Electrostatic clamp with dissimilar conductive coating

Abstract

A lithography system includes an electrostatic clamp for holding substrates during operation of the lithography system. The electrostatic clamp includes an electrode layer positioned between two dielectric plates. A channel extends through the two dielectric plates and the electrode layer. A conductive coating covers at least a region of the electrode layer that is exposed to the channel. The conductive coating and the electrode are fabricated from different materials that have different etch rates in an etchant, such that the etch rate of the conductive coating in the etchant is faster than the etch rate of the electrode layer in the etchant.

Description

ELECTROSTATIC CLAMP WITH DISSIMILAR CONDUCTIVE COATINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the priority benefit of U.S. Provisional Patent Application Number 63 / 779,705, filed March 28, 2025, which is incorporated by reference herein in its entirety.FIELD

[0002] The present application relates to systems and methods for electrostatic clamping, for example, electrostatic clamping of reticles and substrates in lithography apparatuses and systems.BACKGROUND

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which can be a mask or a reticle, can be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g., comprising part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiationsensitive material (photoresist or simply “resist”) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatuses include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called 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 target portions parallel or anti-parallel to this scanning direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0004] During patterning, a reticle and / or substrate must be held at a precise location. This may be accomplished through use of an electrostatic clamp. Electrostatic clamps may generate a Coulomb force that attracts and affixes and object in place. In many electrostatic clamp designs, the Coulomb force is generated by applying a voltage to an electrode sandwiched between two dielectric layers. Voltage may be supplied to the electrode via an electrical connection that extends through at least one of the dielectric layers.

[0005] Due to manufacturing errors and / or breakdown during typical use, portions of an electrostatic clamp, including the electrical connection, may need to be refurbished. In current electrostatic clamp designs it is difficult to refurbish the electrical connection without damaging portions of the electrode and / or dielectric layers.SUMMARY

[0006] Accordingly, it is desirable to design a clamp for a lithography apparatus that may be better repaired, reworked, or refurbished.

[0007] In some aspects, a lithography apparatus includes an electrostatic clamp. The electrostatic clamp includes an electrode layer positioned between two dielectric plates. A channel extends through the two dielectric plates and the electrode layer. A conductive coating covers at least a region of the electrode layer that is exposed to the channel. The electrode layer and the conductive coating include different materials with different etching rates in an etchant. The etch rate of conductive coating in the etchant is faster than the etch rate of the electrode layer in the etchant.

[0008] In some aspects, a method for refurbishing the electrostatic clamp described above includes exposing the conductive coating. This may be accomplished, for example, by removing a cap from the surface of one of the dielectric plates and / or removing conductive epoxy from a portion of the channel. After the conductive coating is exposed, the method includes etching the conductive coating using an etchant that etches the conductive coating material faster than the electrode layer material.

[0009] Further features of various aspects of the present disclosure are described in detail below with reference to the accompanying drawings. It is noted that the present disclosure is not limited to the specific aspects described herein. Such aspects are presented herein for illustrative purposes only. Additional aspects will be apparent to those skilled in the relevant art(s) based on the teachings contained herein.BRIEF DESCRIPTION OF THE DRAWINGS / FIGURES

[0010] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art(s) to make and use aspects described herein.

[0011] FIG. 1A shows a reflective lithographic apparatus, according to some aspects.

[0012] FIG. IB shows a transmissive lithographic apparatus, according to some aspects.

[0013] FIGS. 2A and 2B show more details of a reflective lithographic apparatus, according to some aspects.

[0014] FIG. 3 shows an example lithographic cell, according to some aspects.

[0015] FIGS. 4 and 5 show an example reticle stage, according to some aspects.

[0016] FIGS. 6 and 7 show example electrostatic clamps, according to some aspects.

[0017] FIG. 8 shows a method, according to some aspects.

[0018] The features of the present disclosure 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 indicateidentical, functionally similar, and / or structurally similar elements. Additionally, generally, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.DETAILED DESCRIPTION

[0019] The aspects described herein, and references in the specification to “one aspect,” “an aspect,” “an exemplary aspect,” “an example aspect,” etc., indicate that the aspects described can include a particular feature, structure, or characteristic, but every aspect may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same aspect. Further, when a particular feature, structure, or characteristic is described in connection with an aspect, it is understood that it is within the knowledge of those skilled in the art to effect such feature, structure, or characteristic in connection with other aspects whether or not explicitly described.

[0020] Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “on,” “upper,” and the like, can be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein can likewise be interpreted accordingly.

[0021] The terms “about,” “approximately,” or the like as used herein indicate the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the terms “about,” “approximately,” or the like can indicate a value of a given quantity that varies within, for example, 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

[0022] Before describing such aspects in more detail, however, it is instructive to present an example environment in which aspects of the present disclosure can be implemented.

[0023] Example Lithographic Systems

[0024] FIGS. 1A and IB show schematic illustrations of a lithographic apparatus 100 and a lithographic apparatus 100’, respectively, in which aspects of the present disclosure can be implemented. Lithographic apparatus 100 and lithographic apparatus 100’ can each include the following: an illumination system (illuminator) IL configured to condition a radiation beam B (for example, deep ultra violet or extreme ultra violet radiation); a support structure (for example, a mask table) MT configured to support a patterning device (for example, a mask, a reticle, or a dynamic patterning device) MA and connected to a first positioner PM configured to accurately position patterning device MA; and, a substrate table (for example, a wafer table) WT configured to hold a substrate (for example, a resist coated wafer) W and connected to a second positioner PW configured to accurately position substrate W. Lithographic apparatus 100 and 100’ also comprises a projection system PS configured to project a pattern imparted to radiation beam B by patterning device MA ontoa target portion (for example, comprising one or more dies) C of substrate W. In lithographic apparatus 100, patterning device MA and the projection system PS are reflective. In lithographic apparatus 100’, the patterning device MA and projection system PS are transmissive.

[0025] Illumination system IL can comprise various types of optical components, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation beam B. Illumination system IL can also comprise a sensor ES that provides a measurement of, for example, one or more of energy per pulse, photon energy, intensity, average power, and the like. Illumination system IL can comprise a measurement sensor MS for measuring a movement of radiation beam B and a uniformity compensator UC that allow an illumination slit uniformity to be controlled. Measurement sensor MS can also be disposed at other locations. For example, measurement sensor MS can be on or near substrate table WT.

[0026] The support structure MT can support patterning device MA in a manner that depends on the orientation of the patterning device MA with respect to a reference frame, the design of at least one of the lithographic apparatus 100 and 100’, and other conditions, such as whether the patterning device MA is held in a vacuum environment. The support structure MT can implement mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. Support structure MT can be a frame or a table. Support structure MT can be fixed or movable. By using sensors, support structure MT can ensure that patterning device MA is at a desired position, for example, with respect to the projection system PS.

[0027] The term “patterning device” can 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 target portion C of substrate W. The pattern imparted to radiation beam B can correspond to a particular functional layer in a device being created in target portion C to form an integrated circuit.

[0028] Patterning device MA can be reflective (as in lithographic apparatus 100 of FIG. 1A), or transmissive (as in lithographic apparatus 100’ of FIG. IB). Examples of patterning devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks can include different mask types, such as binary, alternating phase shift, or 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 can impart a pattern in radiation beam B, which is reflected by a matrix of small mirrors.

[0029] The terms “inspection apparatus,” “metrology system,” or the like may be used herein to refer to, e.g., a device or system used for measuring a property of a structure (e.g., overlay error, critical dimension parameters) or used in a lithographic apparatus to inspect an alignment of a wafer (e.g., alignment apparatus).

[0030] The term “projection system” can be used herein to refer to any type 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 on the substrate W or the use of a vacuum. Atmospheric gas can absorb EUV or electrons used for exposing a substrate. Therefore, a vacuum environment can be used for EUV or electron beam radiation. A vacuum environment can be provided to the whole beam path with the aid of a vacuum wall and vacuum pumps.

[0031] Lithographic apparatus 100 and / or lithographic apparatus 100’ can be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such “multiple stage” machines, 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. In some situations, the additional table may be different from substrate table WT.

[0032] The lithographic apparatus can also be of a type in which at least a portion of the substrate can 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 can also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques can increase 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. For example, a liquid can be located between the projection system and the substrate during exposure.

[0033] Referring to FIGS. 1A and IB, illuminator IL can receive a radiation beam from a radiation source SO. Source SO and lithographic apparatus 100 or 100’ can be separate physical entities, for example, in arrangements where the source SO is an excimer laser. In such cases, source SO is not considered to be part of lithographic apparatus 100 or 100’ and radiation beam B can pass from source SO to illuminator IL with the aid of a beam delivery system BD (in FIG. IB), which can include, for example, suitable directing mirrors and / or a beam expander. In other cases, source SO can be an integral part of the lithographic apparatus 100 or 100’, for example, in arrangements where the source SO is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD, if required, may be referred to as a radiation system.

[0034] The illuminator IL may include an adjuster AD (in FIG. IB) for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and / or inner radial extent (commonly referred to as “o-outer” and “o-inner,” respectively) of the intensity distribution in a pupil plane of the illuminator may be adjusted. In addition, the illuminator IL may comprise various other components (in FIG. IB), such as an integrator IN and a condenser CO. The illuminator IL may be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross section.

[0035] Referring to FIG. 1A, the radiation beam B is incident on the patterning device (for example, mask) MA, which is held on the support structure (for example, mask table) MT, and is patterned by the patterning device MA. In lithographic apparatus 100, the radiation beam B is reflected from thepaterning device (for example, mask) MA. After being reflected from the paterning device (for example, 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 (for example, an interferometric device, linear encoder, or capacitive sensor), the substrate table WT may be moved accurately (for example, 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 may be used to accurately position the paterning device (for example, mask) MA with respect to the path of the radiation beam B. Paterning device (for example, mask) MA and substrate W may be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2.

[0036] Referring to FIG. IB, the radiation beam B is incident on the paterning device (for example, mask MA), which is held on the support structure (for example, mask table MT), and is paterned by the paterning 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. The projection system has a pupil conjugate PPU to an illumination system pupil IPU. Portions of radiation emanate from the intensity distribution at the illumination system pupil IPU and traverse a mask patern without being affected by diffraction at the mask patern and create an image of the intensity distribution at the illumination system pupil IPU.

[0037] The projection system PS projects an image of the mask patern MP, where the image is formed by diffracted beams produced from the mark patern MP by radiation from the intensity distribution, onto a photoresist layer coated on the substrate W. For example, the mask patern MP may include an array of lines and spaces. A diffraction of radiation at the array and different from zeroth order diffraction generates diverted diffracted beams with a change of direction in a direction perpendicular to the lines. Undiffracted beams (i.e., so-called zeroth order diffracted beams) traverse the patern without any change in propagation direction. The zeroth order diffracted beams traverse an upper lens or upper lens group of the projection system PS, upstream of the pupil conjugate PPU of the projection system PS, to reach the pupil conjugate PPU. The portion of the intensity distribution in the plane of the pupil conjugate PPU and associated with the zeroth order diffracted beams is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IU. The aperture device PD, for example, is disposed at or substantially at a plane that includes the pupil conjugate PPU of the projection system PS.

[0038] The projection system PS is arranged to capture, by means of a lens or lens group U, not only the zeroth order diffracted beams, but also first-order or first- and higher-order diffracted beams (not shown). In some embodiments, dipole illumination for imaging line paterns extending in a direction perpendicular to a line may be used to utilize the resolution enhancement effect of dipole illumination. For example, first-order diffracted beams interfere with corresponding zeroth-order diffracted beams at the level of the wafer W to create an image of the line patern MP at highest possible resolution and process window (i.e., usable depth of focus in combination with tolerable exposure dose deviations). Insome embodiments, astigmatism aberration may be reduced by providing radiation poles (not shown) in opposite quadrants of the illumination system pupil IPU. Further, in some embodiments, astigmatism aberration may be reduced by blocking the zeroth order beams in the pupil conjugate PPU of the projection system associated with radiation poles in opposite quadrants. This is described in more detail in U.S. Pat. No. 7,511,799, the contents of which are incorporated by reference herein in its entirety.

[0039] With the aid of the second positioner PW and position sensor IFD (for example, an interferometric device, linear encoder, or capacitive sensor), the substrate table WT may be moved accurately (for example, 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. IB) may be used to accurately position the mask MA with respect to the path of the radiation beam B (for example, after mechanical retrieval from a mask library or during a scan).

[0040] In general, movement of the mask table MT may 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 may 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 may be connected to a short-stroke actuator only or may be fixed. Mask MA and substrate W may be aligned using mask alignment marks Ml, M2, and substrate alignment marks Pl, P2. Although the substrate alignment marks (as illustrated) occupy dedicated target portions, they may 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 may be located between the dies.

[0041] Mask table MT and patterning device MA may be in a vacuum chamber V, where an in-vacuum robot IVR may be used to move patterning devices such as a mask in and out of vacuum chamber. Alternatively, in arrangements where mask table MT and patterning device MA are outside of the vacuum chamber, an out-of-vacuum robot may be used for various transportation operations, similar to the in-vacuum robot IVR. Both the in-vacuum and out-of-vacuum robots need to be calibrated for a smooth transfer of any payload (e.g., mask) to a fixed kinematic mount of a transfer station.

[0042] The lithographic apparatus 100 and 100’ can be used in at least one of the following modes:

[0043] 1. In step mode, support structure MT and substrate table WT can be kept essentially stationary, while an entire pattern imparted to radiation beam B is projected onto a target portion C at one time (e.g., a single static exposure). Substrate table WT can then be shifted in the X and / or Y direction so that a different target portion C can be exposed.

[0044] 2. In scan mode, support structure MT and substrate table WT can be scanned synchronously while a pattern imparted to radiation beam B is projected onto a target portion C (e.g., a single dynamic exposure). The velocity and direction of substrate table WT relative to support structure MT can be determined by (de-)magnification and image reversal characteristics of projection system PS.

[0045] 3. In another mode, support structure MT can be kept substantially stationary holding a programmable patterning device, and substrate table WT can be moved or scarmed while a pattern imparted to radiation beam B is projected onto a target portion C. A pulsed radiation source SO can be employed and the programmable patterning device is updated after each movement of 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.

[0046] Combinations and / or variations on the described modes of use or entirely different modes of use can also be employed.

[0047] 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, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0048] FIG. 2A shows different view of lithographic apparatus 100, including source SO (e.g., source collector apparatus), illumination system IL, and projection system PS, according to some aspects. Source SO is constructed and arranged such that a vacuum environment can be maintained in an enclosing structure 220 of source SO. An EUV radiation emitting plasma 210 can be formed by a discharge-generated plasma source. In some aspects, a plasma of excited tin (Sn) (e.g., excited via a laser) is used to produce EUV radiation.

[0049] The radiation emitted by the EUV radiation emitting plasma 210 can be passed from a source chamber 211 into a collector chamber 212 via an optional gas barrier or contaminant trap 230 (in some cases also referred to as contaminant barrier or foil trap), which is positioned in or behind an opening in source chamber 211. Contaminant trap 230 can comprise a channel structure. Contamination trap 230 can also comprise a gas barrier and / or a channel structure.

[0050] In some aspects, collector chamber 212 can comprise a radiation collector CO. Radiation collector CO can be a so-called grazing incidence collector. Radiation collector CO can comprise an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation that traverses radiation collector CO can be reflected off a grating spectral filter 240 to be focused in a virtual source point INTF. Virtual source point INTF can be referred to as the intermediate focus. Source collector apparatus can be arranged such that the intermediate focus INTF is located at or near an opening 219 of enclosing structure 220. The virtual source point INTF can be an image of the EUV radiation emitting plasma 210. Grating spectral filter 240 can be used for suppressing infrared (IR) radiation.

[0051] Subsequently, the radiation traverses the illumination system IL. Illumination system IL can include a faceted field mirror device 222 and a faceted pupil mirror device 224 arranged to provide a desired angular distribution of radiation beam 221, at patterning device MA, as well as a desired uniformity of radiation intensity at patterning device MA. Upon reflection of beam of radiation 221 atpaterning device MA, held by support structure MT, a paterned beam 226 is formed and the paterned beam 226 is imaged by projection system PS via reflective elements 228, 229 onto substrate W held by the wafer stage or substrate table WT. In some aspects, other configurations of mirrors and / or optical devices can be used to direct radiation beam 221 to paterning device MA.

[0052] More elements than shown can generally be present in illumination system IL and projection system PS. Grating spectral filter 240 can optionally be present, depending upon the type of lithographic apparatus. Further, there can be more mirrors present than those shown in the FIG. 2A, for example there can be one to six additional reflective elements present in the projection system PS than shown in FIG. 2A.

[0053] In some aspects, uniformity compensator UC, sensor ES, and / or measurement sensor MS shown in FIGS. 2A and 2B can be as described above in reference to FIG. 1A.

[0054] Collector CO, as illustrated in FIG. 2A, is depicted as an example of a nested collector with grazing incidence reflectors 253, 254, and 255 (or collector mirror). Grazing incidence reflectors 253, 254, and 255 can be disposed axially symmetric around an optical axis O. A collector optic of this type can be used in combination with a discharge-generated plasma source, often called a DPP source.

[0055] FIG. 2B shows a portion of lithographic apparatus 100 (e.g., FIG. 1A), but with alternative collection optics in source SO, according to some aspects. It should be appreciated that structures shown in FIG. 2A that do not appear in FIG. 2B (for drawing clarity) can still be included in aspects referring to FIG. 2B. Elements in FIG. 2B having the same reference numbers as those in FIG. 2A have the same or substantially similar structures and functions as described in reference to FIG. 2A. In some aspects, the lithographic apparatus 100 can be used, for example, to expose a substrate W such as a resist-coated wafer with a paterned beam of EUV illumination. In FIG. 2B, illumination system IL and projection system PS are represented combined as an exposure device 256 (e.g., an integrated circuit lithography tool such as a stepper, scanner, step and scan system, direct write system, device using a contact and / or proximity mask, etc.) that uses EUV light from source SO. Lithographic apparatus 100 can also comprise collector 258 that reflects EUV light from the EUV radiation emiting plasma 210 along a path into the exposure device 256 to irradiate substrate W. Collector 258 can comprise a near-normal incidence collector mirror having a reflective surface in the form of a prolate spheroid (e.g., an ellipse rotated about its major axis). The prolate spheroid structure can have a graded multi-layer coating with alternating layers of Molybdenum and Silicon, and in some cases, one or more high temperature diffusion barrier layers, smoothing layers, capping layers and / or etch stop layers.

[0056] Example Lithographic Cell

[0057] FIG. 3 shows a lithographic cell 300, also sometimes referred to a lithocell or cluster, according to some aspects. Lithographic apparatus 100 or 100’ (FIGS. 1A and IB) can form part of lithographic cell 300. Lithographic cell 300 can also comprise one or more apparatuses to perform pre-exposure and post-exposure processes on a substrate. These can include spin coaters SC to deposit resist layers, developers DE to develop exposed resist, chill plates CH, and bake plates BK. A substrate handler, orrobot, RO picks up substrates from input / output ports I / Ol, I / O2, moves them between the different process apparatuses and delivers them to the loading bay LB of lithographic apparatus 100 or 100’. These devices, which are often collectively referred to as the track, are under the control of a track control unit TCU, which is itself controlled by a supervisory control system SCS, which also controls the lithographic apparatus via lithography control unit LACU. Thus, the different apparatuses can be operated to maximize throughput and processing efficiency.

[0058] Example Reticle Stage

[0059] FIGS. 4 and 5 show schematic illustrations of an example reticle stage 400, according to some aspects. Reticle stage 400 may include top stage surface 402, bottom stage surface 404, side stage surfaces 406, and clamp 500. In some aspects, reticle stage 400 with clamp 500 is implemented in lithographic apparatus 100 or 100’. For example, reticle stage 400 may be incorporated within mask table MT in lithographic apparatus 100 or 100’. In some aspects, clamp 500 can be disposed on top stage surface 402. For example, as shown in FIG. 4, clamp 500 can be disposed at a center of top stage surface 402 with clamp front side 502 facing perpendicularly away from top stage surface 402.

[0060] In some lithographic apparatuses, for example, lithographic apparatus LA, a reticle stage 400 with a clamp 500 can be used to hold and position a reticle for scanning or patterning operations. In one example, the reticle stage 400 can require powerful drives, large balance masses, and heavy frames to support it. In one example, the reticle stage 400 can have a large inertia and can weigh over 500 kg to propel and position a reticle weighing about 0.5 kg. To accomplish reciprocating motions of the reticle 408, which are typically found in lithographic scanning or patterning operations, accelerating and decelerating forces may be provided by linear motors that drive the reticle stage 400.

[0061] In some embodiments, as shown in FIGS. 4 and 5, reticle stage 400 can include first encoder 412 and second encoder 414 for positioning operations. For example, first and second encoders 412, 414 may be interferometers. First encoder 412 may be attached along a first direction, for example, a transverse direction (i.e., X-direction) of reticle stage 400. And second encoder 414 may be attached along a second direction, for example, a longitudinal direction (i.e., Y-direction) of reticle stage 400. In some aspects, as shown in FIGS. 4 and 5, first encoder 412 may be orthogonal to second encoder 414.

[0062] As shown in FIGS. 4 and 5, reticle stage 400 may include clamp 500. Clamp 500 is configured to hold a reticle in a fixed plane on reticle stage 400. Clamp 500 includes clamp front side 502 and can be disposed on top stage surface 402. In some aspects, clamp 500 can use mechanical, vacuum, electrostatic, or other suitable clamping techniques to hold and secure an object. In some embodiments, clamp 500 can be an electrostatic clamp, which can be configured to electrostatically clamp (i.e., hold) an object, for example, a reticle in a vacuum environment. Due to the requirement to perform EUV in a vacuum environment, vacuum clamps cannot be used to clamp a mask or reticle and instead electrostatic clamps can be used. For example, clamp 500 can include an electrode, sandwiched between two dielectric layers. In use, a voltage can be applied to clamp 500, for example, several kV (e.g., high-voltage). The voltage generates an electric field that leads to a Coulomb force (e.g., attractive forcebetween electrically opposite charged particles), that attracts an object to clamp 500 and holds the object in place. In some aspects, clamp 500 can be arigid material, for example, a metal, a dielectric, a ceramic, or a combination thereof. As understood by a person of ordinary skill in the art, clamp 500 may similarly be integrated into a wafer table, such as wafer table WT.

[0063] Example Electrostatic Clamp

[0064] FIG. 6 shows a side view of a schematic of an electrostatic clamp 600, according to some aspects. Specifically, FIG. 6 may show a region of electrostatic clamp 600 which includes an electrical feedthrough. As described below, the electrical feedthrough may house components that provide an electrical connection to an electrode.

[0065] Electrostatic clamp 600 may include a first (e.g., top) dielectric plate 602, a second (e.g., bottom) dielectric plate 604, and an electrode 606. Electrode 606 may include a thin layer of conductive material deposited on one or both of first dielectric plate 602 and second dielectric plate 604. First dielectric plate 602 and second dielectric plate 604 may be bonded such that electrode 606 is sandwiched between the first and second dielectric plates. In some aspects, a channel 608 extends through first dielectric plate 602, electrode 606, and second dielectric plate 604. Channel 608 may be fabricated, for example, by drilling a hole through first dielectric plate 602, electrode 606, and second dielectric plate 604 using a computer numerical control (CNC) milling process or the like. In some aspects, a first (e.g., top) portion of channel 608 may be chamfered.

[0066] Channel 608 may include one or more conductive components that provide an electrical connection to electrode 606. The one or more conductive components may, for example, connect electrode 606 to a power supply (not shown). In some aspects, the one or more conductive components may include a conductive coating 610, a conductive pin 612, and a conductive adhesive 614. Conductive coating 610 may establish an electrical connection with an exposed portion of electrode 606 along an edge of channel 608. For example, in FIG. 6, conductive coating 610 includes a thin layer of a conductive material that is deposited along a chamfered portion of the channel. In some aspects, conductive coating 610 may extend out of channel 608 and onto a first (e.g., top) surface of first dielectric plate 602. This configuration allows for grounding at the surface of first dielectric plate 602.

[0067] Conductive pin 612 may extend through second dielectric plate 604 towards electrode 606 inside channel 608. In some aspects, conductive pin 612 electrically connects with electrical components (e.g., additional conductive pins) within a wafer or mask table, such as wafer table WT or mask table MT. In an alternative aspect (not shown), conductive pin 612 may be replaced with other conductive pathways. For example, conductive pin 612 may be replaced with a conductive coating applied along portions of second dielectric plate 604 that are exposed to channel 608.

[0068] Conductive adhesive 614 may be fabricated by adding conductive particles (e.g., silver, carbon graphite, etc.) to an adhesive. In some aspects, conductive adhesive 614 may fill at least some empty portions of channel 608. For example, conductive adhesive 614 may hold conductive pin 612 in place within channel 608. Additionally, conductive adhesive 614 may provide a conductive pathway betweenconductive pin 612 and conductive coating 610. In some aspects, conductive adhesive 614 may fill all of channel 608. A cap 616 may provide electrical isolation to conductive elements within channel 608. In some aspects, cap 616 may be bonded via an adhesive layer 617. Adhesive layer 617 may be disposed between conductive adhesive 614 and cap 616, between conductive coating 610 and cap 616, and / or between first dielectric layer 602 and cap 616. Adhesive layer 617 may comprise the same material as conductive adhesive 614. Cap 616 may include athin layer (e.g., 100-500 micrometers) of an insulating material, such as glass or the like.

[0069] In some aspects, electrostatic clamp 600 may include multiple channels 608. For example, electrostatic clamp 600 may have six channels that provide high voltage and / or grounding to different regions of electrostatic clamp 600.

[0070] FIG. 7 shows an example of an electrostatic clamp 700, according to some aspects. Electrostatic clamp 700 may include a first (e.g., top) dielectric plate 702, a second (e.g., bottom) dielectric plate 704, and an electrode 706. Electrode 706 may include a thin conductive layer positioned between first dielectric plate 702 and second dielectric plate 704. A channel 708 may extend through first dielectric plate 702, second dielectric plate 704, and electrode 706. Channel 708 may be fabricated, for example, by etching first dielectric plate 702 until electrode 706 is exposed. Then, a hole may be drilled through electrode 706 and second dielectric plate 704. When channel 708 is fabricated in this manner, at least a portion of a first (e.g., top) surface of electrode 706 is exposed within channel 708.

[0071] In some aspects, channel 708 includes one or more conductive components that provide an electrical connection to electrode 706. The conductive components may include, a conductive coating 710, a conductive pin 712, and a conductive adhesive 714. The conductive coating 710 may, as shown in FIG. 7, cover a portion of the first (e.g., top) surface of electrode 706. In some aspects, conductive coating 710 extends along sides of and onto a first (e.g., top) surface of first dielectric plate 702. This configuration may allow for grounding at the first surface of first dielectric plate 702.

[0072] Conductive pin 712 may extend, within channel 708, through second dielectric plate 704 towards electrode 706. In some aspects, conductive pin 712 electrically connects with electrical elements (e.g., another conductive pin) within a wafer or mask table, such as wafer table WT or mask table MT. In an alternative aspect (not shown), conductive pin 712 may be replaced with other conductive pathways. For example, conductive pin 712 may be replaced with another conductive coating applied along edges of second dielectric layer 704 that are exposed to channel 708.

[0073] Conductive adhesive 714 may fill at least some empty portions of channel 708. For example, conductive adhesive 714 may hold conductive pin 712 in place and provide a conductive pathway between conductive pin 712 and conductive coating 710. In some aspects, conductive adhesive 714 fills all of channel 708. A cap 716 may provide electrical isolation to conductive elements within channel 708. In some aspects, cap 716 may be bonded via an adhesive layer 717. Adhesive layer 717 may be disposed between conductive adhesive 714 and cap 716, between conductive coating 710 and cap 716, and / or between first dielectric layer 702 and cap 716. Adhesive layer 717 may comprise the samematerial as conductive adhesive 714. Cap 716 may include a thin (e.g., about 100-500 micrometers) plate of electrically insulating material, such as glass or the like.

[0074] In some aspects, electrostatic clamp 700 may include multiple channels 708. For example, electrostatic clamp 700 may have six channels that provide high voltage and / or grounding to different regions of electrostatic clamp 700.

[0075] Electrostatic clamps, such as electrostatic clamps 600 and 700, may need their electrical connections repaired or remade during their manufacturing process or during refurbishment. This typically includes removing at least conductive coating 610 / 710. Conductive coating 610 / 710 is typically removed via chemical etching, or the like. When conductive coating 610 / 710 and electrode 606 / 706 have similar etch rates in an etchant, portions of electrode 606 / 706 may also be removed. For example, etching may remove electrode material from regions 618 and 718 of electrostatic clamps 600 and 700, respectively. Etching of electrode 606 / 706 may make it more difficult to repair or refurbish electrostatic clamp 600 / 700. For example, when region 618 is etched, channel 608 may need to be remilled to allow a new conductive coating to contact the electrode. However, electrostatic clamp 600 may not have enough tolerance for re-milling, and, furthermore, re-milling may introduce contaminants, damage, and / or increase processing costs of electrostatic clamp 600. When region 718 of electrode 706 is etched, portions of electrode 706 may need to be redeposited. Redepositing portions of electrode 706 introduces the risk of electrical discontinuity between old and new portions of the electrode.

[0076] To remedy these issues, in some aspects conductive coating 610 / 710 and electrode 606 / 706 may include dissimilar materials with different etch rates in an etchant. In some aspects, conductive coating 610 / 710 may have an etching rate in an etchant that is, for example, greater than about 20 times, greater than about 10 times, greater than about 5 times or greater than about 2 times the etching rate to electrode 606 / 706 in the etchant. The etchant may also be chosen to have limited effect on first dielectric plate 602 / 702 and second dielectric plate 604 / 704 (e.g., glass, ceramic, or the like).

[0077] Table 1 below shows examples of electrode materials, conductive coating materials, and etchants. In the examples shown in Table 1, the etching time required to remove coating materials may be between, e.g., approximately 1 minute and 60 minutes. The etching time may depend, for example, on the thickness of the conductive coating, the temperature, and the concentration of the etchant. For example, the thickness of the conductive coating may be about 1-10,000 nanometers (nm) or about 10-1,000 nm. The examples shown in Table 1 are non-limiting. Different combinations of electrode materials, conductive coating materials, and etchants may be envisaged based on the knowledge of a person of ordinary skill in the art.Table 1

[0078] In example 1, an electrode material includes chromium (Cr) and a coating material includes a titanium tungsten alloy (TiW). The titanium tungsten alloy may be between about 5-20% wt. titanium and 80-95% wt. tungsten. The etchant may include one of: about 30% wt. hydrogen peroxide (H2O2) and 70% wt. water, Transene TI -TUNGSTEN ETCHANT TiW-30, Microchemicals TiW Etch 100, and Microchemicals TiW Etch 200. Transene “TI-TUNGSTEN ETCHANT TiW-30” may include about -29-32 % wt. hydrogen peroxide (H2O2), <0.1 % wt. Triphenyl -2H-tetrazolium chloride (TTC), <0.1 % wt. surfactant, and -68-71% wt. water.

[0079] In example 2, an electrode material is aluminum and a coating material is one of: titanium (Ti), a titanium tungsten alloy (TiW), and titanium nitride (TiN) . The titanium tungsten alloy may be between about 5-20% wt. titanium and 80-95% wt. tungsten. An etchant may include about 94% wt. of 30%hydrogen peroxide (H2O2) and 6 % wt. TBR19, where TBR19 is a “TechniEtch TBR19 Concentrate” manufactured by Microchemicals.

[0080] In example 3, the electrode material is aluminum, the coating material is chromium. The etchant may include one of: Microchemicals Cr etch 210 and Transene Chromium etchant 1020.

[0081] In example 4, the electrode material is titanium, the coating material is a titanium tungsten alloy, and the etchant is one of 30% wt. H2O2 / 70 % wt. H2O and Microchemicals Cu etch 100. The titanium tungsten alloy may be between about 5-20% wt. titanium and 80-95% wt. tungsten.

[0082] In example 5, the electrode material is chromium, the coating material is tungsten, and the etchant is about 30% wt. hydrogen peroxide (H2O2) and 70% wt. water.

[0083] In example 6, the electrode material is silicon, the coating material is titanium, and the etchant is about -20-30% wt. hydrochloric acid (HC1) and -70-80% wt. water.

[0084] In example 7, the electrode material is silicon, the coating material is chromium, and the etchant is about -4-6% wt. nitric acid, -10-20% wt. ceric ammonium nitrate (NH^CefNCh^, and -74-86% wt. water.

[0085] In example 8, the electrode material is one of: titanium, silicon, and aluminum, the coating material is chromium, and the etchant is about 22% wt. ceric ammonium nitrate (NH^CefNCh^, 8% wt. acetic acid (CH3COOH), and 30% wt. water.

[0086] In example 9, the electrode material is tantalum, the coating material is chromium, and the etchant is about 9% wt. (NH^CefNCh^, 6% wt. HCIO4, and 85% wt. water.

[0087] In example 10, the electrode material is one of: chromium, tantalum, molybdenum, titanium tungsten, and niobium. The coating material is one of: titanium, aluminum, and nickel. The etchant is about 50: 1 96% H2SO4 : 30%H2C>2 (a piranha composition).

[0088] In example 11, the electrode material is chromium, the coating material is one of titanium or titanium nitride, and the etchant is one of: SF6, SFe / Ar, CF4, CF4 / Ar, CHF3, CHFJAr. CI2, and CF / Ar. The etchant may be in gaseous form. The exact gas mixture compositions may be determined experimentally, and may depend on an etching process method, etching equipment, and other process parameters. Etching process methods may include, reactive ion etching (RIE), inductively coupled plasma reactive ion etching (ICP-RIE), and the like.

[0089] FIG. 8 shows a flowchart of a process 800, according to some aspects. Process 800 may describe a method for refurbishing electrical connections within an electrostatic clamp. It is to be appreciated that not all steps of process 800 may be needed to perform the disclosure provided herein. Further, some of the steps may be performed simultaneously, or in a different order than described for FIG. 8, as will be understood by a person of ordinary skill in the art. Process 800 shall be described with reference to FIGS. 1-7. However, process 800 is not limited to those example aspects.

[0090] At 802, a conductive coating (e.g., conductive coating 610 / 710) within a channel of (e.g., channel 608 / 708) electrostatic clamp is exposed. In some aspects, exposing the conductive coating includes removing a protective cap (e.g., cap 616 / 716) and at least a portion of a conductive epoxy (e.g.,conductive epoxy 614.714) within the channel. The conductive epoxy may be removed using common techniques, such as solvents, heat, scraping, and the like.

[0091] At 804, the conductive coating is removed. The conductive coating may be removed, for example, via etching. When the electrode and the conductive coating comprise different materials, a chosen etchant may selectively etch the conductive coating while leaving the electrode (and dielectric layers) largely intact. For example, the etchant may etch the conductive coating over about 20 times faster, over about 10 times faster, over about 5 times faster, or over about 2 times faster than the electrode.

[0092] At 806, electrical connections within the electrostatic clamp are reassembled. For example, a new conductive coating may be deposited to cover at least a portion of the electrode that is exposed to the channel. The conductive coating may be deposited via sputtering or the like. Reassembly may also include adding conductive epoxy to portions of the channel and covering the electrical elements within the channel with a protective cap.

[0093] Various example embodiments of the present disclosure include the following numbered clauses:1. A lithography apparatus, comprising:an electrostatic clamp comprising:an electrode layer positioned between first and second dielectric plates; a channel extending through the first and second dielectric plates and the electrode layer; anda conductive coating covering at least a region of the electrode layer that is exposed to the channel;wherein the conductive coating and the electrode layer comprise different materials comprising different etch rates in an etchant, andwherein the etch rate of the conductive coating in the etchant is faster than the etch rate of the electrode layer in the etchant.2. The lithography apparatus of clause 1, the electrostatic clamp further comprising:one or more conductive components positioned in the channel and configured to provide an electrical path between an external component and the electrode layer, wherein the conductive coating is included in the electrical path.3. The lithography apparatus of clause 2, wherein the one or more conductive components include one or more of a conductive pin, spring, flexure, wire, solder, paste, adhesive, or epoxy.4. The lithography apparatus of clause 2, wherein the one or more conductive components include a conductive sheath deposited along a portion of at least one of the first and second dielectric plates that is exposed to the channel.5. The lithography apparatus of clause 1 , wherein the first and second dielectric plates are arranged to exhibit an etch rate in the etchant that is slower than the etch rate of the conductive coating in the etchant.6. The lithography apparatus of clause 1, wherein the etch rate of the conductive coating in the etchant is at least two times faster than the etch rate of the electrode layer in the etchant.7. The lithography apparatus of clause 1, wherein the etch rate of the conductive coating in the etchant is at least five times faster than the etch rate of the electrode layer in the etchant.8. The lithography apparatus of clause 1, wherein the etch rate of the conductive coating in the etchant is at least twenty times faster than the etch rate of the electrode layer in the etchant.9. The lithography apparatus of clause 1, wherein:the electrode layer comprises chromium;the conductive coating comprises a titanium tungsten alloy; andthe etchant comprises hydrogen peroxide.10. The lithography apparatus of clause 1, wherein:the electrode layer comprises chromium;the conductive coating comprises tungsten; andthe etchant comprises hydrogen peroxide.11. The lithography apparatus of clause 1, wherein:the electrode layer comprises chromium, tantalum, molybdenum, titanium tungsten, or niobium;the conductive coating comprises titanium, aluminum, or nickel; andthe etchant comprises sulfuric acid and hydrogen peroxide.12. The lithography apparatus of clause 1, wherein:the electrode layer comprises chromium;the conductive coating comprises titanium or titanium nitride; andthe etchant comprises sulfur hexafluoride, sulfur hexafluoride and argon, carbon tetrafluoride, carbon tetrafluoride and argon, fluoroform, fluoroform and argon, chlorine gas, or chlorine gas and argon.13. An electrostatic clamp, comprising:an electrode layer positioned between first and second dielectric plates;a channel extending through the first and second dielectric plates and the electrode layer; and a conductive coating covering at least a region of the electrode layer that is exposed to the channel;wherein the conductive coating and the electrode layer comprise different materials comprising different etch rates in an etchant, andwherein the etch rate of the conductive coating in the etchant is faster than the etch rate of the electrode in the etchant.14. The electrostatic clamp of clause 13, further comprising:one or more conductive components positioned in the channel and configured to provide an electrical path between an external component and the electrode layer, wherein the conductive coating is included in the electrical path.15. The electrostatic clamp of clause 14, wherein the one or more conductive components include one or more of a conductive pin, spring, flexure, wire, solder, paste, adhesive, or epoxy.16. The electrostatic clamp of clause 14, wherein the one or more conductive elements include a conductive sheath deposited along a portion of at least one of the first and second dielectric plates that is exposed to the channel.17. The electrostatic clamp of clause 13, wherein the first and second dielectric plates comprise an etch rate in the etchant that is slower than the etch rate of the conductive coating in the etchant such that the etchant does not etch the first and second dielectric plates.18. The electrostatic clamp of clause 13, wherein the etch rate of the conductive coating in the etchant is at least two times faster than the etch rate of the electrode layer in the etchant.19. The electrostatic clamp of clause 13, wherein the etch rate of the conductive coating in the etchant is at least five times faster than the etch rate of the electrode layer in the etchant.20. The electrostatic clamp of clause 13, wherein the etch rate of the conductive coating in the etchant is at least twenty times faster than the etch rate of the electrode layer in the etchant.21. The electrostatic clamp of clause 13, wherein:the electrode layer comprises chromium;the conductive coating comprises a titanium tungsten alloy; andthe etchant comprises hydrogen peroxide.22. The electrostatic clamp of clause 13, wherein:the electrode layer comprises chromium;the conductive coating comprises tungsten; andthe etchant comprises hydrogen peroxide.23. The electrostatic clamp of clause 13, wherein:the electrode layer comprises chromium, tantalum, molybdenum, titanium tungsten, or niobium;the conductive coating comprises titanium, aluminum, or nickel; andthe etchant comprises sulfuric acid and hydrogen peroxide.24. The electrostatic clamp of clause 13, wherein:the electrode layer comprises chromium;the conductive coating comprises titanium or titanium nitride; andthe etchant comprises sulfur hexafluoride, sulfur hexafluoride and argon, carbon tetrafluoride, carbon tetrafluoride and argon, fluoroform, fluoroform and argon, chlorine gas, or chlorine gas and argon.25. A method, comprising:exposing a conductive coating of an electrostatic clamp, the electrostatic clamp comprising an electrode layer positioned between first and second dielectric plates with a channel extending through the dielectric plates and the electrode layer, and the conductive coating covering at least a region of an electrode layer that is exposed to the channel; andetching the conductive coating using an etchant that comprises a faster etch rate for the conductive coating than for the electrode layer.26. The method of clause 25, wherein the etch rate of the conductive coating in the etchant is at least two times faster than the etch rate of the electrode layer in the etchant.27. The method of clause 25, wherein the etch rate of the conductive coating in the etchant is at least five times faster than the etch rate of the electrode layer in the etchant.28. The method of clause 25, wherein the etch rate of the conductive coating in the etchant is at least twenty times faster than the etch rate of the electrode layer in the etchant.29. The method of clause 25, wherein:the electrode layer comprises chromium;the conductive coating comprises a titanium tungsten alloy; andthe etchant comprises hydrogen peroxide.30. The method of clause 25, wherein:the electrode layer comprises chromium;the conductive coating comprises tungsten; andthe etchant comprises hydrogen peroxide.31. The method of clause 25, wherein:the electrode layer comprises chromium, tantalum, molybdenum, titanium tungsten, or niobium;the conductive coating comprises titanium, aluminum, or nickel; andthe etchant comprises sulfuric acid and hydrogen peroxide.32. The method of clause 25, wherein:the electrode layer comprises chromium;the conductive coating comprises titanium or titanium nitride; andthe etchant comprises sulfur hexafluoride, sulfur hexafluoride and argon, carbon tetrafluoride, carbon tetrafluoride and argon, fluoroform, fluoroform and argon, chlorine gas, or chlorine gas and argon.33. A method of manufacturing an electrostatic clamp, the method comprising:positioning an electrode layer between first and second dielectric plates;forming a channel that extends through the first and second dielectric plates and the electrode layer; anddepositing a conductive coating that covers at least a region of the electrode layer that is exposed to the channel;wherein the conductive coating and the electrode layer comprise different materials comprising different etch rates in an etchant, andwherein the etch rate of the conductive coating in the etchant is faster than the etch rate of the electrode layer in the etchant.34. The method of clause 33, further comprising:positioning one or more conductive components in the channel, the one or more conductive components configured to provide an electrical path between an external component and the electrode layer, wherein the conductive coating is included in the electrical path.35. The method of clause 34, wherein the one or more conductive components include one or more of a conductive pin, spring, flexure, wire, solder, paste, adhesive, or epoxy.36. The method of clause 34, wherein the one or more conductive elements include a conductive sheath deposited along a portion of at least one of the first and second dielectric plates that is exposed to the channel.37. The method of clause 33, wherein the first and second dielectric plates comprise an etch rate in the etchant that is slower than the etch rate of the conductive coating in the etchant such that the etchant does not etch the first and second dielectric plates.38. The method of clause 33, wherein the etch rate of the conductive coating in the etchant is at least two times faster than the etch rate of the electrode layer in the etchant.39. The method of clause 33, wherein the etch rate of the conductive coating in the etchant is at least five times faster than the etch rate of the electrode layer in the etchant.40. The method of clause 33, wherein the etch rate of the conductive coating in the etchant is at least twenty times faster than the etch rate of the electrode layer in the etchant.41. The method of clause 33, wherein:the electrode layer comprises chromium;the conductive coating comprises a titanium tungsten alloy; andthe etchant comprises hydrogen peroxide.42. The method of clause 33, wherein:the electrode layer comprises chromium;the conductive coating comprises tungsten; andthe etchant comprises hydrogen peroxide.43. The method of clause 33, wherein:the electrode layer comprises chromium, tantalum, molybdenum, titanium tungsten, or niobium;the conductive coating comprises titanium, aluminum, or nickel; andthe etchant comprises sulfuric acid and hydrogen peroxide.44. The method of clause 33, wherein:the electrode layer comprises chromium;the conductive coating comprises titanium or titanium nitride; andthe etchant comprises sulfur hexafluoride, sulfur hexafluoride and argon, carbon tetrafluoride, carbon tetrafluoride and argon, fluoroform, fluoroform and argon, chlorine gas, or chlorine gas and argon.

[0094] The present disclosure has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building 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. The foregoing description of specific aspects will so fully reveal the general nature of the present disclosure that others can, by applying knowledge within the skill of the art, readily modify and / or adapt for various applications such specific aspects, without undue experimentation and without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed aspects, based on the teaching and guidance presented herein.

[0095] It is to be understood that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections can set forth one or more, but not necessarily all, aspects of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way. The breadth and scope of the protected subject matter should not be limited by any of the above -de scribed aspects, but should be defined in accordance with the following claims and their equivalents.

Claims

CLAIMS1. A lithography apparatus, comprising:an electrostatic clamp comprising:an electrode layer positioned between first and second dielectric plates; a channel extending through the first and second dielectric plates and the electrode layer; anda conductive coating covering at least a region of the electrode layer that is exposed to the channel;wherein the conductive coating and the electrode layer comprise different materials comprising different etch rates in an etchant, andwherein the etch rate of the conductive coating in the etchant is faster than the etch rate of the electrode layer in the etchant.

2. The lithography apparatus of claim 1, the electrostatic clamp further comprising:one or more conductive components positioned in the channel and configured to provide an electrical path between an external component and the electrode layer, wherein the conductive coating is included in the electrical path.

3. The lithography apparatus of claim 2, wherein the one or more conductive components include one or more of a conductive pin, spring, flexure, wire, solder, paste, adhesive, or epoxy.

4. The lithography apparatus of claim 2, wherein the one or more conductive components include a conductive sheath deposited along a portion of at least one of the first and second dielectric plates that is exposed to the channel.

5. The lithography apparatus of claim 1 , wherein the first and second dielectric plates are arranged to exhibit an etch rate in the etchant that is slower than the etch rate of the conductive coating in the etchant.

6. An electrostatic clamp, comprising:an electrode layer positioned between first and second dielectric plates;a channel extending through the first and second dielectric plates and the electrode layer; and a conductive coating covering at least a region of the electrode layer that is exposed to the channel;wherein the conductive coating and the electrode layer comprise different materials comprising different etch rates in an etchant, andwherein the etch rate of the conductive coating in the etchant is faster than the etch rate of the electrode in the etchant.

7. The electrostatic clamp of claim 6, further comprising:one or more conductive components positioned in the channel and configured to provide an electrical path between an external component and the electrode layer, wherein the conductive coating is included in the electrical path.

8. The electrostatic clamp of claim 7, wherein the one or more conductive components include one or more of a conductive pin, spring, flexure, wire, solder, paste, adhesive, or epoxy.

9. The electrostatic clamp of claim 7, wherein the one or more conductive elements include a conductive sheath deposited along a portion of at least one of the first and second dielectric plates that is exposed to the channel.

10. The electrostatic clamp of claim 6, wherein the first and second dielectric plates comprise an etch rate in the etchant that is slower than the etch rate of the conductive coating in the etchant such that the etchant does not etch the first and second dielectric plates.

11. A method of manufacturing an electrostatic clamp, the method comprising:positioning an electrode layer between first and second dielectric plates;forming a channel that extends through the first and second dielectric plates and the electrode layer; anddepositing a conductive coating that covers at least a region of the electrode layer that is exposed to the channel;wherein the conductive coating and the electrode layer comprise different materials comprising different etch rates in an etchant, andwherein the etch rate of the conductive coating in the etchant is faster than the etch rate of the electrode layer in the etchant.

12. The method of claim 11, further comprising:positioning one or more conductive components in the channel, the one or more conductive components configured to provide an electrical path between an external component and the electrode layer, wherein the conductive coating is included in the electrical path.

13. The method of claim 12, wherein the one or more conductive components include one or more of a conductive pin, spring, flexure, wire, solder, paste, adhesive, or epoxy.

14. The method of claim 12, wherein the one or more conductive elements include a conductive sheath deposited along a portion of at least one of the first and second dielectric plates that is exposed to the channel.

15. The method of claim 11, wherein the first and second dielectric plates comprise an etch rate in the etchant that is slower than the etch rate of the conductive coating in the etchant such that the etchant does not etch the first and second dielectric plates.

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