Method of structuring burls and grounding lines on a clamp apparatus

Abstract

A method of forming burls and grounding lines includes disposing at least one material layer at a first height on a surface of an object. The method further includes positioning a first mask over a core portion of the at least one material layer. The method further includes partially etching, for a selected time period, a selected portion of the at least one material layer adjacent to the core portion until the selected portion is at a second height that is less than the first height such that at least one burl is formed. The method further includes positioning a second mask over the core portion and the selected portion. The method further includes fully etching a remaining portion of the at least one material layer to expose the surface of the object such that at least one grounding line is formed from the selected portion at the second height.

Description

METHOD OF STRUCTURING BURLS AND GROUNDING LINES ON A CLAMP APPARATUSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the priority benefit of U.S. Provisional Patent Application Number 63 / 779,461, filed March 28, 2025, and European Patent Application Number 26152817.8, filed lanuary 20, 2026, the contents of which are incorporated by reference herein in their entireties.FIELD

[0002] The present disclosure relates to support structures, for example, wafer clamps or reticle clamps in lithographic 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 may 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] Another lithographic system is an interferometric lithographic system where there is no patterning device, but rather a light beam is split into two beams, and the two beams are caused to interfere at a target portion of the substrate through the use of a reflection system. The interference causes lines to be formed at the target portion of the substrate.

[0005] During lithographic operation, different processing steps can entail different layers to be sequentially formed on the substrate. Accordingly, it can be necessary to position the substrate relative to prior patterns formed thereon with a high degree of accuracy. Generally, alignment marks are placed on the substrate to be aligned and are located with reference to a second object. A lithographic apparatus may use an alignment apparatus for detecting positions of the alignment marks and for aligning the substrate using the alignment marks to ensure accurate exposure from a mask. Misalignment between the alignment marks at two different layers is measured as overlay error.

[0006] In order to monitor the lithographic process, parameters of the patterned substrate are measured. Parameters may include, for example, the overlay error between successive layers formed in or on the patterned substrate and critical linewidth of developed photosensitive resist. This measurement can be performed on a product substrate and / or on a dedicated metrology target. There are various techniques for making measurements of the microscopic structures formed in lithographic processes, including the use of scanning electron microscopes and various specialized tools. A fast and non-invasive form of a specialized inspection tool is a scatterometer in which a beam of radiation is directed onto a target on the surface of the substrate and properties of the scattered or reflected beam are measured. By comparing the properties of the beam before and after it has been reflected or scattered by the substrate, the properties of the substrate can be determined. This can be done, for example, by comparing the reflected beam with data stored in a library of known measurements associated with known substrate properties. Spectroscopic scatterometers direct a broadband radiation beam onto the substrate and measure the spectrum (intensity as a function of wavelength) of the radiation scattered into a particular narrow angular range. By contrast, angularly resolved scatterometers use a monochromatic radiation beam and measure the intensity of the scattered radiation as a function of angle.

[0007] Such optical scatterometers can be used to measure parameters, such as critical dimensions of developed photosensitive resist or overlay error (OV) between two layers formed in or on the patterned substrate. Properties of the substrate can be determined by comparing the properties of an illumination beam before and after the beam has been reflected or scattered by the substrate.

[0008] A substrate table can include a wafer clamp configured to hold a substrate. The wafer clamp can include a plurality of burls that are configured to support the substrate. The wafer clamp can include an electrode underneath the burls that generates an electrostatic force to secure the substrate to the wafer clamp. The burls can be electrically grounded to each other and to a ground plane of the wafer clamp via grounding lines. Accordingly, when the substrate sits on the burls, the wafer also is grounded through the grounding lines.

[0009] The plurality of burls can be formed via an etching process. Existing manufacturing methods can include disposing a thin coating of grounding material over etched burl cores and etching the thin coating to form grounding lines. These existing manufacturing methods can have numerous disadvantages. First, the thin coating can cause various manufacturing issues related to the grounding lines. For example, grounding lines formed from the thin coating are prone to breaking and edge geometry issues, which can cause sections of burls to become electrically isolated and at risk of high-voltage discharge and blowouts. Second, the process of adding the thin coating over the burl cores to the wafer clamp can create structural issues within the burls. Adjacent material layers can have different thicknesses and therefore can have different internal stresses which may cause one material layer to pull or push on another material layer. Additionally, the connection point between material layers may contain imperfections, impurities, and / or discontinuities, all of which can further contribute to the different internal stresses. As a result, overcoating the burl cores may be creating an undesirabledifference in internal stresses that cause the burls to have a corona effect (e.g., raised edges along the perimeter) instead of a flat surface. Third, the existing manufacturing process can be wasteful for both time and resources. Some manufacturers may perform coating processes and etching processes in separate locations, which introduces inefficiencies when repeatedly moving components between locations to perform alternating coating processes and etching processes.SUMMARY

[0010] Accordingly, it is desirable to develop a method that can form burls and grounding lines having a structure without defects in a more efficient manner. For example, a method that uses one coating step to a final height and a partial etching step can provide a cost-effective and reliable process for structuring flat burls and unbroken grounding lines on a clamp apparatus.

[0011] In some aspects, a method of forming burls and grounding lines can include disposing at least one material layer at a first height on a surface of an object. The method can further include positioning a first mask over a core portion of the at least one material layer. The method can further include partially etching, for a selected time period, a selected portion of the at least one material layer adjacent to the core portion until the selected portion is at a second height that is less than the first height such that at least one burl is formed from the core portion at the first height. The method can further include positioning a second mask over the core portion and the selected portion. The method can further include fully etching a remaining portion of the at least one material layer to expose the surface of the object such that at least one grounding line is formed from the selected portion at the second height.

[0012] In some aspects, an apparatus can include an object, at least one burl, and at least one grounding line. The object can include a surface. The at least one burl can include at least one material layer disposed at a first height on the surface. Each of the at least one burl can be formed by a partial etch, for a selected time period, to a second height of a selected portion of the at least one material layer adjacent to a corresponding core portion of the at least one material layer. The second height can be less than the first height. The at least one grounding line can be formed by the partial etch, for the selected time period, to the second height of the selected portion and a full etch of a remaining portion of the at least one material layer that exposes the surface. The at least one grounding line can be configured to connect the at least one burl to a common ground.

[0013] In some aspects, a lithographic system can include an illumination system, a patterning system, a projection system, and a clamp apparatus. The illumination system can be configured to condition a radiation beam. The patterning system can be configured to impart a pattern onto the radiation beam to form a patterned beam. The projection system can be configured to project the patterned beam onto a substrate. The clamp apparatus can include an object, at least one burl, and at least one grounding line. The object can include a surface. The at least one burl can include at least one material layer disposed at a first height on the surface . Each of the at least one burl can be formed by a partial etch, for a selected time period, to a second height of a selected portion of the at least one material layer adjacent to acorresponding core portion of the at least one material layer. The second height can be less than the first height. The at least one grounding line can be formed by the partial etch, for the selected time period, to the second height of the selected portion and a full etch of a remaining portion of the at least one material layer that exposes the surface . The at least one grounding line can be configured to connect the at least one burl to a common ground.

[0014] 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

[0015] 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.

[0016] FIG. 1A shows a reflective lithographic apparatus, according to some aspects.

[0017] FIG. IB shows a transmissive lithographic apparatus, according to some aspects.

[0018] FIG. 2 shows more details of a reflective lithographic apparatus, according to some aspects.

[0019] FIG. 3 shows a lithographic cell, according to some aspects.

[0020] FIG. 4 shows a substrate stage, according to some aspects.

[0021] FIG. 5A-5D show cross-section views of various aspects of an apparatus that includes a structure of burls and grounding lines, according to some aspects.

[0022] FIG. 6 shows a top view of an apparatus that includes a structure of burls and grounding lines, according to some aspects.

[0023] FIG. 7 shows a method of forming burls and grounding lines, according to some aspects.

[0024] FIGS. 8A-8F show cross-section views of structures formed at corresponding method steps described in FIG. 7, according to some aspects.

[0025] 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 indicate identical, 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

[0026] 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.

[0027] 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 may likewise be interpreted accordingly.

[0028] The terms “about,” “approximately,” or the like can be used herein to 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).

[0029] Aspects of the present disclosure can be implemented in hardware, firmware, software, or any combination thereof. Aspects of the disclosure can also be implemented as instructions stored on a computer-readable medium, which can be read and executed by one or more processors. A machine-readable medium can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium can include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Furthermore, firmware, software, routines, and / or instructions can be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc. The term “machine-readable medium” can be interchangeable with similar terms, for example, “computer program product,” “computer-readable medium,” “non-transitory computer-readable medium,” or the like. The term “non-transitory” can be used herein to characterize one or more forms of computer readable media except for a transitory, propagating signal.

[0030] 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.

[0031] Example Lithographic Systems

[0032] FIGS. 1A and IB show 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’ 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 the 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 the substrate W. Lithographic apparatus 100 and 100’ also have a projection system PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion (for example, comprising one or more dies) C of the substrate W. In lithographic apparatus 100, the patterning device MA and the projection system PS are reflective. In lithographic apparatus 100’, the patterning device MA and the projection system PS are transmissive.

[0033] The illumination system IL can include 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.

[0034] The support structure MT holds the 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 or not the patterning device MA is held in a vacuum environment. The support structure MT can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. The support structure MT can be a frame or a table, for example, which can be fixed or movable. By using sensors, the support structure MT can ensure that the patterning device MA is at a desired position, for example, with respect to the projection system PS.

[0035] The term “patterning device” MA should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section, such as to create a pattern in the target portion C of the substrate W. The pattern imparted to the radiation beam B can correspond to a particular functional layer in a device being created in the target portion C to form an integrated circuit.

[0036] The patterning device MA can be transmissive (as in lithographic apparatus 100’ of FIG. IB) or reflective (as in lithographic apparatus 100 of FIG. 1A). Examples of patterning devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks are well known in lithography, and include 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 incomingradiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam B, which is reflected by a matrix of small mirrors.

[0037] The term “projection system” PS can encompass 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. A vacuum environment can be used for EUV or electron beam radiation since other gases can absorb too much radiation or electrons. A vacuum environment can therefore be provided to the whole beam path with the aid of a vacuum wall and vacuum pumps.

[0038] 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, the additional substrate tables WT can be used in parallel, or preparatory steps can be carried out on one or more tables while one or more other substrate tables WT are being used for exposure. In some situations, the additional table may not be a substrate table WT.

[0039] The lithographic apparatus can also be of a type wherein 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 are well known in the art for increasing the numerical aperture of projection systems. The term “immersion” as used herein does not mean that a structure, such as a substrate, must be submerged in liquid. For example, a liquid can be located between the projection system and the substrate during exposure.

[0040] Referring to FIGS. 1A and IB, the illuminator IL receives a radiation beam from a radiation source SO. The source SO and the lithographic apparatus 100, 100’ can be separate physical entities, for example, when the source SO is an excimer laser. In such cases, the source SO is not considered to form part of the lithographic apparatus 100 or 100’, and the radiation beam B passes from the source SO to the illuminator IL with the aid of a beam delivery system BD (in FIG. IB) including, for example, suitable directing mirrors and / or a beam expander. In other cases, the source SO can be an integral part of the lithographic apparatus 100, 100 ’, for example, when the source SO is a mercury lamp . A radiation system can comprise the source SO, the illuminator IL, and / or the beam delivery system BD.

[0041] The illuminator IL can 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 “n-outer” and “n-inner,” respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL can comprise various other components (in FIG. IB), such as an integrator IN and a condenser CO. The illuminator IL can be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross section.

[0042] 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 the patterning device (for example, mask) MA. After being reflected from the patterning 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 can 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 can be used to accurately position the patterning device (for example, mask) MA with respect to the path of the radiation beam B. Patterning device (for example, mask) MA and substrate W can be aligned using mask alignment marks Ml, M2 and substrate alignment marks PI, P2.

[0043] Referring to FIG. IB, 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. 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 pattern without being affected by diffraction at the mask pattern and create an image of the intensity distribution at the illumination system pupil IPU.

[0044] The projection system PS projects an image of the mask pattern MP, where the image is formed by diffracted beams produced from the mark pattern MP by radiation from the intensity distribution, onto a photoresist layer coated on the substrate W. For example, the mask pattern MP can 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 pattern 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.

[0045] The projection system PS is arranged to capture (e.g., using a lens or lens group U) the zeroth order diffracted beams, first order diffracted beams, and / or higher order diffracted beams (not shown). In some aspects, dipole illumination for imaging line patterns extending in a direction perpendicular to a line can 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 pattern MP at highest possible resolution and process window (i.e., usable depth of focus in combination with tolerable exposure dose deviations). In some aspects, astigmatism aberration can be reduced by providing radiation poles (not shown) in opposite quadrants of the illumination system pupil IPU. Further, in some aspects, astigmatism aberration can 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 B2, issued Mar. 31, 2009, the contents of which are incorporated by reference herein in its entirety.

[0046] 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 can 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) can 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).

[0047] In general, movement of the mask table MT can be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate table WT can be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask table MT can be connected to a short-stroke actuator or can be fixed. Mask MA and substrate W can 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 can be located in spaces between target portions (known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the mask MA, the mask alignment marks can be located between the dies.

[0048] Mask table MT and patterning device MA can be in a vacuum chamber V, where an in-vacuum robot IVR can be used to move patterning devices such as a mask in and out of vacuum chamber. Alternatively, when mask table MT and patterning device MA are outside of the vacuum chamber, an out-of-vacuum robot can be used for various transportation operations, similar to the in-vacuum robot IVR. Both the in-vacuum and out-of-vacuum robots can be calibrated for a smooth transfer of any payload (e.g., mask) to a fixed kinematic mount of a transfer station.

[0049] The lithographic apparatus 100 and 100’ can be used in at least one of the following modes:

[0050] 1. In step mode, the support structure (for example, mask table) MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam B is projected onto a target portion C at one time (i.e., a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed.

[0051] 2. In scan mode, the support structure (for example, mask table) MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam B is projected ontoa target portion C (i.e., a single dynamic exposure). The velocity and direction of the substrate table WT relative to the support structure (for example, mask table) MT can be determined by the (de-)magnification and image reversal characteristics of the projection system PS.

[0052] 3. In another mode, the support structure (for example, mask table) MT is kept substantially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. A pulsed radiation source SO can be employed and the programmable patterning device is updated as needed after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes a programmable patterning device, such as a programmable mirror array.

[0053] Combinations and / or variations on the described modes of use or entirely different modes of use can also be employed.

[0054] In a further aspect, 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.

[0055] FIG. 2 shows the lithographic apparatus 100 in more detail, including the source collector apparatus SO, the illumination system IL, and the projection system PS. The source collector apparatus SO is constructed and arranged such that a vacuum environment can be maintained in an enclosing structure 201 of the source collector apparatus SO. An EUV radiation emitting plasma 202 can be formed by a discharge produced plasma source. EUV radiation can be produced by a gas or vapor, for example Xe gas, Li vapor, or Sn vapor in which EUV radiation emitting plasma 202 is created to emit radiation in the EUV range of the electromagnetic spectrum. The EUV radiation emitting plasma 202 is created by, for example, an electrical discharge causing at least a partially ionized plasma. Partial pressures of, for example, 10 Pa of Xe, Li, Sn vapor, or any other suitable gas or vapor can be used for efficient generation of the radiation. In some aspects, a plasma of excited tin (Sn) (e.g., excited via a laser) is provided to produce EUV radiation.

[0056] The radiation emitted by the EUV radiation emitting plasma 202 is passed from a source chamber 203 into a collector chamber 204 via an optional gas barrier or contaminant trap 205 (in some cases also referred to as contaminant barrier or foil trap), which is positioned in or behind an opening in source chamber 203. The contaminant trap 205 can include a channel structure. Contamination trap 205 can also include a gas barrier or a combination of a gas barrier and a channel structure. The contaminant trap 205 (or contaminant barrier) further indicated herein at least includes a channel structure.

[0057] The collector chamber 204 can include a radiation collector CO, which can be a so-called grazing incidence collector. Radiation collector CO has an upstream radiation collector side 206 and a downstream radiation collector side 207. Radiation that traverses collector CO can be reflected off agrating spectral filter 208 to be focused in a virtual source point INTF. The virtual source point INTF is commonly referred to as the intermediate focus, and the source collector apparatus is arranged such that the intermediate focus INTF is located at or near an opening 209 in the enclosing structure 201. The virtual source point INTF is an image of the EUV radiation emitting plasma 202. Grating spectral filter 208 is used in particular for suppressing infra-red (IR) radiation.

[0058] Subsequently the radiation traverses the illumination system IL, which can include a faceted field mirror device 210 and a faceted pupil mirror device 211 arranged to provide a desired angular distribution of beam of radiation 212, at the patterning device MA, as well as a desired uniformity of radiation intensity at the patterning device MA. Upon reflection of the beam of radiation 212 at the patterning device MA, held by the support structure MT, a patterned beam 213 is formed and the patterned beam 213 is imaged by the projection system PS via reflective elements 214, 215 onto a substrate W held by the wafer stage or substrate table WT.

[0059] More elements than shown can generally be present in illumination optics unit IL and projection system PS. The grating spectral filter 208 can optionally be present, depending upon the type of lithographic apparatus. Further, there can be more mirrors present than those shown in the FIG. 2, for example there can be one to six additional reflective elements present in the projection system PS than shown in FIG. 2.

[0060] Collector optic CO, as illustrated in FIG. 2, is depicted as a nested collector with grazing incidence reflectors 216, 217, and 218, just as an example of a collector (or collector mirror). The grazing incidence reflectors 216, 217, and 218 are disposed axially symmetric around an optical axis O and a collector optic CO of this type is preferably used in combination with a discharge produced plasma source, often called a DPP source.

[0061] Example Lithographic Cell

[0062] FIG. 3 shows a lithographic cell 300, also sometimes referred to a lithocell or cluster, according to some aspects. Lithographic apparatus 100 or 100’ can form part of lithographic cell 300. Lithographic cell 300 can also include one or more apparatuses to perform pre- and post-exposure processes on a substrate. Conventionally these include spin coaters SC to deposit resist layers, developers DE to develop exposed resist, chill plates CH, and bake plates BK. A substrate handler, or robot, 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 the 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.

[0063] Example Substrate Table

[0064] FIG. 4 shows a substrate stage 420, according to some aspects. In some aspects, substrate stage 420 can comprise a substrate table 421, a support structure 422, and one or more sensors 423. Supportstructure 422 can be a frame of an actuated translation stage. Substrate table 421 and one or more sensors 423 are disposed on support structure 422. Substrate table 421 can comprise a clamp (e.g., an electrostatic clamp) to hold a substrate 424. The clamp can include a plurality of burls configured to support the substrate 424. Substrate stage 420 can be implemented in a lithographic apparatus. FIG. 4 illustrates components of a lithographic apparatus, such as projection system 425, a patterning device 426, and a computing system 427. Patterning device 426 can comprise one or more targets 428. Projection system 425, patterning device 426, and one or more targets 428 can be implemented in lithographic apparatus 100 / 100' as projection system PS, mask MA, and alignment marks M1 / M2 respectively (FIGS. 1A and IB).

[0065] In some aspects, one or more sensors 423 can be used to accurately position substrate table 421 and substrate 424 relative to projection system 425 and patterning device 426. Radiation scattered by one or more targets 428 can be received at one or more sensors 423. Computing system 427 can analyze measurement signals from one or more sensors 423 to determine an alignment position of substrate table 421 and / or substrate 424 relative to patterning device 426.

[0066] Example Apparatus with a Structure of Burls and Grounding Lines

[0067] Various aspects of an apparatus including a structure of burls and grounding lines are described herein with reference to FIGS. 5A-5D and 6. In some aspects, the apparatus can include burls and grounding lines that have been formed by aspects of a structuring method, as described below with reference to FIGS. 7 and 8A-8F. For example, the burls and grounding lines can be formed by a method step for disposing at least one material layer to a final height and method steps for partial etching of selected material portions and full etching of remaining material portions. The resulting structure of the apparatus formed by the structuring method can offer numerous advantages over existing apparatuses. For example, the burls can have a flat surface with a minimal or no corona effect and the grounding lines can be resistant to breakages. As a result, the apparatus can support an article such as, for example, a wafer or a reticle, in a reliable manner in a lithographic system.

[0068] FIG. 5A-5D show cross-section views of various aspects of an apparatus (collectively termed apparatus 530) that includes a structure of burls and grounding lines, according to some aspects. In some aspects, apparatus 530 can be a clamp apparatus incorporated into aspects of lithographic apparatus 100 and a lithographic apparatus 100’ as shown in and described with reference to FIGS. 1A and IB. It is understood that FIGS. 5A-5D merely illustrate a portion of apparatus 530 and that apparatus 530 can include a plurality of burls and corresponding grounding lines.

[0069] In some aspects, FIG. 5A shows a cross-section view of an example aspect of apparatus 530, referred to as apparatus 530A. In some aspects, apparatus 530A can include an object 531, at least one burl 532, and at least one grounding line 534. Specifically, apparatus 530A can include a structure of at least one burl 532 and at least one grounding line 534 formed from a single material layer on object 531.

[0070] In some aspects, object 531 can be configured to hold an article, such as a substrate (e.g., a wafer or a reticle), in a fixed plane on a support structure. In some aspects, object 531 can use mechanical, vacuum, electrostatic, or other suitable clamping techniques to hold and secure the article. In some aspects, object 531 can be an electrostatic clamp, which can be configured to electrostatically clamp (i.e., hold) the article. For example, object 531 can include for example (this detail shown on Figure 5A only) an electrode 560, a resistive layer on the electrode 561 and a dielectric layer 562 on the resistive layer. Other electrode and / or dielectric layer arrangements are possible, this is only a simple example. The object 531 may also comprise at least one burl 532 projecting from a surface 536 (e.g., a surface of the dielectric layer). In use, a voltage can be applied to object 531, for example, several kV. And current can flow through the resistive layer, such that the voltage at an upper surface of the resistive layer will substantially be the same as the voltage of the electrode and generate an electric field. Also, a Coulomb force, an attractive force between electrically opposite charged particles, will attract the article to object 531 and hold the article in place. In some aspects, object 531 can be made from a rigid material, for example, a metal, a dielectric, a ceramic, or a combination thereof. For example, object 531 can be made from a smooth, flat glass material.

[0071] In some aspects, object 531 can be a wafer clamp configured to support an article such as, for example, a substrate. In this example, object 531 can be a wafer clamp component of substrate table WT that supports substrate W as shown in and described with reference to FIGS. 1A and IB or a wafer clamp component of substrate table 421 that supports substrate 424 as shown in and described with reference to FIG. 4. In some aspects, object 531 can be a reticle clamp configured to support an article such as, for example, a reticle of a patterning system. In this example, object 531 can be a reticle clamp component of support structure MT that supports patterning device MA as shown in and described with reference to FIGS. 1A and IB. Aspects described herein primarily may refer to object 531 as a wafer clamp, but it is understood that object 531 can be a reticle clamp upon which at least one burl 532 and at least one grounding line 534 are formed.

[0072] In some aspects, at least one burl 532 can be formed on surface 536 of object 531. For clarity of illustration, the example aspect of FIG. 5A depicts two burls 532 adjacent to each other to indicate how a plurality of burls 532 can be arranged in sequence on object 531. It is understood that any number of burls 532 can be arranged on object 531, ranging from at least one burl 532 to hundreds or thousands of burls 532. Adjacent ones of burls 532 can be any distance apart relative to each other. For example, adjacent ones of burls 532 can be millimeters apart.

[0073] In some aspects, the at least one burl 532 can be made from at least one material layer 540 disposed at a first height 542 on surface 536 of object 531. In some aspects, the at least one material layer 540 can include any material suitable for use in manufacturing performed by a lithographic apparatus (e.g., the manufacture of ICs). For example, in some aspects, the at least one material layer 540 can include at least one layer of chrome nitride (CrN), titanium nitride (TiN), boron-doped diamond, phosphorus-doped diamond, diamond-like coating, or the like. The term “disposed” caninclude similar terms, for example, “deposited,” “put down,” “placed,” “added,” “built up,” or the like. In the example aspect shown in FIG. 5A, the at least one burl 532 can be made from a single material layer 540. In some aspects, first height 542 can be any selected height that is desired for the final height of the at least one burl 532. First height 542 can be a height that is sufficient for maintaining an attractive electrostatic force that holds an article in place on object 531. For example, first height 542 can be a selected number of microns.

[0074] In some aspects, each of the at least one burl 532 can be formed by a partial etch, for a selected time period, to a second height 548 of a selected portion 546 of the at least one material layer 540 adjacent to a corresponding main or “core” portion 538 of the at least one material layer 540. In some aspects, each core portion 538 can be a designated region where a burl 532 is formed. Each core portion 538 can be designated by a first mask pattern to be protected at this step in the structuring method. In some aspects, each selected portion 546 can be a designated region adjacent to where a burl 532 is formed. Each selected portion 546 can be designated by the first mask pattern to be exposed at this step in the structuring method. In some aspects, second height 548 can be any selected height that is less than first height 542. Second height 548 can be a height that provides sufficient space for backflow gas to flow under the article supported by object 531. For example, second height 548 can be a selected number of microns that is lower than the selected number of microns for the first height 542.

[0075] In some aspects, the partial etch that forms each of the at least one burl 532 can be any type of surface etching process in which a selected area of material (e.g., core portion 538) is protected by a mask and / or a patterned photoresist. For example, each of the at least one burl 532 can be formed by a partial etch that is a liquid etch, a reactive ion etch, or a laser machining process of selected portion 546 to second height 548. In aspects in which the at least one material layer 540 is made from chrome nitride, the at least one burl 532 can be formed by a partial etch that is a liquid etch. The liquid etch can be performed in a recirculating etching chamber so that the etching rate is substantially uniform across a full surface area of object 531. In aspects in which the at least one material layer 540 is made from a type of diamond material, the at least one burl 532 can be formed by a partial etch that is a reactive ion etch (RIE). It can be beneficial to use the partial etch to form the at least one burl 532 and the at least one grounding line 534 out of conductive diamond because types of diamond material can be resistant to wear over many uses.

[0076] In an example, the etching to form the burls may use a dry etching process such as RIE, or more specifically Reactive Ion Etching combined with Inductively Coupled Plasma (RIE-ICP). The etching thickness can be controlled with a high accuracy using RIE-ICP. RIE-ICP also provides for anisotropic etching. Structuring of the material (e.g., Chromium Nitride CrN or diamond) using anisotropic RIE-ICP technology enables the production of structures with a high etching rate control, low damage processing and very low chemical waste. The structures obtained are sharply defined with little or no over and / or under etching. The process is reliable and reproduceable.

[0077] It is also possible to control the RIE-ICP etching process via in situ measurement, e.g., using ellipsometry. For example, a laser may be reflected off the surface being etched, such that the surface’s reflectivity can be measured (e.g., by measuring the intensity of the reflected laser light). This can be used to detect an interface between material layers (e.g., of a multiple layer structure), e.g., by detecting a sudden change or jump in the reflectivity corresponding with the interface. Such in situ measurement and control is not possible with wet etching. The ability to detect material interfaces during the actual etch makes it possible to etch to (or shortly after) a particular interface by stopping the etch when an interface is detected.

[0078] When forming the at least one burl 532 via a partial etch, a top surface of the at least one burl 532 can be protected by the photoresist so the etchant never makes contact with the corresponding core portion 538. Additionally, the top surface of the at least one burl 532 may not be overcoated by another material (except for the photoresist that can be stripped away). Therefore, the top surface of the at least one burl 532 can be substantially flat with a comparatively low peak-to-valley (PV) range and with minimal or no corona effect. For example, the PV range of the top surface of the at least one burl 532 can be about a few nanometers.

[0079] In an RIE-ICP example, a hard mask may be formed and structured, prior to the burl structuring. Such a hard mask may be beneficial, for example when etching into CrN which has a low etching rate. The material to be etched (e.g., CrN) may have disposed thereon a hard mask layer (e.g., a silicon oxide SiOx such as silicon dioxide) and a resist layer. An initial lithography step exposes the burl pattern (i.e., defining core portion 538) into the resist layer, which is then etched to remove the resist from the unexposed portion (i.e., comprising selected portion 536) thereby forming an initial mask. The hard mask is then exposed and etched in an initial RIE-ICP hard mask structuring step; i.e., to form the first mask by removing the hard mask layer material at selected portion 546. This RIE-ICP hard mask structuring step may use a fluor-based etchant (e.g., combined with Argon and / or oxygen) for example: a Trifluoromethane (CHF3) with Argon (Ar) and / or oxygen (O2) gas mixture (e.g., CHFvAr) or a Tetrafluoromethane (CF4) with Argon (Ar) and / or oxygen gas mixture (e.g., CF^CE). An RIE-ICP burl structuring step can then be performed to partially etch the material of the selected portion 546 to second height 548. This RIE-ICP burl structuring step may, for example, use a chlorine based etchant such as a mixture of chlorine and oxygen gasses (CI2 / O2). An RIE-ICP hard mask removal step can then be performed to remove the hard mask from the top of the burls (e.g., using the same chemicals as the hard mask structuring step).

[0080] In some aspects, the at least one burl 532 can include a polished surface 544. For example, the top surface of the at least one material layer 540 can be polished before the photoresist is applied so that polished surface 544 can be protected at core portion 538 for a corresponding burl 532. The top surface of the at least one material layer 540 can be polished via a chemical solution (e.g., a non-abrasive compound) and / or a mechanical device (e.g., a polisher, a buffer, etc.). Such polishing cannot be achieved with existing manufacturing methods because an overcoating of a grounding material wouldcover any polished surface of a burl on an existing device. In contrast, polished surface 544 can ensure that each of the at least one burl 532 is sufficiently flat for supporting the article.

[0081] In some aspects, at least one grounding line 534 can be formed on surface 536 of object 531. For clarity of illustration, the example aspect of FIG. 5A depicts three segments of one grounding line 534 that connects two adjacent burls 532 on object 531. It is understood that any number of grounding lines 534 can be arranged on object 531, ranging from at least one grounding line 534 to hundreds or thousands of grounding lines 534. Adjacent ones of grounding lines 534 can be any distance apart relative to each other. For example, adjacent ones of grounding lines 534 can be millimeters apart.

[0082] In some aspects, each of the at least one grounding line 534 can be formed by the partial etch, for the selected time period, to second height 548 of selected portion 546 and a full etch of a remaining portion of the at least one material layer 540 that exposes surface 536 of object 531. In the example aspect shown in FIG. 5A, the at least one grounding line 534 can be made from the same single material layer 540 that forms the at least one burl 532 (or at least a lower portion of the at least one burl 532) such that the at least one burl 532 (or lower portion thereof) and the at least one grounding line 534 form a single continuous structure. In some aspects, each selected portion 546 can be a designated region where the at least one grounding line 534 is formed adjacent to a corresponding burl 532. Each selected portion 546 can be designated by a second mask pattern to be protected, along with corresponding core portions 538, at this step in the structuring method. Any remaining portion of the at least one material layer 540 can be designated by the second mask pattern to be exposed at this step in the structuring method.

[0083] In some aspects, the partial etch can form atop surface of the at least one grounding line 534. The partial etch can create or modify an internal crystal grain of the at least one material layer 540 at each selected portion 546, thereby forming a substantially rough surface. The top surface of the at least one grounding line 534 can have a comparatively high PV range. For example, the PV range of the top surface of the at least one grounding line 534 can be about hundreds of nanometers. The PV range of the top surface of the at least one grounding line 534 can be within a range that does not affect the electrical connectivity of the at least one grounding line 534 or the flow of the backflow gas under the article. Additionally, the roughness of the top surface of the at least one grounding line 534 can be acceptable because it does not make contact with the article.

[0084] In some aspects, the full etch can form sidewalls for each of the at least one grounding line 534. In some aspects, the full etch can be any type of surface etching process in which a selected area of material (e.g., core portion 538 and selected portion 546) is protected by a mask and / or a patterned photoresist. For example, each of the at least one grounding line 534 can be formed by a full etch that is a liquid etch, a reactive ion etch, or a laser machining process of any remaining portion of the at least one material layer 540 that exposes surface 536 of object 531. The full etch can be performed for a selected time period or can be performed until surface 536 of object 531 is exposed at any remainingportion of the at least one material layer 540. The sidewalls of each of the at least one grounding line 534 formed by the full etch can be substantially orthogonal to surface 536.

[0085] In the aforementioned RIE-ICP example, the full etch to form the at least one grounding line 534 may comprise an RIE-ICP grounding line structuring step. A resist layer is disposed, the grounding line pattern exposed and resist etched such that only the core portion 538 (burl tops) and the regions of the selected portion 546 corresponding to the at least one grounding line comprise resist. A RIE-ICP etch step etches the remaining portion (unmasked portion) of the at least one material layer 540 to expose the surface 536 of object 531. This RIE-ICP etch step may use a chlorine based etchant such as a mixture of chlorine and oxygen gasses (CI2 / O2). The resist may then be removed, e.g., in an ICP step (e.g., using Oxygen plasma).

[0086] In some aspects, the at least one grounding line 534 can be configured to connect the at least one burl 532 to a common ground 550. Common ground 550 can prevent an electrical short by electrically grounding each of burls 532 via grounding lines 534. For clarity of illustration, the example aspect of FIG. 5A depicts two burls 532 that can be connected in sequence by one grounding line 534 to common ground 550. It is understood that any number of burls 532 can be connected via any number of grounding lines 534 to common ground 550.

[0087] In some aspects, FIG. 5B shows a cross-section view of another example aspect of apparatus 530, referred to as apparatus 530B. In some aspects, apparatus 530B can be an alternative aspect of apparatus 530A as shown in and described with reference to FIG. 5A. The elements of apparatus 530B shown in FIG. 5B and the elements of apparatus 530A shown in FIG. 5A may be similar. Accordingly, the numbered elements previously described with regard to apparatus 530A can have the same structure and functions in apparatus 530B and the detailed description related to those elements is incorporated in the description of apparatus 530B. In some aspects, apparatus 530B can include an object 531, at least one burl 532, and at least one grounding line 534. Specifically, apparatus 530B can include a structure of at least one burl 532 and at least one grounding line 534 formed from a plurality of material layers (e.g., material layers 540a-540c) on object 531.

[0088] In some aspects, the at least one burl 532 can be made from at least one material layer disposed at first height 542 on surface 536 of object 531. For example, the at least one burl 532 can be made from a plurality of material layers successively disposed up to first height 542 on surface 536. The term “disposed” can include similar terms, for example, “deposited,” “put down,” “placed,” “added,” “built up,” or the like.

[0089] For clarity of illustration, the example aspect of FIG. 5B depicts the at least one burl 532 as made from three material layers 540a-540c that are disposed in sequence on surface 536: material layer 540a can be disposed first as a “bottom” material layer, material layer 540b can be disposed second as a “middle” material layer, and material layer 540c can be disposed third as a “top” material layer. It is understood that any number of material layers can be used to form the at least one burl 532. In someaspects, for example, the at least one burl 532 can be made from one material layer, two material layers, three material layers, four material layers, five material layers, and so on.

[0090] It can be appreciated that the aforementioned dry etching process (e.g., RIE-ICP etch) has an additional benefit when the burl is made of more than one material, as it allows in-situ measurement and detection of the material interface(s), as has been described.

[0091] In some aspects, the at least one grounding line 534 can be formed by a partial etch, for the selected time period, to second height 548 of selected portion 546 of the at least one material layer and a full etch of a remaining portion of the at least one material layer that exposes surface 536 of object 531. For example, the at least one grounding line 534 can be formed by the partial etch, for the selected time period, to second height 548 of selected portion 546 of a plurality of material layers and a full etch of a remaining portion of one or more material layers that exposes surface 536 of object 531.

[0092] For clarity of illustration, the example aspect of FIG. 5B depicts the at least one grounding line 534 as made from one material layer 540a, which is the “bottom” material layer of the three material layers 540a-540c that also forms part of the at least one burl 532. It is understood that any number of material layers can be used to form the at least one grounding line 534. For example, the at least one grounding line 534 can be made from one material layer, two material layers, three material layers, four material layers, five material layers, etc.

[0093] In some aspects, each of the plurality of material layers can include any material suitable for use in manufacturing performed by a lithographic apparatus (e.g., the manufacture of ICs). For example, each of the plurality of material layers can be a layer of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, diamond-like coating, or the like. In some aspects, each of the plurality of material layers can be made from the same material as another material layer. In some aspects, each of the plurality of material layers can be made from a different material from another material layer. Each of the plurality of material layer can be disposed on surface 536 in a single coating cycle but with corresponding parameters for each material layer.

[0094] In the example aspect shown in FIG. 5B, each of material layers 540a-540c can be made from a different material from the other ones of material layers 540a-540c. In one example, each of material layers 540a-540c can include a different chemical composition of chrome nitride. Chrome nitride can have chemical compositions of chrome and nitrogen that alter the properties and / or characteristics of the material. Accordingly, material layers 540a and 540c can have corresponding chemical compositions such that material layers 540a and 540c hardly deform, while material layer 540b can have a chemical composition such that material layer 540b is comparatively more deformable than material layers 540a and 540c.

[0095] By way of a specific example, layer 540a may comprise a Chromium Nitride CrN dense layer, layer 540b may comprise a CrN sponge layer and layer 540c may comprise a CrN top layer. These layers may be formed via a CrN sputtering process. In such an example, the at least one burl may be etched using the aforementioned RIE-ICP process such that the burl structuring step etches fully throughthe top and sponge layers 540b, 540c, to (and optionally partially into) the dense layer 540a and that the at least one grounding line is formed from the dense layer 540a.

[0096] Optionally, in such a multilayer RIE-ICP method, the same basic RIE-ICP etch process as that described above to structure the at least one burl can also be used to structure a seal around the periphery of the clamp (e.g., on both sides). The only difference is the exposed pattern (e.g., comprising a ring around the clamp periphery) and the etch depth (e.g., through the top layer and partially into the sponge layer). Alternatively, present seal forming methods may be used.

[0097] In another specific multilayer example, described in WO2022 / 268655 which is incorporated herein by reference, the material layers may comprise a multilayer laminate 20, in turn comprising a notch absorption layer 21 embedded between a top layer 22 and an adhesive layer 23.

[0098] In some aspects, FIG. 5C shows a cross-section view of another example aspect of apparatus 530, referred to as apparatus 530C. In some aspects, apparatus 530C can be an alternative aspect of apparatuses 530A and 530B as shown in and described with reference to FIGS. 5A and 5B, respectively. The elements of apparatus 530C shown in FIG. 5C may be similar to the elements of apparatuses 530A and 530B as shown in and described with reference to FIGS. 5A and 5B, respectively. Accordingly, the numbered elements previously described with regard to apparatuses 530A and 530B can have the same structure and functions in apparatus 530C and the detailed description related to those elements is incorporated in the description of apparatus 530C. In some aspects, apparatus 530C can include an object 531, at least one burl 532, and at least one grounding line 534. Specifically, apparatus 530C can include a structure of at least one burl 532 and at least one grounding line 534 formed with an etchstop layer 552 among the at least one material layer 540 on object 531.

[0099] In some aspects, etchstop layer 552 can be disposed with the at least one material layer 540 on surface 536. For example, etchstop layer 552 can be embedded within the at least one material layer 540. In this configuration, conditions in a vacuum chamber used for manufacturing the at least one material layer 540 and etchstop layer 552 can be varied to avoid cross-reactions between materials.

[0100] In some aspects, etchstop layer 552 can be disposed at second height 548 that is selected for the at least one grounding line 534. In some aspects, etchstop layer 552 can be a layer of material that is resistant to a first etchant used in the partial etch and reactive to a second etchant used in the full etch. For example, etchstop layer 552 can be formed from titanium, silicon, or the like. In this configuration, the at least one material layer 540 can be etched by the first etchant of the partial etch to second height 548 that exposes a selected portion of etchstop layer 552, thereby forming a top surface of the at least one grounding line 534. In this configuration, a remaining portion of etchstop layer 552 can be etched by the second etchant of the full etch that exposes surface 536 of object 531, thereby forming sidewalls of the at least one grounding line 534. Accordingly, etchstop layer 552 can be disposed as a material layer forming a top surface of the at least one grounding line 534 once the at least one grounding line 534 has been partially and fully etched. Due to the resistance of etchstop layer 552 to the first etchantof the partial etch, etchstop layer 552 can provide the at least one grounding line 534 with a uniform surface profile having a consistent height and a minimal PV range.

[0101] In some aspects, FIG. 5D shows a cross-section view of another example aspect of apparatus 530, referred to as apparatus 530D. In some aspects, apparatus 530D can be an alternative aspect of apparatuses 530A-530C as shown in and described with reference to FIGS. 5A-5C, respectively. The elements of apparatus 530D shown in FIG. 5D may be similar to the elements of apparatuses 530A-530C as shown in and described with reference to FIGS. 5A-5C, respectively. Accordingly, the numbered elements previously described with regard to apparatuses 530A-530C can have the same structure and functions in apparatus 530D and the detailed description related to those elements is incorporated in the description of apparatus 530D. In some aspects, apparatus 530D can include an object 531, at least one burl 532, and at least one grounding line 534. Specifically, apparatus 530D can include a structure of at least one burl 532 and at least one grounding line 534 formed with material layers that react differently depending on an etchant used in the structuring process.

[0102] In some aspects, the at least one burl 532 can be made from at least one material layer disposed at first height 542 on surface 536 of object 531. For example, the at least one burl 532 can be made from a plurality of material layers successively disposed up to first height 542 on surface 536. The term “disposed” can include similar terms, for example, “deposited,” “put down,” “placed,” “added,” “built up,” or the like.

[0103] In some aspects, the at least one burl 532 can be made from material layers that include a resistant layer 554 and a reactive layer 556. Resistant layer 554 can be a first material layer that is resistant to a first etchant used in the partial etch and reactive to a second etchant used in the full etch. Reactive layer 556 can be a second material layer reactive to the first etchant used in the partial etch. Resistant layer 554 can be disposed at second height 548 that is selected for the at least one grounding line 534 and reactive layer 556 can be disposed on resistant layer 554 up to first height 542. In this configuration, reactive layer 556 can be etched by the first etchant of the partial etch to form the at least one burl 532.

[0104] In some aspects, the at least one grounding line 534 can be made from a material layer that includes a resistant layer 554. In this configuration, reactive layer 556 can be etched by the first etchant of the partial etch to second height 548 that exposes a selected portion of resistant layer 554, thereby forming a top surface of the at least one grounding line 534. In this configuration, a remaining portion of resistant layer 554 can be etched by the second etchant of the full etch that exposes surface 536 of object 531, thereby forming sidewalls of the at least one grounding line 534. Due to the resistance of resistant layer 554 to the first etchant of the partial etch, resistant layer 554 can provide the at least one grounding line 534 with a uniform surface profile having a consistent height and a minimal PV range.

[0105] In some aspects, each of resistant layer 554 and reactive layer 556 can include any material suitable for use in manufacturing performed by a lithographic apparatus (e.g., the manufacture of ICs). For example, each of the plurality of material layers can be a layer of chrome nitride, titanium nitride,boron-doped diamond, phosphorus-doped diamond, diamond-like coating, titanium, silicon, or the like. Each of resistant layer 554 and reactive layer 556 can be disposed on surface 536 in a single coating cycle but with corresponding parameters for each material layer.

[0106] The various aspects of apparatuses 530A-530D (collectively, apparatus 530) as shown in and described with reference to FIG. 5 A-5D can offer numerous improvements over existing devices formed by existing manufacturing methods.

[0107] In some aspects, apparatus 530 (e.g., apparatus 530A and apparatus 530B) can provide an improved cohesion between the at least one burl 532 and the at least one grounding line 534. For example, the at least one burl 532 and the at least one grounding line 534 can be made from the same material. The use of the same material for the at least one burl 532 and the at least one grounding line 534 can provide a stronger cohesive force within this same material, as compared to forces between adjacent layers of different materials.

[0108] In some aspects, apparatus 530 can provide an improved structural integrity for the at least one grounding line 534 such that the at least one grounding line 534 is resistant to breakages. For example, the at least one grounding line 534 can be etched from a denser, thicker material that has reduced internal stresses as compared to a grounding line formed by an addition of a thin coating of grounding material that is used in existing devices. With reduced internal stresses, the at least one grounding line 534 is less likely to develop microfissures and / or breakages. As a result, the at least one grounding line 534 can provide more reliable grounding and reduces or eliminates the likelihood of manual repairs.

[0109] In some aspects, apparatus 530 can provide at least one burl 532 having a consistent flatness. In one example, existing devices can include multiple material layers having different thicknesses and mismatched internal stresses which may cause a corona effect for burls in existing devices. Additionally, the thin coating of grounding material that is applied to sides of the burls in the existing devices further causes a mismatch in internal stresses along the sides and may contribute to the corona effect. In contrast, apparatus 530 can use the at least one material layer 540 to form the at least one burl 532 such that there are no mismatched internal stresses at the top and sides of the at least one burl 532. Therefore, the at least one burl 532 in apparatus 530 can have a minimal or no corona effect.

[0110] FIG. 6 shows atop view of an apparatus 630 that includes a structure of burls 632 and grounding lines 634, according to some aspects. In some aspects, apparatus 630 can be an aspect of apparatuses 530A-530D as shown in and described with reference to FIGS. 5A-5D, respectively. The elements of apparatus 630 shown in FIG. 6 may be similar to the elements of apparatuses 530A-530D as shown in and described with reference to FIGS. 5A-5D, respectively. Accordingly, the like-numbered elements previously described with regard to apparatuses 530A-530D can have the same structure and functions in apparatus 630 and the detailed description related to those elements is incorporated in the description of apparatus 630. In some aspects, apparatus 630 can include an object 631, at least one burl 632, and at least one grounding line 634. It is understood that FIG. 6 merely illustrates a portion of apparatus 630and that apparatus 630 can include a plurality of burls 632 and corresponding grounding lines 634 across surface 636 of object 631.

[0111] In some aspects, at least one burl 632 can be formed on surface 636 of object 631. For clarity of illustration, the example aspect of FIG. 6 depicts two burls 632 adjacent to each other to indicate how a plurality of burls 632 can be arranged in sequence on object 631. It is understood that any number of burls 632 can be arranged on object 631, ranging from at least one burl 632 to hundreds or thousands of burls 632.

[0112] In some aspects, a surface area of each burl 632 can be any suitable shape for supporting an article such as, for example, a circular area, a polygonal area, an irregular area, or the like. In the example aspect shown in FIG. 6, the surface area of each burl 632 can be circular. In some aspects, dimensions of a surface area of each burl 632 can be any suitable size for supporting an article. For example, the surface area of each burl 632 can be hundreds of microns wide. In some aspects, adjacent ones of burls 632 can be any distance apart relative to each other. For example, adjacent ones of burls 632 can be millimeters apart.

[0113] In some aspects, at least one grounding line 634 can be formed on surface 636 of object 631. For clarity of illustration, the example aspect of FIG. 6 depicts one grounding line 634 that connects two adjacent burls 632 on object 631. It is understood that any number of grounding lines 634 can be arranged on object 631, ranging from at least one grounding line 634 to hundreds or thousands of grounding lines 634. In some aspects, adjacent ones of grounding lines 634 can be arranged in any pattern such as, for example, a web, a fan, a grid, or the like, on surface 636 of object 631. In some aspects, adjacent ones of grounding lines 634 can be any distance apart relative to each other. For example, adjacent ones of grounding lines 634 can be millimeters apart.

[0114] In some aspects, each grounding line 634 can include one or more border sections 633 and one or more connector sections 635. For example, the one or more border sections 633 and the one or more connector sections 635 of agrounding line 634 can be formed as a continuous structure. In some aspects, each border section 633 of each grounding line 634 can be configured to surround a corresponding burl 632. In some aspects, each connector section 635 of each grounding line 634 can be configured to connect the one or more border sections 633 (and therefore the corresponding burls 632) to a common ground 650. Common ground 650 can be a ground plane located outside of an operational area of object 631.

[0115] In some aspects, each border section 633 can be any suitable perimeter shape for grounding and stress distribution around the corresponding burl 632 such as, for example, an annular perimeter, a polygonal perimeter, an irregular perimeter, or the like. For example, the perimeter shape of each border section 633 can be configured to surround a shape of the corresponding burl 632. In the example aspect shown in FIG. 6, the perimeter shape of each border section 633 of grounding line 634 can be annular, thereby surrounding the circular shape of the corresponding burl 632. In some aspects, a width of each border section 633 can be any suitable size to resist a breakage in the corresponding grounding line 634.For example, the width of each border section 633 can be tens or hundreds of microns wide. For clarity of illustration, the example aspect of FIG. 6 depicts two border sections 633 adjacent to each other to indicate how a plurality of burls 632 can be surrounded by corresponding border sections of grounding line 634. It is understood that any number of border sections 633 can be arranged on object 631 that corresponds to the number of burls 632.

[0116] In some aspects, a width of each connector section 635 can be any suitable size to resist a breakage in the corresponding grounding line 634. For example, the width of each connector section 635 can be tens or hundreds of microns wide. For clarity of illustration, the example aspect of FIG. 6 depicts two connector sections 635 that connect two border sections 633 to each other and to common ground 650. In this configuration, FIG. 6 indicates how a plurality of burls 632 can be connected by connector sections 635 of grounding line 634. It is understood that any number of connector sections 635 can be arranged on object 631 to connect any corresponding number of burls 632 to common ground 650.

[0117] Example Method of Forming Burls and Grounding Lines

[0118] FIG. 7 shows a method 760 of forming burls (e.g., burls 532) and grounding lines (e.g., grounding lines 534), according to some aspects.

[0119] In some aspects, at step 762, at least one material layer (e.g., material layer 540) can be disposed at a first height (e.g., first height 542) on a surface (e.g., surface 536) of an object (e.g., object 531). In one example, the object can be a wafer clamp (e.g., wafer clamp component of substrate table WT, wafer clamp component of substrate table 421, etc.) such that the at least one material layer is disposed at the first height on the surface of the wafer clamp. In another example, the object can be a reticle clamp (e.g., reticle clamp component of support structure MT) such that the at least one material layer is disposed at the first height on the surface of the reticle clamp. The term “disposed” can include similar terms, for example, “deposited,” “put down,” “placed,” “added,” “built up,” or the like. The at least one material layer can include at least one layer of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, diamond-like coating, or the like.

[0120] In some aspects, the disposing of the at least one material layer can include successively disposing a plurality of material layers (e.g., material layers 540a-540c) up to the first height on the surface.

[0121] In some aspects, the disposing of the at least one material layer can include at least one of: (1) disposing a first material layer (e.g., material layer 540) from the surface of the object to a second height (e.g., second height 548); (2) disposing an etchstop layer (e.g., etchstop layer 552) at the second height; and (3) disposing at least a second material layer (e.g., material layer 540) from the second height to the first height.

[0122] In some aspects, the disposing of the at least one material layer can include disposing a first material layer (e.g., resistant layer 554) resistant to a first etchant used in the partially etching and reactive to a second etchant used in the fully etching. The disposing of the at least one material layercan further include disposing a second material layer (e.g., reactive layer 556) reactive to the first etchant used in the partially etching.

[0123] In some aspects, at step 764, a first mask can be positioned over a core portion (e.g., core portion 538, also referred to herein as a “central portion”) of the at least one material layer. Step 764 can further include placement of a photoresist over the at least one material layer and exposure of the photoresist at selected portions of the at least one material layer via a mask pattern. In this configuration, the first mask can cover the part of the photoresist located above the core portion so that this part of the photoresist is not exposed and therefore forms a protective layer over the core portion of the at least one material layer. In some embodiments, such as an RIE-ICP etch embodiment (e.g., to etch one or more CrN material layers), the mask may comprise a hard mask having been exposed and etched using an initial mask in an initial hard mask structuring step.

[0124] In some aspects, at step 766, a selected portion (e.g., selected portion 546) of the at least one material layer adjacent to the core portion can be partially etched, for a selected time period, until the selected portion is at a second height (e.g., second height 548) that is less than the first height such that a burl (e.g., burl 532) is formed from the core portion at the first height. In some aspects, the partially etching the selected portion can include liquid etching, reactive ion etching, or laser machining the selected portion to the second height. This partial etch step may use an RIE-ICP etching process, and optionally may be followed by a (e.g., RIE-ICP) mask removal etch step.

[0125] In some aspects, at step 768, a second mask can be positioned over the core portion and the selected portion. Step 768 can further include placement of a photoresist over the at least one material layer and exposure of the photoresist at remaining portions of the at least one material layer via a mask pattern. In this configuration, the use of the second mask can cover the core portion and the selected portion such that the photoresist is not exposed and therefore forms a protective layer over the core portion and the selected portion of the at least one material layer.

[0126] In some aspects, at step 770, a remaining portion of the at least one material layer can be fully etched to expose the surface of the object such that at least one grounding line (e.g., grounding line 534) is formed from the selected portion at the second height. Again, this full etch step may use an RIE-ICP etching process.

[0127] In some aspects, method 760 can further include removing the photoresist from the at least one burl and the at least one grounding line after the full etch.

[0128] In some aspects, method 760 can further include polishing the at least one material layer before positioning the first mask over the core portion.

[0129] The method steps of FIG. 7 can be performed in any conceivable order and it is not required that all steps be performed. Moreover, the method steps of FIG. 7 described above merely reflect an example of steps and are not limiting. That is, further method steps and functions are envisaged based on aspects described in reference to FIGS. 1-6 above and FIGS. 8A-8F below.

[0130] FIGS. 8A-8F show cross-section views of structures formed at corresponding method steps 762-770 described in FIG. 7, according to some aspects. The steps 862-870 shown in FIGS. 8A-8F may be similar to the steps 762-770 as shown in and described with reference to FIG. 7. Accordingly, the numbered elements previously described with regard to steps 762-770 can have the same structure and functions in steps 862-871 and the detailed description related to those elements is incorporated in the description of steps 862-870. In some aspects, FIGS. 8A-8F show cross-section views of structural components that form the apparatus 830 shown in FIG. 8F. In some aspects, apparatus 830 can be an alternative aspect of apparatuses 530 and 630 as shown in and described with reference to FIGS. 5A-5D and 6, respectively. The elements of apparatus 830 shown in FIGS. 8A-8F may be similar to the elements of apparatuses 530 and 630 as shown in and described with reference to FIGS. 5A-5D and 6, respectively. Accordingly, the numbered elements previously described with regard to apparatuses 530 and 630 can have the same structure and functions in apparatus 830 and the detailed description related to those elements is incorporated in the description of apparatus 830.

[0131] In some aspects, as shown in FIG. 8A, at step 862, at least one material layer 840 can be disposed at a first height 842 on a surface 836 of an object 831. The type of the at least one material layer 840 and first height 842 can be selected based on a desired application of the completed apparatus. A surface of the at least one material layer 840 can be cleaned and / or polished to remove any contamination or deformities before any further structural processing in steps 864-871.

[0132] In some aspects, as shown in FIG. 8B, at step 864, a first mask 872 can be positioned over a core portion 838 of the at least one material layer 840. Step 864 can further include placement of a photoresist 874 over the at least one material layer 840. Step 864 can further include the use of an exposure device 875 configured to expose photoresist 874 with radiation such as, for example, EUV radiation. Due to the positioning and / or patterning of first mask 872, photoresist 874 can be exposed by exposure device 875 at locations other than core portion 838 of the at least one material layer 840. In this configuration, first mask 872 can cover the part of photoresist 874 located above core portion 838 so that this part of photoresist 874 is not exposed and therefore forms a protective layer over core portion 838 of the at least one material layer 840. The exposed parts of photoresist 874 can become soluble from exposure and can be removed from the at least one material layer 840.

[0133] In some aspects, as shown in FIG. 8C, at step 866, a selected portion 846 of the at least one material layer 840 adjacent to core portion 838 can be partially etched, for a selected time period, until selected portion 846 is at a second height 848 that is less than first height 842 such that a burl 832 is formed from core portion 838 at first height 842. Selected portion 846 can be partially etched by etching device 876, which is configured to perform at least one of liquid etching, reactive ion etching, or laser machining. Etching device 876 can be coupled to or include a controller 877 configured to initiate and stop the etching according to a selected time period. Controller 877 can be further configured to adjust the time period of the etching according to a selected design for the resulting structure.

[0134] In some aspects, as shown in FIG. 8D, at step 868, a second mask 878 can be positioned over core portion 832 and selected portion 846. Step 868 can further include placement of a photoresist 874 over the at least one material layer 840. Step 868 can further include the use of exposure device 875, which is configured to expose photoresist 874 with radiation such as, for example, EUV radiation. Due to the positioning and / or patterning of second mask 878, photoresist 874 can be exposed by exposure device 875 at a remaining portion 880 of the at least one material layer 840. In this configuration, second mask 878 can cover the part of photoresist 874 located above core portion 838 and selected portion 846 so that this part of photoresist 874 is not exposed and therefore forms a protective layer over core portion 838 and selected portion 846 of the at least one material layer 840. The exposed parts of photoresist 874 can become soluble from exposure and can be removed from the at least one material layer 840.

[0135] In some aspects, as shown in FIG. 8E, at step 870, a remaining portion 880 of the at least one material layer 840 can be fully etched to expose surface 836 of object 831 such that at least one grounding line 834 is formed from selected portion 846 at second height 848. Remaining portion 880 can be fully etched by etching device 876, which is configured to perform at least one of liquid etching, reactive ion etching, or laser machining. Etching device 876 can be coupled to or include a controller 877 configured to initiate and stop the etching according to a selected time period. Controller 877 can be further configured to adjust the time period of the etching according to a selected design for the resulting structure. For the full etching, controller 877 can allow etching device 876 to etch until remaining portion 880 of the at least one material layer 840 has been completely removed from surface 836.

[0136] In some aspects, as shown in FIG. 8F, at step 871, photoresist 874 from steps 874-870 can be removed from the at least one material layer 840. Specifically, photoresist 874 can be removed from the at least one burl 832 and the at least one grounding line 834 formed after the full etch of step 870. Photoresist 874 can be removed via a chemical solution and / or mechanical stripping. Once photoresist 874 has been removed, an apparatus 830 can be considered complete. In some aspects, apparatus 830 can include object 831, the at least one burl 832, and the at least one grounding line 834.

[0137] FIG. 7 and FIGS. 8A-8F illustrate that the described structuring method (e.g., method 760) can offer numerous improvements over existing manufacturing methods. For example, the described structuring method can include only one coating step (e.g., step 762, step 862, etc.) in contrast to the multiple coating steps of existing manufacturing methods. Existing manufacturing methods may move components back and forth between separate locations to perform alternating coating processes and etching processes. In contrast, the described structuring method can perform a coating step followed by etching steps. By performing a complete coating of the at least one material layer at the beginning of the described structuring method, the described structuring method can save time, money, and logistics as compared to existing manufacturing methods.

[0138] Various example embodiments of the subject disclosure include the following numbered clauses:1. A method of forming burls and grounding lines, the method comprising:disposing at least one material layer at a first height on a surface of an object; positioning a first mask over a core portion of the at least one material layer;partially etching, for a selected time period, a selected portion of the at least one material layer adjacent to the core portion until the selected portion is at a second height that is less than the first height such that at least one burl is formed from the core portion at the first height;positioning a second mask over the core portion and the selected portion; andfully etching a remaining portion of the at least one material layer to expose the surface of the object such that at least one grounding line is formed from the selected portion at the second height.2. The method of clause 1, wherein the disposing the at least one material layer comprises disposing a single layer of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, or diamond-like coating.3. The method of clause 1, wherein the disposing the at least one material layer comprises disposing a plurality of layers of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, diamond-like coating, or combinations thereof.4. The method of clause 1, 2, or 3, wherein the disposing the at least one material layer comprises: disposing a first material layer from the surface of the object to the second height;disposing an etchstop layer at the second height; anddisposing at least a second material layer from the second height to the first height.5. The method of any preceding clause, wherein the disposing the at least one material layer comprises:disposing a first material layer resistant to a first etchant used in the partially etching and reactive to a second etchant used in the fully etching; anddisposing a second material layer reactive to the first etchant used in the partially etching.6. The method of any preceding clause, wherein the partially etching the selected portion comprises liquid etching, reactive ion etching, or laser machining the selected portion to the second height.7. The method of any preceding clause wherein the partially etching the selected portion comprises reactive ion etching combined with inductively coupled plasma.8. The method of clause 7, wherein the first mask comprises a hard mask.9. The method of clause 8, wherein the step of positioning a first mask comprises: positioning an initial mask onto a hard mask layer; andetching the hard mask layer at the selected portion to form the hard mask.10. The method of clause 9, wherein the step of etching the hard mask layer comprises reactive ion etching combined with inductively coupled plasma.11. The method of clause 8, 9, or 10, wherein the partially etching step comprises a burl structuring etch using a first etchant to etch the selected portion of the at least one material layer; and at least one hard mask etch step using a second etchant to remove the hard mask material.12. The method of clause 11, wherein the at least one hard mask etch step comprises a hard mask structuring step to form the hard mask prior to partially etching step; and a hard mask removal step to remove the hard mask from the core portion after the partially etching step.13. The method of any preceding clause, wherein the fully etching a remaining portion comprises reactive ion etching combined with inductively coupled plasma.14. The method of any preceding clause, wherein the at least one material layer comprises a dense chromium nitride layer, a sponge chromium nitride layer and a top chromium nitride layer.15. The method of any preceding clause, comprising controlling either or both of the partially etching and / or fully etching steps by:illuminating a surface being etched;detecting resultant reflected radiation from the surface being etched;detecting one or more interfaces between different layers of the at least one material layer from the resultant reflected radiation; andcontrolling the etch based on the detected one or more interfaces.16. The method of any preceding clause, further comprising polishing the at least one material layer before positioning the first mask over the core portion.17. The method of any preceding clause, wherein the disposing the at least one material layer to the first height on the surface of the object comprises disposing the at least one material layer to the first height on the surface of a wafer clamp.18. The method of any preceding clause, wherein the disposing the at least one material layer to the first height on the surface of the object comprises disposing the at least one material layer to the first height on the surface of a reticle clamp.19. An apparatus comprising:an object comprising a surface;at least one burl comprising at least one material layer disposed at a first height on the surface, each of the at least one burl formed by a partial etch, for a selected time period, to a second height of a selected portion of the at least one material layer adjacent to a corresponding core portion of the at least one material layer; andat least one grounding line formed by the partial etch, for the selected time period, to the second height of the selected portion and a full etch of a remaining portion of the at least one material layer that exposes the surface;wherein the at least one grounding line is configured to connect the at least one burl to a common ground; andwherein the second height is less than the first height.20. The apparatus of clause 19, wherein the at least one material layer comprises a single layer of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, or diamond-like coating.21. The apparatus of clause 19, wherein the at least one material layer comprises a plurality of layers of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, diamondlike coating, or combinations thereof.22. The apparatus of any of clauses 19 to 21, further comprising an etchstop layer disposed on the at least one grounding line at the second height.23. The apparatus of any of clauses 19 to 22, wherein the at least one material layer comprises: a first material layer resistant to a first etchant used in the partial etch and reactive to a second etchant used in the full etch; anda second material layer reactive to the first etchant used in the partial etch.24. The apparatus of any of clauses 19 to 23, wherein the partial etch comprises a liquid etch, a reactive ion etch, or a laser machining process of the selected portion to the second height.25. The apparatus of any of clauses 19 to 24, wherein the partial etch comprises reactive ion etching combined with inductively coupled plasma.26. The apparatus of any of clauses 19 to 25, wherein the full etch comprises reactive ion etching combined with inductively coupled plasma.27. The apparatus of any of clauses 19 to 26, wherein the at least one material layer comprises a dense chromium nitride layer, a sponge chromium nitride layer and a top chromium nitride layer. 28. The apparatus of any of clauses 19 to 27, wherein the at least one burl comprises a polished surface.29. The apparatus of any of clauses 19 to 28, wherein the object comprises a wafer clamp.30. The apparatus of any of clauses 19 to 28, wherein the object comprises a reticle clamp.31. A lithographic system comprising:an illumination system configured to condition a radiation beam;a patterning system configured to impart a pattern onto the radiation beam to form a patterned beam; a projection system configured to project the patterned beam onto a substrate; andat least one clamp apparatus comprising:an object comprising a surface;at least one burl comprising at least one material layer disposed at a first height on the surface, each of the at least one burl formed by a partial etch, for a selected time period, to a second height of a selected portion of the at least one material layer adjacent to a corresponding core portion of the at least one material layer; andat least one grounding line formed by the partial etch, for the selected time period, to the second height of the selected portion and a full etch of a remaining portion of the at least one material layer that exposes the surface;wherein the at least one grounding line is configured to connect the at least one burl to a common ground; andwherein the second height is less than the first height.32. The lithographic system of clause 31, wherein the at least one material layer comprises a single layer of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, or diamond-like coating.33. The lithographic system of clause 31, wherein the at least one material layer comprises a plurality of layers of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, diamond-like coating, or combinations thereof.34. The lithographic system of any of clauses 31 to 33, further comprising an etchstop layer disposed on the at least one grounding line at the second height.35. The lithographic system of any of clauses 31 to 34, wherein the at least one material layer comprises:a first material layer resistant to a first etchant used in the partial etch and reactive to a second etchant used in the full etch; anda second material layer reactive to the first etchant used in the partial etch.36. The lithographic system of any of clauses 31 to 35, wherein the partial etch comprises a liquid etch, a reactive ion etch, or a laser machining process of the selected portion to the second height. 37. The lithographic system of any of clauses 31 to 36, wherein the partial etch comprises reactive ion etching combined with inductively coupled plasma.38. The lithographic system of any of clauses 31 to 37, wherein the full etch comprises reactive ion etching combined with inductively coupled plasma.39. The lithographic system of any of clauses 31 to 38, wherein the at least one material layer comprises a dense chromium nitride layer, a sponge chromium nitride layer and atop chromium nitride layer.40. The lithographic system of any of clauses 31 to 39, wherein the at least one burl comprises a polished surface.41. The lithographic system of any of clauses 31 to 40, wherein the object comprises a wafer clamp configured to support the substrate.42. The lithographic system of any of clauses 31 to 41, wherein the object comprises a reticle clamp configured to support a reticle of the patterning system.

[0139] The terms “radiation,” “beam,” “light,” “illumination,” or the like can be used herein to refer to one or more types of electromagnetic radiation, for example, ultraviolet (UV) radiation (for example, having a wavelength X of 365, 248, 193, 157, or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (for example, having a wavelength in the range of 5-100 nm such as, for example, 13.5 nm), or hard X-ray working at less than 5 nm, as well as particle beams, such as ion beams or electron beams. Generally, radiation having wavelengths between about 400 to about 700 nm is considered visibleradiation; radiation having wavelengths between about 780-3000 nm (or larger) is considered IR radiation. UV refers to radiation with wavelengths of approximately 100-400 nm. Within lithography, the term “UV” also applies to the wavelengths that can be produced by a mercury discharge lamp: G-line 436 nm, H-line 405 nm, and / or I-line 365 nm. Vacuum UV, or VUV (i.e., UV absorbed by gas), refers to radiation having a wavelength of approximately 100-200 nm. Deep UV (DUV) generally refers to radiation having wavelengths ranging from 126 nm to 428 nm, and in some aspects, an excimer laser can generate DUV radiation used within a lithographic apparatus. It should be appreciated that radiation having a wavelength in the range of, for example, 5-20 nm relates to radiation with a certain wavelength band, of which at least part is in the range of 5-20 nm.

[0140] Although some aspects of the present disclosure are described in the context of lithographic apparatuses in the manufacture of ICs, it should be understood that lithographic apparatuses described herein can be used in other applications, for example, in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, UCDs, thin-film magnetic heads, etc. Those skilled in the art will appreciate that, in the context of such alternative applications, any use of the terms “wafer” or “die” herein can be considered as specific examples of the more general terms “substrate” or “target portion,” respectively. A substrate can be processed before or after exposure in, for example, a track unit (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) and / or a metrology unit. Where applicable, aspects disclosed herein can be applied to such and other substrate processing tools. Furthermore, a substrate can be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein can also refer to a substrate that already contains multiple processed layers.

[0141] The terms “inspection apparatus,” “metrology system,” or the like can be used herein to refer to a device used for measuring a property of a structure (e.g., overlay sensor, critical dimension sensor, or the like), a device or system used in a lithographic apparatus to inspect an alignment of a wafer (e.g., alignment sensor), or the like.

[0142] Furthermore, although some aspects of the present disclosure are described in the context of optical lithography, it should be understood that aspects of the present disclosure are not limited to optical lithography. For example, in imprint lithography, a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device can be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

[0143] It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

[0144] 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 thesefunctional 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.

[0145] 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

1. CLAIMS1. A method of forming burls and grounding lines, the method comprising:disposing at least one material layer at a first height on a surface of an object; positioning a first mask over a core portion of the at least one material layer;partially etching, for a selected time period, a selected portion of the at least one material layer adjacent to the core portion until the selected portion is at a second height that is less than the first height such that at least one burl is formed from the core portion at the first height;positioning a second mask over the core portion and the selected portion; andfully etching a remaining portion of the at least one material layer to expose the surface of the object such that at least one grounding line is formed from the selected portion at the second height.

2. The method of claim 1, wherein the disposing the at least one material layer comprises disposing a single layer of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, or diamond-like coating.

3. The method of claim 1, wherein the disposing the at least one material layer comprises disposing a plurality of layers of chrome nitride, titanium nitride, boron-doped diamond, phosphorus-doped diamond, diamond-like coating, or combinations thereof.

4. The method of any preceding claim, wherein the disposing the at least one material layer comprises:disposing a first material layer from the surface of the object to the second height;disposing an etchstop layer at the second height; anddisposing at least a second material layer from the second height to the first height.

5. The method of any preceding claim, wherein the disposing the at least one material layer comprises:disposing a first material layer resistant to a first etchant used in the partially etching and reactive to a second etchant used in the fully etching; anddisposing a second material layer reactive to the first etchant used in the partially etching.

6. The method of any preceding claim, wherein the partially etching the selected portion comprises liquid etching, reactive ion etching, or laser machining the selected portion to the second height.

7. The method of any preceding claim wherein one or both of: the step of partially etching the selected portion and / or fully etching a remaining portion comprises reactive ion etching combined with inductively coupled plasma.

8. The method of claim 7, wherein the first mask comprises a hard mask; and wherein the step of positioning a first mask comprises:positioning an initial mask onto a hard mask layer; andetching the hard mask layer at the selected portion to form the hard mask.

9. The method of claim 8, wherein the partially etching step comprises a burl structuring etch using a first etchant to etch the selected portion of the at least one material layer; and at least one hard mask etch step using a second etchant to remove the hard mask material.

10. The method of any preceding claim, comprising controlling either or both of the partially etching and / or fully etching steps by:illuminating a surface being etched;detecting resultant reflected radiation from the surface being etched;detecting one or more interfaces between different layers of the at least one material layer from the resultant reflected radiation; andcontrolling the etch based on the detected one or more interfaces.

11. The method of any preceding claim, further comprising polishing the at least one material layer before positioning the first mask over the core portion.

12. The method of any preceding claim, wherein the disposing the at least one material layer to the first height on the surface of the object comprises disposing the at least one material layer to the first height on the surface of a wafer clamp.

13. The method of any preceding claim, wherein the disposing the at least one material layer to the first height on the surface of the object comprises disposing the at least one material layer to the first height on the surface of a reticle clamp.

14. An apparatus comprising:an object comprising a surface having at least one material layer disposed thereon, the at least one material layer comprising:at least one burl, each at least one burl comprising a first height; andat least one grounding line, each at least one grounding line comprising a second height, the second height being less than the first height;wherein the at least one burl and the at least one grounding line is formed according to the method of any preceding claim.

15. A lithographic system comprising:an illumination system configured to condition a radiation beam;a patterning system configured to impart a pattern onto the radiation beam to form a patterned beam; a projection system configured to project the patterned beam onto a substrate; andat least one clamp apparatus comprising the apparatus of claim 14.

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