Irradiation-Induced Conductivity Control of Polyimide Films for Reticle Table Cleaning

Abstract

Disclosed herein is a cleaning apparatus for cleaning a reticle stage of a lithographic apparatus. The apparatus includes a substrate having a front surface and a back surface opposite the front surface. A polyimide layer is provided on the front surface of the substrate and configured to contact the reticle stage and remove particles on the reticle stage. The polyimide layer includes radicals therein that provide the polyimide layer with conductivity for dissipating charge on the reticle stage.

Description

[Technical Field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Application No. 63 / 439,310, filed January 17, 2023, which is incorporated herein by reference in its entirety.

[0002] [Technical field] The present disclosure relates to reticle table cleaning (RTC) apparatus, systems and methods, such as charge dissipation and particle removal RTC apparatus for lithographic apparatus and systems. [Background technology]

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus can, for example, image a pattern in a patterning device (e.g., mask or reticle) onto a layer of radiation-sensitive material (resist) provided on the substrate.

[0004] To project a pattern onto a substrate, a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Lithographic apparatuses that use extreme ultraviolet (EUV) radiation, having a wavelength in the range of 4-20 nm, e.g., 6.7 nm or 13.5 nm, can be used to form smaller features on a substrate than lithographic apparatuses that use deep ultraviolet (DUV) radiation, e.g., having a wavelength of 157 nm, 193 nm, or 248 nm.

[0005] Reticle stages used to hold patterning devices in lithographic apparatus can become contaminated (e.g., accumulate particles) over time. Contaminants can be transferred from the reticle stage to the patterning device, for example, by electrostatic clamps that hold the patterning device during patterning. Contaminants can accumulate on the patterning device and cause patterning errors and defects. Contaminated reticle stages can be manually cleaned, but manual cleaning can leave particulate residue. Furthermore, manual cleaning requires venting and partial disassembly of the lithographic apparatus, reducing overall yield.

[0006] Current RTC devices use insulating top coatings that can accumulate charge over multiple cycles (e.g., trapping of charge carriers in the insulating coating). Under vacuum, the RTC device can eventually stick to the reticle stage due to parasitic charges between opposing insulating contact surfaces. When parasitic charges occur, the lithography apparatus must be vented to atmospheric pressure and partially disassembled to manually separate the RTC device from the reticle stage. One way to dissipate the charge between the reticle stage (e.g., electrostatic clamp) and the RTC device is to use a separate conductive device placed between each load of the RTC device. However, this process reduces the scanning capability and overall efficiency of the lithography apparatus due to the need for two devices.

[0007] A conductive front layer has been proposed to reduce and / or eliminate sticking problems between clamp 204 and front layer 410. In a prior solution, PCT Patent Publication WO 2022 / 128750, which is incorporated by reference in its entirety, it has been proposed to achieve this by doping the front layer with various fillers and / or additives. Summary of the Invention [Problem to be solved by the invention]

[0008] There is a need for an efficient and cost-effective conductive RTC device to dissipate charge on the reticle stage and remove particles from the reticle stage, thereby improving the efficiency and overall yield of the lithography apparatus. [Means for solving the problem]

[0009] In one embodiment, the present disclosure provides a cleaning apparatus for cleaning a reticle stage of a lithographic apparatus, the apparatus comprising: a substrate having a front surface and a back surface opposite the front surface; and a polyimide layer disposed on the front surface of the substrate, the polyimide layer configured to contact the reticle stage to remove particles on the reticle stage, the polyimide layer having radicals therein for imparting electrical conductivity to the polyimide for dissipating charge on the reticle stage.

[0010] In some embodiments, the radicals are formed at least in part from broken C-N bonds within the imide groups of the polyimide layer and / or from broken C-O bonds of the polyimide protons when radiation is applied to the C-N, C-O, and phenyl ring chemical bonds of the imide backbone structure.

[0011] In some embodiments, the polyimide layer has a lower stiffness than the substrate and a thickness of 8 microns or less to create an electrostatic field between the polyimide layer and the reticle stage.

[0012] In some embodiments, a chromium nitride layer is provided between the polyimide layer and the substrate. The CrN layer has a much higher conductivity than the polyimide layer, e.g., about 100 S / cm to about 300 S / cm (e.g., about 200 S / cm), and can function to enhance the discharge process by creating a charge gradient from the irradiated polyimide layer. The conductive CrN layer can also be used for reticle clamping purposes.

[0013] In some embodiments, a positioning device is coupled to the backside of the substrate and configured to move the polyimide layer relative to the reticle stage.

[0014] According to another embodiment, there is provided a lithographic apparatus including a cleaning apparatus. In particular, the lithographic apparatus includes an illumination system configured to illuminate a patterning device, a projection system configured to project an image of the patterning device onto a patterning substrate, and a reticle stage configured to support the patterning device, the reticle stage including a chuck and an electrostatic clamp having a plurality of burls. The cleaning apparatus is configured to clean the reticle stage, the cleaning apparatus including a substrate having a front surface and a back surface opposite the front surface, and a polyimide layer provided on the front surface of the substrate and configured to contact the reticle stage to dissipate charge on the reticle stage and remove particles on the reticle stage. The polyimide layer has radicals therein to impart conductivity to the polyimide layer for dissipating charge on the reticle stage.

[0015] In another embodiment, there is provided a method of forming a reticle stage cleaning apparatus for removing particles on a reticle stage in a lithographic apparatus, the method comprising: providing a substrate having a front surface and a back surface opposite the front surface, providing a polyimide layer on the front surface of the substrate, and irradiating the polyimide layer with radiation to increase the conductivity of the polyimide layer.

[0016] In one embodiment, irradiating the polyimide layer forms radicals within the polyimide layer, increasing the conductivity of the polyimide layer.

[0017] In one embodiment, the irradiation comprises using one or more of an electron beam, gamma rays, ultraviolet photons, laser radiation or microwaves.

[0018] In one embodiment, the radicals are formed from vacuum and atmospheric conditions.

[0019] Further features and exemplary aspects of the embodiments, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. It should be noted that the embodiments are not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the relevant art based on the teachings contained herein. [Brief explanation of the drawings]

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate schematic diagrams of embodiments and, together with the description, serve to explain the principles of the embodiments and further assist those skilled in the relevant art in making and using the embodiments.

[0021] [Figure 1] 1 is a schematic diagram of a lithographic apparatus according to an exemplary embodiment;

[0022] [Figure 2] 1 is a schematic perspective view of a reticle stage and a reticle according to an exemplary embodiment;

[0023] [Figure 3] 3 is a schematic cross-sectional view of the reticle stage and reticle shown in FIG. 2.

[0024] [Figure 4] FIG. 1 is a schematic perspective view of an RTC reticle according to an exemplary embodiment.

[0025] [Figure 5] FIG. 5 is a schematic cross-sectional view of the RTC reticle shown in FIG. 4.

[0026] [Figure 6A] 1 illustrates a process cycle for removing particles from a reticle stage to an RTC reticle, according to an exemplary embodiment. [Figure 6B]1 illustrates a process cycle for removing particles from a reticle stage to an RTC reticle, according to an exemplary embodiment. [Figure 6C] 1 illustrates a process cycle for removing particles from a reticle stage to an RTC reticle, according to an exemplary embodiment.

[0027] [Figure 7] FIG. 1 is a schematic perspective view of an RTC reticle according to an exemplary embodiment.

[0028] [Figure 8] FIG. 8 is a schematic cross-sectional view of the RTC reticle shown in FIG. 7.

[0029] [Figure 9] FIG. 1 is a schematic perspective view of a reticle stage and an RTC reticle according to an exemplary embodiment.

[0030] [Figure 10] FIG. 10 is a schematic cross-sectional view of the reticle stage and RTC reticle shown in FIG. 9.

[0031] [Figure 11] 1 shows a manufacturing flow chart for manufacturing an RTC reticle according to an exemplary embodiment.

[0032] [Figure 12] 1 illustrates a cleaning flow chart for removing particles from a reticle stage to an RTC reticle, according to an exemplary embodiment.

[0033] Features and exemplary aspects of the embodiments will become more apparent from the following detailed description when read in conjunction with the drawings. In the drawings, like reference numbers indicate corresponding elements. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. Also, the leftmost digit(s) of a reference number generally indicates the drawing in which the reference number first appears. Unless otherwise noted, the drawings provided throughout this disclosure should not be construed as drawings to scale. DETAILED DESCRIPTION OF THE INVENTION

[0034] This specification discloses one or more embodiments that incorporate features of the present invention. The disclosed embodiments are merely exemplary of the present invention. The scope of the present invention is not limited to the disclosed embodiments. The present invention is defined by the claims appended hereto.

[0035] References to the described embodiments, and to "one embodiment," "an embodiment," "an example embodiment," "an exemplary embodiment," and the like herein, indicate that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments necessarily include the particular feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with one embodiment, it will be understood that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0036] Spatially relative terms such as "bottom," "lower," "lower side," "top," "upper," and "upper" may be used herein to describe and facilitate the relationship of one element or feature to another element or feature as shown in the drawings. These spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the drawings. The device may be oriented differently (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein may likewise be interpreted accordingly.

[0037] As used herein, the terms "about" or "substantially" or "approximately" refer to a given quantity value that can vary based on a particular technique. Based on a particular technique, the terms "about" or "substantially" or "approximately" can refer to values ​​that vary within a range of, for example, 10 to 30% of the given quantity value (e.g., ±10%, ±20%, or ±30% of that value).

[0038] Embodiments of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present disclosure may also be implemented as instructions stored on a machine-readable medium that can be read and executed by one or more processors. A machine-readable medium may 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, and electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.). Furthermore, firmware, software, routines, and / or instructions may be described herein as performing certain operations. However, it should be understood that such description is for convenience and that, in reality, such operations result from a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc.

[0039] However, before describing such embodiments in more detail, it is useful to provide an example environment in which embodiments of the present disclosure may be implemented.

[0040] Typical Lithography System

[0041] 1 shows a lithography system comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate a beam of EUV and / or DUV radiation B and to provide the beam of EUV and / or DUV radiation B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT (e.g., a mask table, reticle table, reticle stage) configured to support a patterning device MA (e.g., a mask, a reticle), a projection system PS, and a substrate table WT configured to support a substrate W.

[0042] The illumination system IL is configured to condition the EUV and / or DUV radiation beam B before it is incident on the patterning device MA. The illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11. Together the facetted field mirror device 10 and the facetted pupil mirror device 11 provide the EUV and / or DUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The illumination system IL may include other mirrors or devices in addition to or instead of the facetted field mirror device 10 and the facetted pupil mirror device 11.

[0043] After being so conditioned, the EUV and / or DUV radiation beam B interacts with the patterning device MA. This interaction may be reflective (as shown), which is preferred in the case of EUV radiation. This interaction may be transmissive, which is preferred in the case of DUV radiation. This interaction results in a patterned EUV and / or DUV radiation beam B'. The projection system PS is configured to project the patterned EUV and / or DUV radiation beam B' onto the substrate W. To this end, the projection system PS may comprise a plurality of mirrors 13, 14 configured to project the patterned EUV and / or DUV radiation beam B' onto the substrate W held by a substrate table WT. The projection system PS may apply a demagnification factor to the patterned EUV and / or DUV radiation beam B' to form an image having smaller features than corresponding features on the patterning device MA. For example, a demagnification factor of 4 or 8 may be applied. Although the projection system PS is shown in Figure 1 as having only two mirrors 13, 14, the projection system PS may include a different number of mirrors (for example, six or eight mirrors).

[0044] The substrate W may include a pattern that has already been formed, in which case the lithographic apparatus LA aligns the image formed by the patterned EUV and / or DUV radiation beam B' with the pattern that has already been formed on the substrate W.

[0045] Typical reticle stage assembly and reticle assembly

[0046] As mentioned above, a reticle stage (e.g., support structure MT) that is used to hold a patterning device (e.g., patterning device MA) in a lithographic apparatus (e.g., lithographic apparatus LA) can become contaminated (e.g., accumulate particles) over time. Contaminants can be transferred from the reticle stage to the patterning device, for example by electrostatic clamps that hold the patterning device during patterning.

[0047] 2 and 3 show various exemplary embodiments of a reticle stage 200 and a reticle 300. Figure 2 is a schematic diagram of the reticle stage 200 and the reticle 300 according to one exemplary embodiment. Figure 3 is a schematic cross-sectional view of the reticle stage 200 and the reticle 300 shown in Figure 2.

[0048] 2 and 3 show a reticle stage 200 according to various exemplary embodiments.

[0049] Reticle stage 200 can be configured to support a patterning device (e.g., reticle 300). Reticle stage 200 can further be configured to support a cleaning apparatus (e.g., RTC reticles 400, 400′, 400″, 400′′, 400″”, 400″”, 400″′′, 400″″ shown in FIGS. 4-14 ). Although reticle stage 200 is shown in FIGS. 2 and 3 as a stand-alone apparatus and / or system, embodiments of the present disclosure may be used with other apparatus and / or systems, such as, but not limited to, lithographic apparatus LA, support structure MT, patterning device MA, reticle 300, and / or RTC reticles 400, 400′, 400″, 400′′, 400″”, 400″′, 400″′′, 400″′″, 400″′″, 400″′″.

[0050] 2 and 3, reticle stage 200 can include clamping chuck 202 and electrostatic clamp 204. Clamping chuck 202 can be configured to support (e.g., via negative pressure) electrostatic clamp 204. Electrostatic clamp 204 can be configured to electrostatically support a patterning device (e.g., reticle 300) and / or a cleaning device (e.g., RTC reticle 400, 400′, 400″, 400′′, 400″, 400″′′, 400″”). For example, applying a voltage to electrostatic clamp 204 can generate an electrostatic field between the object (e.g., reticle 300, RTC reticle 400, 400′, 400″, 400′′, 400″, 400″′′, 400″”) and electrostatic clamp 204 to hold the object.

[0051] 2 and 3, electrostatic clamp 204 can include clamping electrodes 206 (e.g., embedded) and burls 208 (e.g., external protrusions or bumps). In some embodiments, clamping electrodes 206 can be embedded in electrostatic clamp 204 and aligned (e.g., vertically) with burls 208. Clamping electrodes 206 can be configured to generate an electrostatic field between burls 208 and / or an object (e.g., reticle 300, RTC reticle 400, 400', 400", 400''', 400"", 400""', 400"""). Burls 208 can be configured to physically contact the object (e.g., reticle 300, RTC reticle 400, 400', 400", 400"', 400"", 400""', 400""") to clamp and hold (e.g., electrostatically) the object.

[0052] As shown in FIG. 2 , in some embodiments, the electrostatic clamp 204 can include various particles or contaminants on its exterior surface (e.g., contact surface). For example, first particles 210 can be present between the burls 208, and second particles 212 can be present on the burls 208. The contaminants (e.g., first particles 210, second particles 212) can accumulate on the electrostatic clamp 204 and can cause patterning errors and / or defects. For example, the contaminants (e.g., first particles 210, second particles 212) can be transferred to the object (e.g., reticle 300, RTC reticle 400, 400′, 400″, 400′′, 400″″, 400″′′, 400″′′) during electrostatic clamping of the object.

[0053] In some embodiments, the electrostatic clamp 204 can be configured to apply a voltage relative to the reticle stage 200 (e.g., the crowbar 208 of the electrostatic clamp 204) to the object (e.g., the reticle 300, the RTC reticle 400, 400′, 400″, 400′′, 400″″, 400″′′, 400″″”). For example, the clamp electrode 206 can apply a voltage difference of 11 V between the reticle stage 200 and the object (e.g., from an applied negative voltage (−Y) or positive voltage (+Y)) to generate an electrostatic field between the reticle stage 200 and the object. The generated electrostatic field generates electrostatic forces (e.g., Lorentz forces) and / or van der Waals forces on the contaminants (e.g., the first particles 210, the second particles 212, etc.), causing transfer of the contaminants from the reticle stage 200 (e.g., the electrostatic clamp 204) to the object.

[0054] 2 and 3 show a reticle 300 according to various exemplary embodiments. Reticle 300 can be configured to generate a patterned radiation beam (e.g., a patterned EUV and / or DUV radiation beam B'). Although reticle 300 is shown in Figures 2 and 3 as a stand-alone apparatus and / or system, embodiments of the present disclosure may be used in conjunction with other apparatus and / or systems, such as, but not limited to, lithographic apparatus LA, support structure MT, reticle stage 200, and / or patterning device MA.

[0055] 2 and 3, reticle 300 can include a patterning device 302 (e.g., patterning device MA) and a backing layer 304. Backing layer 304 can be configured to contact burls 208 of electrostatic clamps 204, allowing reticle stage 200 to hold (e.g., electrostatically) reticle 300 without damaging patterning device 302. Backing layer 304 can be disposed on the backside of patterning device 302. In some embodiments, backing layer 304 can include a polymer or a combination of polymers. For example, backing layer 304 can include polyimide, Viton®, polytetrafluoroethylene (PTFE), Teflon, a fluoropolymer, and / or other materials that are less rigid than patterning device 302.

[0056] Contaminants (e.g., first particle 210, second particle 212) on the electrostatic clamp 204 and / or reticle 300 can cause damage to the electrostatic clamp 204, damage to the reticle 300, and / or patterning errors (e.g., overlay misalignment or voids).

[0057] Typical Reticle Table Cleaning (RTC) Reticle Equipment

[0058] As described above, contaminants (e.g., first particles 210, second particles 212, etc.) can accumulate on the patterning device (e.g., reticle 300) and / or the patterning device support (e.g., reticle stage 200), causing patterning errors and / or defects. While a contaminated reticle stage (e.g., reticle stage 200) can be manually cleaned, manual cleaning can leave particulate residue and potentially introduce new contaminants. Furthermore, manual cleaning requires venting and partial disassembly of the lithography apparatus (e.g., lithography apparatus LA) to atmospheric pressure, thereby reducing overall yield.

[0059] Certain existing RTC devices use insulating top coatings that can accumulate charge over multiple cycles (e.g., trapping of charge carriers in the insulating coating). Under vacuum, the RTC device can eventually stick to the reticle stage due to parasitic charges between opposing insulating contact surfaces. When parasitic charges occur, the lithography apparatus must be vented to atmospheric pressure and partially disassembled to manually separate the RTC device from the reticle stage. One way to dissipate the charge between the reticle stage (e.g., an electrostatic clamp) and the RTC device is to use a separate conductive device placed between each load of the RTC device. However, this process reduces the scanning capability and overall efficiency of the lithography apparatus because two devices are required.

[0060] The RTC reticle apparatus, system, and method embodiments described below can dissipate charge on the reticle stage and remove particles from the reticle stage, improving the efficiency, scanning capability, and overall yield of the lithographic apparatus.

[0061] 4 and 5 show an RTC reticle 400 according to various exemplary embodiments. FIG. 4 is a schematic perspective view of the RTC reticle 400 according to one exemplary embodiment. FIG. 5 is a schematic cross-sectional view (along the plane indicated by line VV in FIG. 4) of the RTC reticle 400 shown in FIG. 4. The RTC reticle 400 can be configured to clean the reticle stage 200 in a lithographic apparatus (e.g., lithographic apparatus LA). The RTC reticle 400 can be further configured to dissipate charge accumulated on the reticle stage 200 (e.g., charge accumulated on the electrostatic clamp 204). The RTC reticle 400 can be further configured to remove contaminants (e.g., first particles 210, second particles 212, etc.) on the reticle stage 200 (e.g., the electrostatic clamp 204) via an electrostatic field generated between the RTC reticle 400 and the reticle stage 200. Although the RTC reticle 400 is shown in Figures 4 and 5 as a stand-alone apparatus and / or system, embodiments of the present disclosure may be used in conjunction with other apparatus and / or systems, such as a lithographic apparatus LA, a support structure MT, a reticle stage 200, a patterning device MA, and / or a reticle 300.

[0062] 4 and 5, the RTC reticle 400 can include a front surface 402, a back surface 404, a substrate 406, a first front surface layer 410, and / or a positioning device 430. The RTC reticle 400 has a front surface 402 and a back surface 404 opposite the front surface 402. The front surface 402 is configured to contact the reticle stage 200. For example, the front surface 402 can contact the burls 208 of the electrostatic clamp 204. In some embodiments, the substrate 406 can be disposed between the first front surface layer 410 and the positioning device 430. In some embodiments, the substrate 406 can be an insulator. For example, the substrate 406 can be fused silica, quartz, silicon oxide, silicon, glass, ceramic, a semiconductor, and / or a combination thereof.

[0063] The first front surface layer 410 can be configured to contact the reticle stage 200 (e.g., the burrs 208 of the electrostatic clamp 204) to dissipate charge accumulated on the reticle stage 200. The first front surface layer 410 can also be configured to contact the reticle stage 200 (e.g., the burrs 208 of the electrostatic clamp 204) to remove contaminants (e.g., the first particles 210, the second particles 212, etc.). The first front surface layer 410 can be provided on the front surface (e.g., the front surface 402) of the substrate 406. In some embodiments, the first front surface layer 410 can be conductive. In one embodiment, a more conductive front surface layer 410 is provided to reduce and / or eliminate sticking issues between the clamp 204 and the front surface layer 410. Additionally, to achieve the desired clamping action (e.g., to generate an electrostatic field between the first front layer 410 and the reticle stage 200), it is desirable to maintain a controlled thickness of the front layer, for example, about 8 μm or less.

[0064] Previous solutions, such as PCT Patent Publication WO 2022 / 128750, have proposed achieving this by doping the front layer with various fillers and / or additives. In one embodiment of the present disclosure, the front layer 410 is a conductive polyimide layer. While polyimides are typically insulators, the conductivity of the polyimide layer 410 can be controlled (increased) by irradiating the polyimide material. For example, irradiation of the polyimide layer 410 can be performed with an electron beam, gamma rays, ultraviolet photons, laser radiation, or any combination thereof, to adjust the degree of conductivity of the polyimide layer (or front layer) 410.

[0065] Before irradiation, the typical conductivity of virgin polyimide is about 10 -18 S / cm (i.e., units Siemens / cm=1 / (Ωcm)). According to one embodiment, by irradiating with a sufficient dose of radiation, the conductivity of polyimide can be increased to a minimum of 10 -11 In another embodiment, the conductivity of the polyimide is increased to at least 10 [S / cm]. -3 [S / cm].

[0066] The ability to alter the conductivity of polyimide materials has been established in various scientific publications. See, for example, Review of Radiation-Induced Effects in Polyimide, Appl. Sci. 2019, 9, 1999; doi:10.3390 / app9101999 (incorporated by reference in its entirety). In one embodiment, a polyimide layer is irradiated with 90 keV protons.

[0067] In one embodiment, irradiation of polyimides induces bond cleavage of carbonyl (C=O) and aromatic ether (C-O-C) moieties and ring-opening of cyclic imides (CN). UV irradiation of polyimides generates high concentrations of radicals derived from CN bond cleavage within the imide groups and CO bonds in the ethers of the polyimides. Radicals are formed from radiation-induced chemical bonds, such as modified C-N bonds, modified CO bonds, and modified phenyl rings on the imide backbone.

[0068] In one embodiment, the UV-generated radicals are located near the surface of the polyimide layer, for example, within a depth of about 500 nm from the surface. In one embodiment, deep UV radiation is used to irradiate the polyimide layer. In one embodiment, the above-mentioned deep UV beam B can be directed or focused during the RTC irradiation process to irradiate the front polyimide layer 410 and generate radicals therein.

[0069] In some embodiments, the first front surface polyimide layer 410 has a stiffness that is less than the stiffness of the substrate 406. For example, the first front surface layer 410 can have a stiffness of 50 N / m, and the substrate 406 can have a stiffness of 1800 N / m. In some embodiments, the first front surface layer 410 can be substantially planar. For example, as shown in FIGS. 4 and 5, the first front surface layer 410 can be planar (e.g., of uniform thickness).

[0070] In some embodiments, the first front surface layer 410 has a thickness of about 8 microns or less to create an electrostatic field between the first front surface layer 410 and the reticle stage 200 .

[0071] In some embodiments, first front layer 410 functions as a leakage capacitor that can dissipate charge within one second. In addition, both layer 410 and layer 406 can function as leakage capacitors. Layer 406 can also accelerate the discharge process and improve the efficiency of the overall RTC process.

[0072] In some embodiments, the RTC reticle 400 can optionally include a second front layer 412 disposed between the first front layer 410 and the substrate 406. For example, as shown in FIGS. 7 and 8, the second front layer 412 can be insulating (e.g., an insulating polymer) and disposed below the first front layer 410 (e.g., a conductive metal and / or conductive polymer). As will be appreciated, in some embodiments, the first front layer 410 can function as a passive conductor (e.g., the first front layer 410 can be maintained at ground or 0V). For example, the clamping electrode 206 of the electrostatic clamp 204 can supply a voltage to the crowbar 208 relative to the first front layer 410, generating an electrostatic field between the electrostatic clamp 204 and the first front layer 410. In one embodiment, the two front layers 410 and 412 can function as "class layers," and a conductivity gradient can be provided within the layer 410 due to height differences caused by the irradiation process.

[0073] The positioning device 430 can be configured to move the first front layer 410 relative to the reticle stage 200. For example, the positioning device 430 can move the first front layer 410 along a vertical direction (e.g., the Z-axis) toward the burls 208 of the electrostatic clamp 204. In some embodiments, the positioning device 430 can be a six-axis motion stage with six degrees of freedom (e.g., X, Y, Z, yaw, pitch, and roll). For example, the positioning device 430 can be configured to bring the RTC reticle 400 (e.g., the first front layer 410) into contact with a first surface region of the reticle stage 200, retract the RTC reticle 400 from the first surface region, move the RTC reticle 400 to a second surface region of the reticle stage 200, and bring the RTC reticle (e.g., the first front layer 410) into contact with the second surface region of the reticle stage 200. In some embodiments, the positioning device 430 can include one or more linear motors (e.g., servo motors). In some embodiments, the positioning device 430 can be located on the backside 404 of the RTC reticle 400. For example, as shown in FIGS. 4 and 5, the substrate 406 can be disposed on the positioning device 430. In some embodiments, the positioning device 430 can be a swap device for loading one or more reticles (e.g., the RTC reticle 400) into the electrostatic clamp 204.

[0074] Typical Process Cycle

[0075] 6A-6C illustrate a process cycle 600 for removing contaminants (e.g., first particles 210, second particles 212, etc.) from reticle stage 200 to RTC reticle 400 according to various exemplary embodiments. FIG. 6A is a schematic cross-sectional view of reticle stage 200 and RTC reticle 400 in an initial step. FIG. 6B is a schematic cross-sectional view of reticle stage 200 and RTC reticle 400 in a contact step. FIG. 6C is a schematic cross-sectional view of reticle stage 200 and RTC reticle 400 in a retract step.

[0076] 6A , in an initial step, the RTC reticle 400 can be moved close to the burls 208 of the electrostatic clamps 204 of the reticle stage 200 so that the burls 208 face a first front surface layer 410 (e.g., conductive) in a direction substantially perpendicular to the first front surface layer 410. For example, a positioning device 430 can align the first front surface layer 410 with the burls 208 of the electrostatic clamps 204. Contaminants (e.g., first particles 210, second particles 212, etc.) are located on the outer surface of the electrostatic clamps 204.

[0077] 6B , in a contacting step, the RTC reticle 400 can be moved vertically (e.g., along the +Z axis) toward the reticle stage 200 along a contacting direction 602 to physically contact the burls 208 of the electrostatic clamps 204. During the contacting step, a voltage difference can be applied between the RTC reticle 400 and the reticle stage 200 (e.g., by applying a voltage to the clamping electrodes 206 and / or the first front layer 410), generating an electrostatic field between the RTC reticle 400 and the reticle stage 200. The generated electrostatic field generates electrostatic forces (e.g., Lorentz forces) and / or van der Waals forces on the contaminants (e.g., the first particles 210, the second particles 212, etc.), causing the contaminants to move from the reticle stage 200 to the RTC reticle 400. Contaminants (e.g., first particles 210, second particles 212, etc.) contact the first front surface layer 410 and remain on the front surface 402. Additionally, charge accumulated on the electrostatic clamp 204 can dissipate when the first front surface layer 410 (e.g., conductive polyimide containing radicals) contacts the electrostatic clamp 204.

[0078] 6C , in a retraction step, the RTC reticle 400 can move vertically (e.g., along the −Z axis) away from the reticle stage 200 along a retraction direction 604 to retract from the burls 208 of the electrostatic clamp 204. During the retraction step, the front surface 402 of the RTC reticle 400 can retain most or all of the contaminants (e.g., first particles 210, second particles 212, etc.) from the electrostatic clamp 204 on the first front surface layer 410.

[0079] 6B and the retraction step shown in FIG. 6C can be repeated (e.g., multiple cycles) to further transfer (remove) contaminants (e.g., first particles 210, second particles 212, etc.) from the electrostatic clamp 204 to the RTC reticle 400. In some embodiments, a process cycle 600 can include contacting the reticle stage 200 with a first surface region of the RTC reticle 400, retracting the RTC reticle 400, moving the RTC reticle 400 (e.g., via the positioning device 430), and contacting the reticle stage 200 with a second surface region of the RTC reticle 400 that is different from the first surface region.

[0080] Typical alternative RTC reticle devices

[0081] 7-14 show RTC reticles 400′, 400″, 400′′, 400′″, 400″′′, and 400″″″ according to various exemplary embodiments. FIG. 7 is a schematic perspective view of RTC reticle 400′ according to one exemplary embodiment. FIG. 8 is a schematic cross-sectional view (along the plane indicated by line VIII-VIII in FIG. 7) of RTC reticle 400′ shown in FIG. 7. FIG. 9 is a schematic perspective view of reticle stage 200 and RTC reticle 400″″″ according to one exemplary embodiment. FIG. 10 is a schematic cross-sectional view of reticle stage 200 and RTC reticle 400″″″ shown in FIG. 9.

[0082] 7 and 8 illustrate an RTC reticle 400′ according to a particular embodiment. For example, the embodiment of the RTC reticle 400 shown in FIGS. 4 and 5 may be similar to the embodiment of the RTC reticle 400′ shown in FIGS. 7 and 8. Like reference numerals are used to indicate features of the embodiment of the RTC reticle 400 shown in FIGS. 4 and 5 and similar features of the embodiment of the RTC reticle 400′ shown in FIGS. 7 and 8. One difference between the embodiment of the RTC reticle 400 shown in FIGS. 4 and 5 and the embodiment of the RTC reticle 400′ shown in FIGS. 7 and 8 is that the RTC reticle 400′ includes not only the first front layer 410 shown in FIGS. 4 and 5, but also a second front layer 412 disposed between the substrate 406 and the first front layer 410. Although the RTC reticle 400' is shown in Figures 7 and 8 as a stand-alone apparatus and / or system, embodiments of the present disclosure may be used in conjunction with other apparatus and / or systems, such as a lithographic apparatus LA, a support structure MT, a reticle stage 200, a patterning device MA, and / or a reticle 300.

[0083] 7 and 8, the RTC reticle 400′ can include a second front surface layer 412. The second front surface layer 412 can be configured to generate an electrostatic field between the reticle stage 200 and the RTC reticle 400′.

[0084] In some embodiments, the second front layer 412 can be insulating to generate an electrostatic field between the reticle stage 200 and the RTC reticle 400′. For example, the second front layer 412 can include an insulating polymer, a combination of polymers, polyimide, Viton®, PTFE, Teflon, a fluoropolymer, an oxide, a nitride, and / or any other insulating material that has a lower stiffness than the first front layer 410.

[0085] In some embodiments, the second front layer 412 can be electrically conductive. For example, the first front layer 410 can include a metal (e.g., Cr, Au, Ti, Cu, Pt, Ag, etc.), a conductive polymer (e.g., a conductive polyimide (e.g., having radicals generated therein by irradiation), Kapton® XC polyimide, Vespel® SP-202 (DuPont), Upilex (Ube Industries), Cirlex (FRALOCK), Norton (Saint-Gobain), etc.), and / or combinations thereof.

[0086] 9 and 10 illustrate an RTC reticle 400""" according to a particular embodiment. For example, the embodiment of RTC reticle 400 shown in FIGS. 4 and 5 may be similar to the embodiment of RTC reticle 400""" shown in FIGS. 9 and 10. Like reference numerals are used to indicate features of the embodiment of RTC reticle 400 shown in FIGS. 4 and 5 and similar features of the embodiment of RTC reticle 400""" shown in FIGS. 9 and 10. One difference between the embodiment of RTC reticle 400 shown in FIGS. 4 and 5 and the embodiment of RTC reticle 400""" shown in FIGS. 13 and 14 is that the embodiment of RTC reticle 400 shown in FIGS. 4 and 5 includes first front layer recesses 411 formed in first front layer 410' and configured to receive corresponding burls 208 of electrostatic clamps 204. Although RTC reticle 400'''''' is shown in Figures 9 and 10 as a stand-alone apparatus and / or system, embodiments of the present disclosure may be used in conjunction with other apparatus and / or systems, such as lithographic apparatus LA, support structure MT, reticle stage 200, patterning device MA, and / or reticle 300.

[0087] 9 and 10 , the RTC reticle 400″″″ can include a first front surface layer 410′ having a first front surface layer recess 411. The first front surface layer 410′ can be configured to generate an electrostatic field between the reticle stage 200 and the RTC reticle 400″″″. The first front surface layer 410′ can further be configured to generate an electrostatic field to remove contaminants (e.g., first particles 210, second particles 212, etc.) on the reticle stage 200 (e.g., electrostatic clamp 204). For example, as shown in FIG. 10 , the first front surface recess 411 can receive burls 208, and the first front surface layer 410′ can contact the area between the burls 208 to remove contaminants (e.g., first particles 210) on the electrostatic clamp 204.

[0088] In some embodiments, the first front layer recesses 411 can be arranged in a pattern (e.g., linear, array, spiral, concentric, etc.) aligned with the corresponding burls 208 of the electrostatic clamp 204. For example, as shown in FIGS. 9 and 10, the first front layer recesses 411 can be symmetrically arranged in an array (e.g., 3x4) in the first front layer 410′. In some embodiments, the first front layer recesses 411 can be recesses (voids) in the first front layer 410′. For example, the first front layer recesses 411 can include holes, hollow cuboids, voids, openings, cutouts, and / or any other suitable shaped recesses for receiving the burls 208. In some embodiments, the first front layer recesses 411 can have a diameter (e.g., hole) or diagonal (e.g., hollow cuboid) of about 0.5 mm to about 3 mm. For example, the first front layer recesses 411 can have a diameter of about 1 mm.

[0089] In some embodiments, the first front layer 410′ can be insulating to generate an electrostatic field between the reticle stage 200 and the RTC reticle 400″″″. For example, the first front layer 410′ can include an insulating polymer, a combination of polymers, polyimide, Viton®, PTFE, Teflon®, a fluoropolymer, an oxide, a nitride, and / or any other insulating material. In some embodiments, the burls 208 of the electrostatic clamp 204 are not in contact with the first front layer 410′ but are sandwiched between the burls 208 and the electrostatic clamp 204 to remove contaminants (e.g., first particles 210) present between the burls 208. 10, burls 208 can be placed within the first front layer recesses 411 to remove first particles 210 between the burls 208. In some embodiments, the depth of the first front layer recesses 411 can be greater than the height of the burls 208. For example, as shown in FIG. 10, the first front layer 410' can have a thickness such that the burls 208 do not contact the first front layer 410' when placed in the first front layer recesses 411. In some embodiments, the first front layer 410' is formed as irradiated polyimide, as described above.

[0090] Typical Manufacturing Flowchart

[0091] 11 shows a manufacturing flowchart 1500 for manufacturing an RTC reticle as described above, according to an exemplary embodiment. It should be understood that not all of the steps in FIG. 11 are required to practice the disclosure provided herein. Furthermore, some steps may be performed simultaneously, sequentially, and / or in a different order than that shown in FIG. 11.

[0092] The manufacturing flowchart 1500 will be described with reference to Figures 4, 5, and 7 to 10. However, the manufacturing flowchart 1500 is not limited to these embodiments.

[0093] In step 1502, a substrate 406 is provided.

[0094] In step 1504, first surface layer 410 can be deposited on front surface 402 of substrate 406. In some embodiments, first surface layer 410 can be formed by deposition. For example, first surface layer 410 can be formed or deposited by any suitable method, including chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), atomic layer deposition (ALD), pulsed laser deposition (PLD), electron beam physical vapor deposition (EBPVD), sputtering (e.g., RF, electron, potential, chemical), ion beam deposition, spin-on deposition, liquid source mist chemical vapor deposition, and / or other suitable deposition methods. In one embodiment, layer 410 can also be formed by a coating method, such as spin coating, dip coating, and / or other coating methods.

[0095] For example, non-limiting examples of materials for the first front polyimide layer 410 can be Kapton® XC polyimide, Vespel® SP-202, Upilex (Ube Industries), Cirlex (FRALOCK), Norton (Saint-Gobain), and / or combinations thereof. Polyimides can be synthesized in a one- or two-step process. In the two-step process, the first step involves reacting a dianhydride with a diamine in a dipolar aprotic solvent such as N,N-dimethylacetamide (DMAc) or N-methylpyrrolidinone (NMP) at ambient conditions to obtain a polyamic acid. The second step involves cyclizing the polyamic acid to obtain a polyimide. Briefly, these are the synthesis and cyclization of polyamic acid.

[0096] In step 1506, the front polyimide layer 410 is irradiated to increase the conductivity of the polyimide layer. Irradiation of the polyimide layer forms radicals in the polyimide layer, increasing the conductivity of the polyimide layer.

[0097] In one or more embodiments, the irradiating step 1506 includes using one or more of an electron beam, gamma rays, ultraviolet photons, laser radiation, or microwaves.

[0098] In one or more embodiments, irradiation to form radicals is performed under either vacuum or atmospheric conditions. In embodiments in which irradiation is performed under vacuum conditions, such irradiation can be performed within the vacuum environment of the lithographic apparatus LA described above, while in other embodiments, such irradiation can be performed in a different vacuum region outside the apparatus LA. A vacuum pump or other vacuum system can be used to generate the vacuum. In embodiments in which irradiation is performed under atmospheric conditions (e.g., by way of non-limiting example, approximately ±5% of atmospheric pressure), such irradiation can be performed in a region or chamber supplied with an inert gas (e.g., Ar, He, Ne, etc.). FIG. 12 illustrates a cleaning flowchart 1600 for removing contaminants (e.g., first particles 210, second particles 212, etc.) from the reticle stage 200 to the RTC reticle 400, 400′, 400″, 400′′, 400″″, 400″′′, 400″″″, according to an exemplary embodiment. It should be understood that not all of the steps in FIG. 12 are required to practice the disclosure provided herein. Furthermore, some steps may be performed simultaneously, sequentially, and / or in a different order than that shown in FIG. 12. The cleaning flowchart 1600 is described with reference to FIGS. 4-10. However, the cleaning flowchart 1600 is not limited to these exemplary embodiments.

[0099] In step 1602, as shown in the example of FIGS. 4-10, RTC reticles 400, 400', 400", 400'", 400"", 400""', 400""" can be formed to remove contaminants (e.g., first particles 210, second particles 212, etc.) from reticle stage 200. In some embodiments, as shown in FIG. 11, RTC reticles 400, 400', 400", 400"", 400"", 400""', 400""" can be formed using fabrication flowchart 1500.

[0100] In step 1604, as shown in the example of FIG. 6B , the RTC reticle 400, 400′, 400′, 400′′, 400′′, 400′′, 400′′, 400′′, 400′′, 400′′, 400′′, 400′′, 400′′, 400′′′, 400′′′, 400′′′, 400′′′ can be in physical contact with the burls 208 of the electrostatic clamps 204 of the reticle stage 200 such that the burls 208 face a first front layer 410 (e.g., conductive) in a substantially vertical direction. For example, the positioning device 430 can align the first front layer 410 with the burls 208 of the electrostatic clamps 204. In some embodiments, the RTC reticle 400, 400′, 400″, 400′′, 400″”, 400″′′, 400″′″, 400″′″ can be in physical contact with the burls 208 of the electrostatic clamp 204 of the reticle stage 200 such that the burls 208 face the second front layer 412′, 412″ (e.g., conductive) in a substantially vertical direction. For example, the positioning device 430 can align the second front layer 412′, 412″ with the burls 208 of the electrostatic clamp 204.

[0101] In step 1606, as shown in the example of FIG. 6B , one or more electrostatic fields can be generated between the RTC reticle 400, 400′, 400″, 400′′, 400′″, 400′′′, 400′′′, 400′′′′, and 400′′′′ and the electrostatic clamps 204 of the reticle stage 200. In some embodiments, the electrostatic fields can be generated between the RTC reticle 400 and the reticle stage 200 by applying a voltage difference between the RTC reticle 400 and the reticle stage 200 (e.g., by applying a voltage to the clamp electrodes 206 and / or the first front layer 410). In some embodiments, a first electrostatic field can be generated between the first front layer 410 and the electrostatic clamps 204 (e.g., between the burls 208), and a second electrostatic field can be generated between the second front layer 412′, 412″ and the electrostatic clamps 204 (e.g., between the burls 208).

[0102] In step 1608, as shown in the example of FIG. 6C , contaminants (e.g., first particles 210, second particles 212, etc.) present on the electrostatic clamp 204 can be moved (removed) from the reticle stage 200 to the RTC reticle 400, 400′, 400″, 400′′, 400″″, 400″′′, 400″″. In some embodiments, the one or more generated electrostatic fields exert electrostatic forces (e.g., Lorentz forces) and / or van der Waals forces on the contaminants (e.g., first particles 210, second particles 212, etc.), causing the contaminants to move from the reticle stage 200 to the RTC reticle 400. The contaminants (e.g., first particles 210, second particles 212, etc.) contact the first front surface layer 410 (e.g., conductive) and / or the second front surface layer 412′, 412″ (e.g., conductive) and remain on the front surface 402. Additionally, any charge built up on the electrostatic clamp 204 can dissipate when the first front layer 410 (eg, conductive) contacts the electrostatic clamp 204 .

[0103] In step 1610, as shown in the example of Figures 6A-6C, steps 1604, 1606, and 1608 can be repeated (e.g., in multiple cycles) to further transfer (remove) contaminants (e.g., first particles 210, second particles 212, etc.) from the electrostatic clamp 204 to the RTC reticle 400, 400', 400", 400"', 400"", 400""', 400""".

[0104] In some embodiments, step 1604 may include contacting the burls 208 with the first front layer 410 to dissipate charge accumulated on the electrostatic clamp 204. In some embodiments, step 1604 may include contacting the burls 208 with the second front layer 412′, 412″ to remove contaminants (e.g., first particles 210, second particles 212, etc.) on the electrostatic clamp 204. In some embodiments, step 1604 may include contacting the burls 208 with the first front layer 410, 410′ to remove contaminants (e.g., first particles 210, second particles 212, etc.) on the electrostatic clamp 204. For example, as shown in FIGS. 13 and 14 , the burls 208 may be positioned within the first front layer recesses 411 to allow removal of contaminants (e.g., first particles 210) between the burls 208.

[0105] In some embodiments, step 1606 can include generating an electrostatic field between the second front layer 412′, 412″ and the electrostatic clamp 204. For example, a voltage can be applied to the first front layer 410 at the bottom of the grooves 414, 414′, electrically coupled to the second front layer 412′, 412″ above the first front layer 410 inside the grooves 414, 414′.

[0106] Various embodiments of the present system and method are disclosed by the following list of numbered clauses: (Item 1) A cleaning apparatus for cleaning a reticle stage of a lithography apparatus, comprising: a substrate having a front surface and a back surface opposite the front surface; a polyimide layer disposed on the front surface of the substrate and configured to contact the reticle stage to remove particles on the reticle stage; the polyimide layer has radicals therein for imparting electrical conductivity to the polyimide layer for dissipating electrical charges on the reticle stage; Cleaning equipment. (Item 2) The cleaning device according to item 1, wherein the radicals are at least partially formed from broken C-N bonds in imide groups of the polyimide layer. (Item 3) A cleaning device according to any one of the above items, wherein the radicals are at least partially formed from cleaved C-O bonds of polyimide protons. (Item 4) A cleaning apparatus according to any of the above items, wherein the polyimide layer has a lower rigidity than the substrate and a thickness of 8 microns or less to generate an electrostatic field between the polyimide layer and the reticle stage. (Item 5) A chromium nitride layer provided between the polyimide layer and the substrate; 4. The cleaning apparatus of claim 1, further comprising: a positioning device coupled to the backside of the substrate and configured to move the polyimide layer relative to the reticle stage. (Item 6) an illumination system configured to illuminate the patterning device; a projection system configured to project an image of the patterning device onto a patterning substrate; a reticle stage configured to support the patterning device, the reticle stage comprising a chuck and an electrostatic clamp comprising a plurality of burls; a cleaning device for cleaning the reticle stage, the cleaning device comprising: a substrate having a front surface and a back surface opposite the front surface; a polyimide layer disposed on the front surface of the substrate and configured to contact the reticle stage to dissipate charge on the reticle stage and remove particles on the reticle stage; The polyimide layer has radicals therein for providing electrical conductivity to the polyimide layer for dissipating electrical charges on the reticle stage. (Item 7) The lithographic apparatus according to item 6, wherein the polyimide layer has a stiffness lower than a stiffness of the substrate. (Item 8) A method of forming a reticle stage cleaning apparatus for removing particles on a reticle stage in a lithography apparatus, comprising: providing a substrate having a front surface and a back surface opposite the front surface; providing a polyimide layer on the front surface of the substrate; and exposing the polyimide layer to radiation to increase the conductivity of the polyimide layer. (Item 9) The method according to item 8, wherein the irradiation of the polyimide layer forms radicals in the polyimide layer to increase the conductivity of the polyimide layer. (Item 10) The method of item 8 or item 9, wherein the irradiation comprises using one or more of an electron beam, gamma rays, ultraviolet photons, laser radiation, or microwaves. Item 11. The method of any one of items 8 to 10, wherein the polyimide of the polyimide layer is formed by reacting a dianhydride and a diamine in a dipolar aprotic solvent at ambient conditions to obtain a polyamic acid, and then cyclizing the polyamic acid to form the polyimide. (Item 12) The method according to any one of Items 8 to 11, wherein the irradiation is carried out under vacuum conditions. (Item 13) The method according to any one of Items 8 to 11, wherein the irradiation is carried out under atmospheric conditions in the presence of a supplied inert gas. (Item 14) A method according to any one of items 8 to 12, wherein the irradiation is performed inside a lithography apparatus.

[0107] Although specific reference is made herein 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, LCDs, thin-film magnetic heads, etc. Those skilled in the art will understand that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein may be considered synonymous with the more general terms “substrate” or “target portion,” respectively. Substrates referred to herein may be processed, before or after exposure, for example, in 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. Furthermore, a substrate may be processed multiple times, for example to create multi-layer ICs, and thus the term substrate, as used herein, may refer to a substrate already including multiple processed layers.

[0108] Although specific reference has been made above to embodiments being used in the context of optical lithography, it will be understood that embodiments may be used in other applications, for example imprint lithography, and are not limited to optical lithography where the context allows. In imprint lithography, a shape (topography) of a patterning device defines the pattern formed on a substrate. The topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist may be cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is then removed from the resist leaving a pattern behind after the resist is cured.

[0109] It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, and therefore should be interpreted by one skilled in the relevant art in light of the teachings herein.

[0110] As used herein, the term "substrate" refers to a material onto which a layer of material is deposited. In some embodiments, the substrate itself may be patterned, or additional material added onto the substrate may also be patterned or may remain unpatterned.

[0111] The following examples are intended to illustrate, but not limit, embodiments of the present disclosure. Other suitable modifications and adaptations to the variety of conditions and parameters normally encountered in the art and obvious to those skilled in the art are within the spirit and scope of the present disclosure.

[0112] Although specific reference may be made herein to the use of lithographic apparatus and / or systems in the manufacture of ICs, it is expressly understood that such apparatus and / or systems have many other possible applications. For example, they may be used in the manufacture of integrated optical systems, magnetic domain memory guidance and detection patterns, LCD panels, thin film magnetic heads, etc. Those skilled in the art will understand that in the context of these alternative applications, any use of the terms "reticle," "wafer," or "die" herein should be interchangeable with the more general terms "mask," "substrate," and "target portion," respectively.

[0113] While specific embodiments have been described above, it will be understood that embodiments may be practiced other than as described. This description does not limit the scope of the claims.

[0114] It should be noted that the Detailed Description, rather than the Summary and Abstract, is intended to be used to interpret the claims. While the Summary and Abstract may describe one or more exemplary embodiments contemplated by the inventors, they are not exhaustive and are not intended to limit the embodiments and the appended claims in any way.

[0115] The embodiments have been described above using functional blocks that illustrate implementation of specific functions and relationships thereof. The boundaries of these functional blocks are arbitrarily defined in this document for the convenience of explanation. Alternative boundaries may be defined as long as the specific functions and relationships thereof are appropriately performed.

[0116] The foregoing descriptions of specific embodiments fully demonstrate the general nature of the present disclosure, and those skilled in the art can, by applying their knowledge in the art, readily modify and / or adapt such specific embodiments for various applications without undue experimentation and without departing from the general concepts of the present disclosure. 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.

[0117] The breadth and scope of embodiments should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

1. 1. A cleaning apparatus for cleaning a reticle stage of a lithographic apparatus, comprising: a substrate having a front surface and a back surface opposite the front surface; a polyimide layer disposed on the front surface of the substrate and configured to contact the reticle stage to remove particles on the reticle stage; the polyimide layer has radicals therein for imparting electrical conductivity to the polyimide layer for dissipating electrical charges on the reticle stage; Cleaning equipment.

2. the radicals are formed at least in part from broken C—N bonds within imide groups of the polyimide layer; The cleaning device according to claim 1 .

3. the radicals are formed at least in part from cleaved C—O bonds of polyimide protons; The cleaning device according to claim 1 .

4. the polyimide layer has a lower stiffness than the substrate and a thickness of 8 microns or less for generating an electrostatic field between the polyimide layer and the reticle stage. The cleaning device according to claim 1 .

5. a chromium nitride layer disposed between the polyimide layer and the substrate; a positioning device coupled to the backside of the substrate and configured to move the polyimide layer relative to the reticle stage. The cleaning device according to claim 1 .

6. an illumination system configured to illuminate the patterning device; a projection system configured to project an image of the patterning device onto a patterning substrate; a reticle stage configured to support the patterning device, the reticle stage comprising a chuck and an electrostatic clamp comprising a plurality of burls; a cleaning device for cleaning the reticle stage, The cleaning device a substrate having a front surface and a back surface opposite the front surface; a polyimide layer disposed on the front surface of the substrate and configured to contact the reticle stage to dissipate charge on the reticle stage and remove particles on the reticle stage; the polyimide layer has radicals therein for imparting electrical conductivity to the polyimide layer for dissipating electrical charges on the reticle stage; Lithography equipment.

7. the polyimide layer has a rigidity lower than that of the substrate; The lithographic apparatus of claim 6.

8. 1. A method of forming a reticle stage cleaning apparatus for removing particles on a reticle stage in a lithographic apparatus, comprising: providing a substrate having a front surface and a back surface opposite the front surface; providing a polyimide layer on the front surface of the substrate; and exposing the polyimide layer to radiation to increase the conductivity of the polyimide layer.

9. the irradiation of the polyimide layer forms radicals in the polyimide layer, increasing the conductivity of the polyimide layer; The method of claim 8.

10. the irradiating comprises using one or more of an electron beam, gamma rays, ultraviolet photons, laser radiation, or microwaves; The method of claim 8.

11. the polyimide of the polyimide layer is formed by reacting a dianhydride and a diamine in a dipolar aprotic solvent at ambient conditions to form a polyamic acid, and then cyclizing the polyamic acid to form the polyimide; The method of claim 8.

12. The irradiation is carried out under vacuum conditions. The method of claim 8.

13. The irradiation is carried out under atmospheric conditions in the presence of a supplied inert gas; The method of claim 8.

14. the irradiation is performed inside a lithographic apparatus. The method of claim 8.

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