slippage of the reticle. Such slippage can result in a misaligned device pattern on a substrate.

[0005] Further, the reticle is constrained in the Z axis direction by the use of multiple supports. The function of such supports is to position the reticle in the Z direction while not affecting movement in the X and Y directions. In some configurations the Z supports entail the use of an adhesive to affix a clamp that holds the reticle in place with the remaining support structure, e.g., a chuck. However, the use of adhesive results in significant XY stiffness and large hysteresis issues. Such hysteresis occurs during the acceleration and deceleration portions of the scan when the Z supports, attached to a clamp with adhesive is subject to XY shearing forces where the adhesive, while stiff, exhibits some amount of flexibility and hysteresis in the XY directions. In addition, as these Z supports have a non-zero stiffness factor they also generate a high stress point at the interface of the reticle and clamp in the surrounding regions, thus causing microslip and corresponding overlay issues.

BRIEF SUMMARY

[0006] This section is for the purpose of summarizing some aspects of the invention and to briefly introduce some embodiments of the invention. Simplifications or omissions may be made to avoid obscuring the purpose of the section. Such simplifications or omissions are not intended to limit the scope of the invention.

[0007] Given the aforementioned, what is needed are methods and systems that provide a support system in the Z direction for patterning devices that can function under high acceleration and deceleration with minimal effect on travel and hysteresis in the X and Y directions.

[0008] In an embodiment of the invention a reticle support system includes a reticle clamping system and a pneumatic support system. The reticle clamping system includes a support device and a holding device where the holding device releasably couples a given mask to the support device. The pneumatic support system includes a pressurized channel that provides a pneumatic cushion to support the reticle clamping system in at least the z direction.

[0009] In another embodiment of the invention, there is provided a method for supporting a reticle in the z direction. Such a method includes holding a mask with a support device, producing a pneumatic cushion using a pressurized channel, and supporting the support device using at least the pneumatic cushion in at least the z direction.

[0010] These and other embodiments and features, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. The invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the information contained herein.

BRIEF DESCRIPTION OF THE FIGURES

[0011] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which corresponding reference symbols indicate corresponding parts. Further, the accompanying drawings, which are incorporated herein and form part of the specification, illustrate the embodiments of the invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the relevant art(s) to make and use the invention.

[0012] FIG. 1A is a schematic diagram of a reflective lithographic apparatus, according to an embodiment of the invention.

[0013] FIG. 1B is a schematic diagram of a transmissive lithographic apparatus, according to an embodiment of the invention.

[0014] FIG. 2 is a schematic diagram of a reticle support system, according to an embodiment of the invention.

[0015] FIG. 3 illustrates a side view of a reticle support system without a pneumatic support system.

[0016] FIG. 4 illustrates a side view of a reticle support system with a pneumatic support system, according to an embodiment of the invention.

[0017] FIG. 5 illustrates a side view of a reticle support system with a pneumatic support system and a vacuum exhaust system, according to an embodiment of the invention.

[0018] FIG. 6 illustrates a side view of a reticle support system with a pneumatic support system and a vacuum exhaust system including a baffle containment device, according to an embodiment of the invention.

[0019] FIG. 7 is a flowchart of a method for reticle support using pneumatic support, according to an embodiment of the invention.

[0020] Features of various embodiments will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.

DETAILED DESCRIPTION

[0021] The invention will be better understood from the following descriptions of various “embodiments” of the invention. Thus, specific “embodiments” are views of the invention, but each does not itself represent the whole invention. In many cases individual elements from one particular embodiment may be substituted for different elements in another embodiment carrying out a similar or corresponding function. It is expected that those skilled in the art with access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the invention would be of significant utility.

[0022] The embodiments described herein are referred in the specification as “one embodiment,” “an embodiment,” “an example embodiment,” etc. These references indicate that the embodiment(s) described can include a particular feature, structure, or characteristic, but every embodiment does not necessarily include every described feature, structure, or characteristic. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0023] Embodiments of the invention can be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention can also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g.,, carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc.

[0024] FIG. 1A and FIG. 1B respectively illustrate two exemplary arrangements of lithographic apparatus, namely a lithographic apparatus 100 and lithographic apparatus 100', respectively, in which embodiments of the invention may be implemented. Lithographic apparatus 100 and lithographic apparatus 100' each include the following: an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., DUV or EUV radiation); a support structure (e.g., a mask table) MT configured to support a patterning device (e.g., a mask, a reticle, or a dynamic patterning device) MA and connected to a first positioner PM configured to accurately position the patterning device MA; and, a substrate table (e.g., a wafer table) WT configured to hold a substrate (e.g., a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate W. Lithographic apparatuses 100 and 100' also have a projection system PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion (e.g., comprising one or more dies) C of the substrate W. In lithographic apparatus 100, the patterning device MA and the projection system PS are reflective. In lithographic apparatus 100', the patterning device MA and the projection system PS are transmissive.

[0025] The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation B.

[0026] The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA, the design of the lithographic apparatuses 100 and 100', and other conditions, such as for example whether or not the patterning device MA is held in a vacuum environment. The support structure MT may use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. The support structure MT can be a frame or a table, for example, which can be fixed or movable, as required. The support structure MT can ensure that the patterning device is at a desired position, for example, with respect to the projection system PS. Any use of the terms “reticle” or “mask" herein may be considered synonymous with the more general term “patterning device.”

[0027] The term "patterning device" MA should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section, such as to create a pattern in the target portion C of the substrate W. The pattern imparted to the radiation beam B can correspond to a particular functional layer in a device being created in the target portion C, such as an integrated circuit. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so called assist features. Generally, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit.

[0028] The patterning device MA may be transmissive (as in lithographic apparatus 100’ of FIG. 1B) or reflective (as in lithographic apparatus 100 of FIG. 1A). Examples of patterning devices MA include reticles, masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam B which is reflected by the mirror matrix.

[0029] The term "projection system" PS can encompass various types of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors, such as the use of an immersion liquid or the use of a vacuum. A vacuum environment can be used for EUV or electron beam radiation since other gases can absorb too much radiation or electrons. A vacuum environment can therefore be provided to the whole beam path with the aid of a vacuum wall and vacuum pumps.

[0030] In this embodiment, for example, lithographic apparatus 100 and/or lithographic apparatus 100' can be of a type having two (dual stage) or more substrate tables and for example, two or more mask tables WT. In such “multiple stage” machines, the additional substrate tables WT can be used in parallel or preparatory steps can be carried out on one or more tables while one or more other substrate tables WT are being used for exposure.

[0031] The lithographic apparatus may also be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g., water, so as to fill a space between the projection system and the substrate. An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. The term “immersion” as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that liquid is located between the projection system and the substrate during exposure.

[0032] Referring to FIGS. 1A and 1B, the illuminator IL receives a radiation beam from a radiation source SO. The source SO and the lithographic apparatuses 100, 100' can be separate entities, for example, when the source SO is an excimer laser. In such cases, the source SO is not considered to form part of the lithographic apparatuses 100 or 100', and the radiation beam B passes from the source SO to the illuminator IL with the aid of a beam delivery system BD (in FIG. 1B) including, for example, suitable directing mirrors and/or a beam expander. In other cases, the source SO can be an integral part of the lithographic apparatuses 100, 100'—for example when the source SO is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD, if required, can be referred to as a radiation system.

[0033] The illuminator IL can include an adjuster AD (in FIG. 1B) for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and/or inner radial extent (commonly referred to as "σ-outer" and "σ-inner," respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL can comprise various other components (in FIG. 1B), such as an integrator IN and a condenser CO. The illuminator IL can be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross section.

[0034] Referring to FIG. 1A, the radiation beam B is incident on the patterning device (e.g., mask) MA, which is held on the support structure (e.g., mask table) MT, and is patterned by the patterning device MA. In lithographic apparatus 100, the radiation beam B is reflected from the patterning device (e.g., mask) MA. After being reflected from the patterning device (e.g., mask) MA, the radiation beam B passes through the projection system PS, which focuses the radiation beam B onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF2 (e.g., an interferometric device, linear encoder, or capacitive sensor), the substrate table WT can be moved accurately (e.g., so as to position different target portions C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor IF1 can be used to accurately position the patterning device (e.g., mask) MA with respect to the path of the radiation beam B. Patterning device (e.g., mask) MA and substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2.

[0035] Referring to FIG. 1B, the radiation beam B is incident on the patterning device (e.g., mask MA), which is held on the support structure (e.g., mask table MT), and is patterned by the patterning device. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF (e.g., an interferometric device, linear encoder, or capacitive sensor), the substrate table WT can be moved accurately (e.g., so as to position different target portions C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor (not shown in FIG. 1B) can be used to accurately position the mask MA with respect to the path of the radiation beam B (e.g., after mechanical retrieval from a mask library or during a scan).

[0036] In general, movement of the mask table MT can be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT can be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW.

In the case of a stepper (as opposed to a scanner) the mask table MT can be connected to a short-stroke actuator only or can be fixed. Mask MA and substrate W can be aligned using mask alignment marks M1, M2, and substrate alignment marks P1, P2. Although the substrate alignment marks (as illustrated) occupy dedicated target portions, they can be located in spaces between target portions (known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the mask MA, the mask alignment marks can be located between the dies.

[0037] The lithographic apparatuses 100 and 100' can be used in at least one of the following modes: 1. In step mode, the support structure (e.g., mask table) MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam B is projected onto a target portion C at one time (i.e., a single static exposure). The substrate table WT is then shifted in the X and/or Y direction so that a different target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.

2. In scan mode, the support structure (e.g., mask table) MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam B is projected onto a target portion C (i.e., a single dynamic exposure). The velocity and direction of the substrate table WT relative to the support structure (e.g., mask table) MT can be determined by the (de-)magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width (in the nonscanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion.

3. In another mode, the support structure (e.g., mask table) MT is kept substantially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. In this mode, generally a pulsed radiation source SO can be employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes a programmable patterning device, such as a programmable mirror array of a type as referred to herein.

[0038] Combinations and/or variations on the described modes of use or entirely different modes of use can also be employed.

[0039] Although specific reference can be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein can have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), and thin-film magnetic heads. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms "wafer" or "die" herein can be considered as synonymous with the more general terms “substrate” or “target portion," respectively. The substrate referred to herein can be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool, and/or an inspection tool. Where applicable, the disclosure herein can be applied to such and other substrate processing tools. Further, the substrate can be processed more than once, for example, in order to create a multi-layer 1C, so that the term substrate used herein can also refer to a substrate that already contains multiple processed layers.

[0040] In a further embodiment, lithographic apparatus 100 includes an extreme ultraviolet (EUV) source, which is configured to generate a beam of EUV radiation for EUV lithography. In general, the EUV source is configured in a radiation system (see below), and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0041] In the embodiments described herein, the terms “lens” and “lens element,” where the context allows, can refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components.

[0042] Further, the terms “radiation" and “beam” used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g., having a wavelength λ of 365, 248,193,157 or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (e.g., having a wavelength in the range of 5-20 nm such as, for example, 13.5 nm), or hard X-ray working at less than 5 nm, as well as particle beams, such as ion beams or electron beams. Generally, radiation having wavelengths between about 780-3000 nm (or larger) is considered IR radiation. UV refers to radiation with wavelengths of approximately 100-400 nm. Within lithography, the term "UV" also applies to the wavelengths that can be produced by a mercury discharge lamp: G-line 436 nm; H-line 405 nm; and/or, l-line 365 nm. Vacuum UV, or VUV (i.e., UV absorbed by air), refers to radiation having a wavelength of approximately 100-200 nm. Deep UV (DUV) generally refers to radiation having wavelengths ranging from 126 nm to 428 nm, and in an embodiment, an excimer laser can generate DUV radiation used within a lithographic apparatus. It should be appreciated that radiation having a wavelength in the range of, for example, 5-20 nm relates to radiation with a certain wavelength band, of which at least part is in the range of 5-20 nm.

[0043] FIG. 2 is a schematic diagram of a reticle support system 200, according to an embodiment of the invention.

[0044] In this example, reticle support system 200 includes a holding device 220 to hold a given patterning device 210, a support device 240, and a support transport device 280. Holding device 220 securely holds patterning device 210. Support device 240 supports holding device 220. Support transport device 280 transports support device 240. Support transport device 280 applies an accelerating force to support device 240 during an accelerating portion of a scanning motion profile and a decelerating force to support device 240 during a decelerating portion of a scanning motion profile. Holding device 220 holds patterning device 210, such that during a constant velocity portion of a scanning motion profile there is no displacement of the patterned mask relative to support transport device 280.

[0045] In one example, patterning device 270 (e.g., a mask or reticle) is releasably held to support 240 by holding device 280 (e.g., that uses a vacuum). Support device 240 can be configured to move in both an x-direction and a y-direction while providing controlled support in the z-direction. Support transport device 280 can be coupled to support device 240, e.g., using an adhesive component, such that support transport device 280 provides sufficient force to accellerate support device 240 during an acceleration portion of a scanning motion profile and sufficient force to decelerate support device 240 during a deceleration portion of a scanning motion profile.

[0046] In one example, support transport device 280 may move support device 240 with holding device 220 and the releasably held patterning device 210, at a high rate of speed and a high rate of acceleration or deceleration. High acceleration and deceleration can generate a lateral shearing force between holding device 220 and support device 240. The shearing force can cause slippage of holding device 220 and patterning device 210, relative to support device 240. This lateral force also causes a mechanical hysteresis behavior producing overlay error as the position of patterning device 210 relative to support transport device 280 is not consistent or reproducible.

[0047] FIG. 3 illustrates a conventional reticle support system 300.

[0048] In this example reticle support system 300 includes a holding device 320 to hold a given patterning device 310, adhesives 330, 350, and 360, support device including first and second support device portions 340 and 370, and a support transport device 380.

[0049] In an example, patterning device 310 (e.g., a mask or reticle) is coupled to holding device 320 by a variety of means (e.g., vacuum, adhesive, electo-magnetic, electrostatic). Such a coupling is subject to a variable friction coefficient where such a coefficient varies according to factors such as time and the number of acceleration and deceleration cycles in the xy direction. Holding device 320 is coupled to first support device portion 340 by way of adhesive 330. Adhesive 330 typically exhibits variable stiffness and a variable damping coefficient where the elastic deformation is based on the number of cycles to which adhesive 330 has been exposed. For example, adhesive 330 could be Araldite 2030 with a damping coefficient value of about 20 +/- 5μηι.

[0050] In an example, first support device portion 340 is coupled to second support device portion 370 by the use of adhesive 350 and adhesive 360. Adhesive 350 also exhibits variable stiffness and a variable damping coefficient where the elastic deformation is a function of the number of cycles to which adhesive 350 has been exposed. For example, adhesive 350 could be Araldite 2030 with a damping coefficient value of about 40 +/- 8.5 pm. Adhesive 360 also exhibits variable stiffness and a variable damping coefficient where the elastic deformation is a function of the number of cycles to which adhesive 360 has been exposed. For example, adhesive 360 could be Epo-tek 310M with a damping coefficient value of about 40 +/- 8.5 Mm.

[0051] Because of the damping coefficients discussed above in coupling holding device 320 to support devices 340 and 350, a hysteretic behavior occurs relative to support transport device 380 during xy scan movement. Such hysteretic behavior results in overlay error and microslip issues where accurate placement of patterning device 310 is not reproducible.

[0052] FIG. 4 illustrates a reticle support system 400 including a reticle clamping system and a pneumatic support system, according to an embodiment of the invention.

[0053] In this example while reticle clamping system includes a holding device 420 to hold a given patterning device 410, adhesives 430, 450, 465 and 467, support device including first and second support device portions 440 and 470, a support transport device 480, the pneumatic support system includes a nozzle 475, a pressurized channel 490, and a pneumatic cushion 495.

[0054] In an example, patterning device 410 (e.g., a mask or reticle) is coupled to holding device 420 by a variety of means (e.g., vacuum, adhesive, electo-magnetic, electrostatic). Holding device 420 is coupled to first support device portion 440 by way of adhesive 430. First support device portion 440 is coupled to the second support device portion 470 at only one place by the use of adhesive 450. Notice that first support device portion 440 is only directly coupled to second support device portion 470 by the use of a single area of adhesive 450.

Second support device portion 470 is further coupled to support transport device 480 through the use of adhesive 465.

[0055] As the reticle clamping system only employs a single coupling of first support device portion 440 to second support device portion 470 through the use of the single adhesive 450, an additional support is added consisting of pneumatic cushion 495.

[0056] Pneumatic cushion 495 provides support in the z direction for holding system 420 and patterning device 410. The use of pneumatic cushion 495 provides the z direction support function for patterning device 410 with a nominally zero hysteresis and XY stiffness as the previously shown coupling using adhesive (e.g., adhesive 360) has been eliminated. Elimination of the adhesive coupling also eliminates the associated elastic deformation and damping characteristics of adhesive 360. In addition to eliminating hysteresis and XY stiffness, the use of a pneumatic cushion is insensitive to temperature change, does not use or generate heat, has no fatigue issues, has no moving parts, and no contamination.

[0057] Pneumatic cushion 495 is generated from a pressurized gas, e.g., inert gas, air, or any other type of gas, from pressurized channel 490. Pneumatic cushion 495 creates an upward force in the z direction providing support of support device 440, holding device 420 and patterning device 410. Nozzle 475 shapes the pressurized gas from pressurized channel 490 to form and deliver pneumatic cushion 495 in the gap between nozzle 475 and first support device portion 440. While nozzle 475 is shown as a parallel, non-tapered form, nozzle 475 can be of any shape or size to form a desired pressure and velocity of gas that produces pneumatic cushion 495. In addition, a sensing device, control loop and pressure regulator (not shown) can also be added to reticle support system 400 to provide an active control system to regulate pneumatic cushion 495 in order to maintain support system 440, holding system 420, and patterning system 410 at a desired z position.

[0058] In an embodiment, holding device or system 420 can be a reticle clamp or pad to hold a given reticle or mask and support transport device 480 can be a chuck for use in a lithographic system such as shown in FIGs 1A and 1B.

[0059] FIG. 5 illustrates a reticle support system 500 including a pneunamtic support system and vacuum channels, according to an embodiment of the invention.

[0060] In this example reticle support system 500 includes a holding device 520 to hold a given patterning device 510,, adhesives 530, 550, 565 and 567, support devices 540 and 570, a support transport device 580, a nozzle 575, a pressurized channel 590, a pneumatic cushion 595, and vacuum channels 592 and 594.

[0061] In an example, patterning device 510 (e.g., a mask or reticle) is coupled to holding device 520 by a variety of means (e.g., vacuum, adhesive, electo-magnetic, electrostatic). Holding device 520 is coupled to support device 540 by way of adhesive 530. Support device 540 is coupled to support device 570 by the use of adhesive 550. Support device 570 is further coupled to support transport device 580 through the use of adhesive 565.

[0062] Pneumatic cushion 595 is generated from a pressurized gas, e.g., inert gas, air, or any other type of gas, from pressurized channel 590. Pneumatic cushion 595 creates an upward force in the z direction providing support of support device 540, holding device 520 and patterning device 510. Nozzle 575 shapes the pressurized content from pressurized channel 590 to form and deliver pneumatic cushion 595 in the gap between nozzle 575 and support device 540. Vacuum channels 592 and 594 are shown located within nozzle 575, but could be placed anywhere in the vicinity of nozzle 575. Vacuum channels 592 and 594 provide a system for evacuating pressurized gas from pressurized channel 590 and thus can help control the form of pneumatic cushion 595. In an example, an increased vacuum in vacuum channels 592 and 594 can decrease the upward pneumatic z force produced by pneumatic cushion 595. Therefore, an active system of control using a sensing device, control loop, and pressure regulator could be configured to control both the pressurized channel and the vacuum channels to effectively control the z position of holding system 520 and patterning system 510. While figure 5 depicts two vacuum channels and a single pressurized channel, any number, configuration, or combinations of vacuum and pressurized channels could be used.

[0063] FIG. 6 illustrates a reticle support system 600 including a pneunamtic support system, vacuum channels, and baffles, according to an embodiment of the invention.

[0064] In this example reticle support system 600 includes a holding device 620 to hold a given patterning device 610,, adhesives 630,650, 665 and 667, support devices 640 and 670, a support transport device 680, a nozzle 675, a pressurized channel 690, a pneumatic cushion 695, vacuum channels 692 and 694, and baffles 696 and 698.

[0065] In an example, patterning device 610 (e.g., a mask or reticle) is coupled to holding device 620 by a variety of means (e.g., vacuum, adhesive, electo-magnetic, electrostatic). Holding device 620 is coupled to support device 640 by way of adhesive 630. Support device 640 is coupled to support device 670 by the use of adhesive 650. Support device 670 is further coupled to support transport device 680 through the use of adhesive 665.

[0066] Pneumatic cushion 695 is generated from a pressurized gas, e.g., inert gas, air, or any other type of gas, from pressurized channel 690. Pneumatic cushion 695 creates an upward force in the z direction providing support of support device 640, holding device 620 and patterning device 610. Nozzle 675 shapes the pressurized content from pressurized channel 690 to form and deliver pneumatic cushion 695 in the gap between nozzle 675 and support device 640. Vacuum channels 692 and 694 provide a system for evacuating pressurized gas from pressurized channel 690 and thus can help control the form of pneumatic cushion 695. In addition, baffles 696 and 698 provide an additional level of containment and control of pneumatic cushion 695. However, baffles 696 and 698 are attached to support device 640 and are not in contact with nozzle 675 thus not introducing any type of stiffness, dampening, or elastic deformation.

[0067] FIG. 7 illustrates a flowchart depicting a method 700 for reticle support using a pneumatic cushion, according to an embodiment of the invention. For example, method 700 may be preformed using one or more of the above devices depicted in Figures 1A, 1B, and 4-6.

[0068] In this example, method 700 starts at step 702, and proceeds to step 704. Step 704 includes holding a mask by using a support device. Step 706 provides for producing a pneumatic cushion using a pressurized channel. In step 708 the method provides for supporting the support device using at least the pneumatic cushion in at least the z direction. The method then ends at step 912.

[0069] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as 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.. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or “target portion", respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0070] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

[0071] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g., semiconductor memory, magnetic or optical disk) having such a computer program stored therein.

[0072] For example, software functionalities of a computer system involve programming, including executable codes, may can be used to implement the above described inspection methods. The software code can be executable by a general-purpose computer. In operation, the code and possibly the associated data records can be stored within a general-purpose computer platform. At other times, however, the software may can be stored at other locations and/or transported for loading into an appropriate general-purpose computer system. Hence, the embodiments discussed above involve one or more software products in the form of one or more modules of code carried by at least one machine-readable medium. Execution of such codes by a processor of the computer system enables the platform to implement the functions in essentially the manner performed in the embodiments discussed and illustrated herein.

[0073] As used herein, terms such as computer or machine “readable medium” refer to any medium that participates in providing instructions to a processor for execution. Such a medium can take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) operating as discussed above. Volatile media include dynamic memory, such as main memory of a computer system. Physical transmission media include coaxial cables, copper wire, and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media can take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include, for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, less commonly used media such as punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer can read or send programming codes and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[0074] It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the clauses. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the invention as contemplated by the inventor(s), and thus, are not intended to limit the invention and the appended clauses in any way.

[0075] The invention has been described above with the aid of functional building storing blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building storing blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0076] The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

[0077] The breadth and scope of the invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following clauses and their equivalents. Other aspects of the invention are set out as in the following numbered clauses: 1. A reticle support system, comprising: a reticle clamping system comprising a support device and a holding device, wherein the holding device is configured to releasably couple a given mask to the support device; and a pneumatic support system comprising a pressurized channel configured to provide a pneumatic cushion to support the reticle clamping system in at least the z direction.

2. The system of clause 1, further comprising: a support transport device configured to move the support device.

3. The system of clause 1, wherein the support device provides support for the holding device primarily in the x and y directions.

4. The system of clause 1, wherein the pneumatic support system further comprises a nozzle, wherein the nozzle is coupled, using an adhesive, to the support transport system.

5. The system of clause 4, wherein the pneumatic support system comprises a gap between the nozzle and the support device.

6. The system of clause 1, wherein the pneumatic cushion comprises compressed air.

7. The system of clause 1, further comprising: a sensing device; a control loop; and a pressure regulator, wherein the sensing device, the control loop, and the pressure regulator are configured to provide adjustable control of the pneumatic support system in the z direction.

8. The system of clause 4, the pneumatic support system further comprising: one or more vacuum channels configured to exhaust a portion of the pneumatic cushion from the pressurized channel.

9. The system of clause 8, wherein the vacuum channels are located within the nozzle.

10. The system of clause 1, further comprising: one or more baffles coupled to the support device configured to partially contain the pneumatic cushion.

11. A method for supporting a reticle in the z direction, comprising: holding a mask with a support device; producing a pneumatic cushion using a pressurized channel, supporting the support device using at least the pneumatic cushion in at least the z direction.

12. The method of clause 11, further comprising: moving the support device using a support transport device.

13. The method of clause 11, wherein the supporting the support device is primarily in the x and y directions.

14. The method of clause 11, further comprising directing a pressurized content through a nozzle to produce the pneumatic cushion.

15. The method of clause 14, wherein the pneumatic cushion is formed in a gap between the nozzle and the support device.

16. The method of clause 11, wherein the pneumatic cushion comprises compressed air.

17. The method of clause 11, further comprising: sensing a position of the support device; regulating a pressure of the pneumatic cushion using a control loop to provide adjustable control of the position of the support device.

18. The method of clause 14, further comprising: exhausting a portion of the pneumatic cushion from the pressurized channel using one or more vacuum channels.

19. The method of clause 18, wherein the vacuum channel are located within the nozzle.

20. The method of clause 11, further comprising partially containing the pneumatic cushion using baffles.

Claims (1)

1. Een lithografieinrichting omvattende: een belichtinginrichting ingericht voor het leveren van een stralingsbundel; een drager geconstrueerd voor het dragen van een patroneerinrichting, welke patroneerinrichting in staat is een patroon aan te brengen in een doorsnede van de stralingsbundel ter vorming van een gepatroneerde stralingsbundel; een substraattafel geconstrueerd om een substraat te dragen; en een projectieinrichting ingericht voor het projecteren van de gepatroneerde stralingsbundel op een doelgebied van het substraat, met het kenmerk, dat de substraattafel is ingericht voor het positioneren van het doelgebied van het substraat in een brandpuntsvlak van de projectieinrichting.A lithography device comprising: an exposure device adapted to provide a radiation beam; a carrier constructed to support a patterning device, the patterning device being capable of applying a pattern in a section of the radiation beam to form a patterned radiation beam; a substrate table constructed to support a substrate; and a projection device adapted to project the patterned radiation beam onto a target area of the substrate, characterized in that the substrate table is adapted to position the target area of the substrate in a focal plane of the projection device.