Method of refurbishing substrate support

Abstract

A method of refurbishing a substrate support, the substrate support comprising: a first surface configured to support a substrate; and a second surface opposite to the first surface. The method includes depositing a material on the second surface to form a coating that increases a thickness of the substrate support; and removing material from the first surface.

Description

Cross-reference to related applications

[0001] This application claims priority to European Patent Application No. 23202227.7, filed on October 6, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to a method for refurbishing a substrate support and the substrate support thereby refurbished. The method may be applied to a substrate support that has already been used by a photolithography apparatus. This photolithography apparatus may be an exposure apparatus for exposing a substrate or a measurement apparatus for inspecting a substrate. The method may be applied during the manufacturing process of the substrate support. Background Technology

[0003] A lithography apparatus is a machine configured to apply a desired pattern to a substrate. For example, a lithography apparatus can be used in the manufacture of integrated circuits (ICs). For instance, a lithography apparatus may project a pattern (also commonly referred to as a “design layout” or “design”) from a patterning device (such as a mask) onto a layer of radiation-sensitive material (such as a photoresist) provided on a substrate (such as a wafer).

[0004] For decades, as semiconductor manufacturing processes have continued to advance, the size of circuit elements has steadily decreased, while the number of functional components (such as transistors) in each device has steadily increased, following a trend commonly known as "Moore's Law." To keep pace with Moore's Law, the semiconductor industry is working to develop technologies that can produce continuously shrinking features. To project patterns onto a substrate, photolithography apparatuses may use electromagnetic radiation. The wavelength of this radiation determines the minimum feature size that can be patterned on the substrate. Typical wavelengths currently used are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Photolithography apparatuses using extreme ultraviolet (EUV) radiation (with wavelengths in the range of 4 nm to 20 nm, such as 6.7 nm or 13.5 nm) may be used to form even smaller features on the substrate than those using radiation with a wavelength of, for example, 193 nm.

[0005] During pattern projection or inspection within a photolithography apparatus, a substrate support is typically used to hold the substrate. Specifically, the substrate is supported by a first surface of the substrate support. After repeated use, wear may occur at the first surface of the substrate support, rendering it unsuitable for further use. The substrate can be repaired or refurbished for further use. A known method for refurbishing a substrate support is to remove worn material by removing existing material, which results in a reduction in the thickness of the substrate support. To maintain or restore flatness, material may also be removed from non-wear areas adjacent to the worn material.

[0006] Photolithography apparatuses are highly sensitive to the thickness of the substrate support. After multiple (e.g., three) refurbishments, the thickness of the support stage may decrease, resulting in subsequent refurbishments of the substrate support becoming too thin and incompatible with the photolithography apparatus (e.g., an exposure unit). Therefore, known methods for refurbishing substrate supports lead to their eventual obsolescence after a limited number of refurbishments.

[0007] It may be desirable to provide a device that avoids or mitigates one or more problems associated with the prior art. Summary of the Invention

[0008] According to a first aspect of the present invention, the present invention provides a method for refurbishing a substrate support, the method comprising: a first surface configured to support a substrate; and a second surface opposite to the first surface; the method comprising: depositing material on the second surface to form a coating that increases the thickness of the substrate support; and removing material from the first surface.

[0009] Advantageously, the deposition of material on the second surface compensates for the material removed from the first surface, thereby restoring the thickness of the substrate support so that it can be further used. Deposition of material on the first surface is difficult due to stringent requirements for surface flatness and finish.

[0010] After the material is deposited on the second surface, it may be removed from the first surface.

[0011] The method may also include depositing material on the first surface to form a further coating that increases the thickness of the substrate support.

[0012] The coating thickness may be at least 1 μm.

[0013] The coating thickness may be at least 3 μm.

[0014] The coating thickness can reach up to 300 μm.

[0015] The second surface may be partially defined by protrusions configured as support members for the substrate.

[0016] The first surface may also be partially defined by protrusions configured to support the substrate.

[0017] The material may be selectively deposited on the protrusions on the second surface.

[0018] The material may be uniformly deposited on the second surface.

[0019] The method may also include a portion that selectively reduces the coating.

[0020] Removing material from the first surface may include fine grinding of the first surface.

[0021] The method may include depositing a diamond-like carbon coating, a chromium nitride coating, or a diamond coating on at least a portion of the first surface.

[0022] The thickness of the deposited coating may reach up to about 1000 nm.

[0023] The method may involve depositing a carbon-based coating on at least a portion of a first surface.

[0024] The method may involve depositing a wear-resistant material having a hardness greater than 6 GPa onto at least a portion of a first surface. The wear-resistant material may have a hardness greater than 20 GPa.

[0025] The method may also include finely grinding the coating.

[0026] The material deposited on the second surface to form a coating may include the same material as the second surface of the substrate support.

[0027] The material deposited on the second surface to form a coating may be silicon carbide.

[0028] Advantageously, silicon carbide adheres well to the second surface and has high polishability.

[0029] The material may be silicon dioxide or silicon nitride.

[0030] The method may involve depositing a ceramic coating with a coefficient of thermal expansion that is as high as that of silicon.

[0031] Materials may be deposited via physical vapor deposition.

[0032] Materials may be deposited via sputter deposition.

[0033] Sputtering deposition can be performed at low temperatures, reducing thermal stress in the substrate support.

[0034] Materials may be deposited via chemical vapor deposition.

[0035] The method may also include planarizing the first surface by ion beam shaping or by reactive ion etching after depositing the wear-resistant material.

[0036] According to a second aspect of the invention, a substrate support refurbished according to the disclosed method is provided.

[0037] The substrate support may be a refurbished substrate support. Attached Figure Description

[0038] Embodiments of the present invention will be described below by way of example only, with reference to the accompanying schematic diagrams:

[0039] Figure 1 A schematic overview of the photolithography apparatus is shown;

[0040] Figure 2 Showing through Figure 1 A schematic cross-sectional view of a portion of the substrate support, positioner, and substrate shown;

[0041] Figure 3 A method according to an embodiment of the present disclosure is shown;

[0042] Figure 4A A schematic cross-sectional view is shown through the substrate support already in use;

[0043] Figure 4B Showing through Figure 4A A schematic cross-sectional view of the substrate support shown after material removal;

[0044] Figure 4C Showing through Figure 4A and Figure 4B A schematic cross-sectional view of the substrate support in a refurbished state;

[0045] Figure 5A A schematic cross-sectional view is shown through an existing substrate support with a thickness less than the minimum thickness.

[0046] Figure 5B Showing through Figure 5A A schematic cross-sectional view of the substrate support shown after material deposition;

[0047] Figure 5C Showing through Figure 5A and Figure 5B A schematic cross-sectional view of the substrate support shown after material removal; and

[0048] Figure 5D Showing through Figures 5A to 5C A schematic cross-sectional view of the substrate support shown in another refurbished state; Detailed Implementation

[0049] In the current document, the terms “radiation” and “beam” are used to cover all types of electromagnetic radiation, including deep ultraviolet radiation (DUV) (e.g., with wavelengths of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., with wavelengths in the range of about 5 nm to 100 nm).

[0050] The terms “mask,” “mask,” or “patterning apparatus” as used herein may be interpreted broadly to refer to a general patterning apparatus that may be used to impart a patterned cross-section to an incident radiation beam, corresponding to a pattern to be created in a target portion of a substrate. The term “optical valve” may also be used in this context. Examples of other such patterning apparatuses, besides classic masks (transmissive or reflective, binary, phase-shifting, hybrid, etc.), include programmable mirror arrays and programmable LCD arrays.

[0051] Figure 1 A lithography apparatus LA is schematically illustrated. The lithography apparatus LA includes: an irradiation system (also called an irradiator) IL configured to modulate a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation); a mask support (e.g., a mask stage) MT configured to support a patterning apparatus (e.g., a mask) MA and connected to a first locator PM configured to precisely position the patterning apparatus MA according to specific parameters; a substrate support (e.g., a wafer stage) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second locator PW configured to precisely position the substrate support according to specific parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted by the radiation beam B by the patterning apparatus MA onto a target portion C (e.g., including one or more dies) of the substrate W.

[0052] In operation, the irradiation system IL receives a radiation beam from the radiation source SO, for example via the beam delivery system BD. The irradiation system IL may include multiple types of optical components for guiding, shaping, and / or controlling the radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof. The irradiator IL may be used to adjust the radiation beam B to have a desired spatial and angular intensity distribution in the cross-section of the plane in which the patterning device MA is located.

[0053] The term "projection system" (PS) as used herein should be interpreted broadly to encompass multiple types of projection systems, including refractive, reflective, catadioptric, variable, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, adapted to the type of exposure radiation used and / or other factors such as immersion or vacuum environments. Any term used herein, "projection lens," may be considered equivalent to the more general term "projection system" (PS).

[0054] A lithography apparatus LA can be of the type in which a portion of the substrate is covered by a liquid (e.g., water) with a relatively high refractive index to fill the space between the projection system PS and the substrate W—this is also known as immersion lithography. More information on immersion technology can be found in US6952253, which is incorporated herein by reference.

[0055] The lithography apparatus LA may also be of the type with two or more substrate supports WT (also known as "dual stage"). In such a "multi-stage" machine, the substrate supports WT may be used in parallel, and / or subsequent exposure preparation steps may be performed on a substrate W located on one of the substrate supports WT while another substrate W located on the other substrate support WT is used to expose a pattern on that other substrate.

[0056] In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is arranged to hold sensors and / or cleaning devices. The sensors may be arranged to measure characteristics of the projection system PS or the radiation beam B. The measurement stage may hold multiple sensors. The cleaning devices may be arranged to clean a part of the lithography apparatus, such as part of the projection system PS or part of a system providing immersion liquid. The measurement stage may move below the projection system PS as the substrate support WT moves away from the projection system PS.

[0057] In operation, a radiation beam B is incident on a patterning apparatus MA (e.g., a mask) held on a mask support MT and patterned by a pattern (design layout) present on the patterning apparatus MA. After passing through the mask MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of a second positioner PW and a position measurement system IF, the substrate support WT can be precisely moved, for example, to position different target portions C along the path of the radiation beam B at the focused and aligned positions. Similarly, a first positioner PM and possibly another position sensor (not shown in the image)... Figure 1 (As explicitly shown in the diagram) This may be used to position the patterning apparatus MA relative to the path of the radiation beam B. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 may be used to align the patterning apparatus MA and the substrate W. Although the substrate alignment marks P1, P2 in the diagram occupy dedicated target portions, they may also be located in the space between target portions. When the substrate alignment marks P1, P2 are located between target portions C, they are referred to as scribing alignment marks.

[0058] To illustrate this invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes: the x-axis, the y-axis, and the z-axis. Any one of the three axes is orthogonal to the other two. The x-axis and y-axis define the horizontal plane, while the z-axis lies in the vertical direction. The Cartesian coordinate system is not intended to limit the invention but is merely illustrative.

[0059] In the following description, there may be multiple instances that have substantially the same characteristics. (See appendix.) Figure 2-5D For clarity, only a single instance of each feature is labeled.

[0060] Figure 2 The schematic illustration shows portions of a known substrate support WT and a second positioner PW that hold a substrate W. The substrate support WT includes a first surface 4 configured to support the substrate W and a second surface 6 opposite to the first surface.

[0061] The first surface 4 is partially defined by protrusions including first protrusions 8 configured to support a substrate W and first vacuum seals 16 configured to create a vacuum between the substrate W and the substrate support WT. Each of the first protrusions 8 includes a distal portion 9 and a proximal portion 10. Each of the first vacuum seals 16 includes a distal portion 18 and a proximal portion 19. The proximal portions 10 of the first protrusions 8 and 19 of the first vacuum seals 16 abut the body 2 of the substrate support WT. The distal portion 9 of the first protrusion 8 is configured to directly contact the substrate (e.g., the substrate W).

[0062] The distal portion 9 of the first protrusion 8 and the distal portion 18 of the first vacuum seal 16 include a top material layer or coating 15. Coating 15 may comprise diamond-like carbon (DLC). For example, coating 15 may comprise sp3 hybrid carbon with a carbon content greater than 90%. In an alternative example, coating 15 may be substantially composed of chromium nitride (CrN). In another alternative example, coating 15 may comprise diamond, such as single-crystal diamond or polycrystalline diamond. In some embodiments, the thickness of coating 15 may reach up to about 1000 nm. In some examples, the thickness of coating 15 may be about 500 nm.

[0063] The first vacuum seal 16 protrudes less from the body 2 than the first protrusion 8. In one example, the first protrusion 8 may protrude further than the first vacuum seal 16 by about 1 μm to 10 μm in the z-direction. In another example, the first protrusion 8 may protrude further than the first vacuum seal 16 by about 10 μm to 25 μm in the z-direction.

[0064] The second surface 6 is defined by a protrusion comprising: a second protrusion 12 configured to support a substrate support WT on a second locator PW; and a second vacuum seal 17 configured to create a vacuum between the second locator PW and the substrate support WT. Each of the second protrusions 12 includes a distal portion 13 and a proximal portion 14. The proximal portion 14 of the second protrusion 12 abuts the body 2 of the substrate support WT. The distal portion 13 of the second protrusion 12 is configured to directly contact the second locator PW. The second vacuum seal 17 protrudes less from the body 2 than the second protrusion 12.

[0065] Reference Figure 2In the described embodiment of the substrate support WT, the material layer or coating provided on the first protrusion 8 and the first vacuum seal 16 is not provided on the second protrusion 12 and the second vacuum seal 17. In an alternative embodiment, a similar or identical material layer or coating (e.g., a coating including DLC, chromium nitride, or diamond) may be provided on at least a portion of the second surface 6. To compensate for the stress caused by the coating 15 at the first surface 4, it may be desirable to provide a coating at the second surface 6.

[0066] According to another embodiment, the second protrusion 12 and / or the second vacuum seal 17 are provided with a material layer or coating. The material layer or coating provided at the second protrusion 12 and / or the second vacuum seal 17 is the same material as the material layer or coating provided at the first protrusion 8 and the first vacuum seal 16.

[0067] In use, the substrate support is configured to create a region below ambient pressure (i.e., a vacuum) between the substrate W and the first surface 4 and between the second positioner PW and the second surface 6. When the substrate W is held and connected to the second positioner PW, the first vacuum seal 16 and the second vacuum seal 17 are configured to define a contraction structure to prevent free leakage of gas from the environment surrounding the substrate support WT into the region between the substrate W and the first surface 4 and the region between the second positioner PW and the second surface 6, thereby achieving more efficient vacuum generation.

[0068] The pressure difference between the surrounding environment and the area with lower pressure than the surrounding environment can generate a clamping force (approximately perpendicular to the plane where the substrate W and the second positioner PW are located), pressing the substrate W and the second positioner PW against the substrate support.

[0069] The substrate support WT using the vacuum clamping method may also be called a vacuum clamp.

[0070] Alternatively, the substrate W may also be electrostatically clamped to a substrate support. The substrate support WT may include an electrode layer arranged to provide electrostatic forces, such as electrostatic clamping forces. Electrostatic clamping of the substrate may be applied in a low-pressure (e.g., vacuum) environment. The substrate support WT utilizing electrostatic clamping may also be referred to as an electrostatic clamp. These electrostatic clamps may not include vacuum seals 16, 17.

[0071] Figure 2 (as well as Figure 3 Figure 5 shows a schematic illustration of the substrate support WT, illustrating a limited number of protrusions 8, 12. While those skilled in the art will understand that the substrate support WT comprises hundreds or thousands of protrusions 8, 12 configured to support the substrate, this limited number is for clarity only and is not intended to limit the scope of the invention. This description also applies to vacuum seals 16, 17.

[0072] Figure 3 The illustration schematically depicts a method 100 for using and refurbishing a substrate support WT according to an embodiment of the present disclosure.

[0073] In step S1, a substrate support WT is used in the lithography apparatus LA. After being used to hold multiple substrates, the substrate support WT is no longer suitable for further use in the lithography apparatus due to wear on the first surface 4. Specifically, the distal portion 9 of the first protrusion 8 and the first vacuum seal 16 may wear due to direct contact with multiple substrates.

[0074] In step S2, it is determined whether the used substrate support WT is suitable for refurbishment. This determination may include checking the thickness of the substrate support WT (as determined by...). Figures 4A to 4C (The dimension T is indicated). If the thickness of the substrate support is greater than the minimum thickness, the method proceeds to step S3.

[0075] In step S3, material is removed from the first surface 4. Removing material from the first surface 4 includes fine grinding of the first surface 4. This is done separately on... Figure 4A and Figure 4B The diagram schematically shows the substrate support WT before and after fine grinding. Fine grinding may also be referred to as polishing or grinding. Fine grinding removes the worn portions 22 of the first protrusion 8 and the first vacuum seal 16 (which may include coating 15). Figure 4A and Figure 4B (shown as dashed lines in the middle).

[0076] The thickness of the removed wear portion 22 may be several micrometers. In some cases, 1 μm or more of material may be removed. For example, at least 3 μm of material may be removed to ensure complete removal of the wear portion 22. In this case, there is a risk that some wear portion may not be completely removed.

[0077] In step S4, a new coating 15 is deposited at the distal portion 9 of the first protrusion 8 and the distal portion 18 of the first vacuum seal 16 (see...). Figure 4C This produces a refurbished substrate support WT suitable for reuse in the photolithography apparatus LA in step S1. The thickness of the new coating 15 may reach up to about 1000 nm. Coating 15 may be a low-friction / low-wear coating. For example, the deposited material layer or coating 15 may include, for example, DLC, CrN, or diamond. Coating 15 may include a wear-resistant material with a hardness greater than 6 GPa. Preferably, the material has a hardness greater than 20 GPa. Diamond-like carbon, chromium nitride, and diamond are known wear-resistant materials.

[0078] Since the thickness removed in step S3 is usually greater than the thickness restored by the newly provided coating 15 in step S4, the total thickness of the substrate support WT is reduced each time the substrate support WT is refurbished according to steps S2 to S4.

[0079] In the example, for some lithography apparatuses, the substrate support WT can only be refurbished two or three times according to steps S2 to S4 before its thickness falls below the minimum thickness. The minimum thickness refers to the thickness of the substrate support WT; if it falls below this thickness, further refurbishment will result in the substrate support WT becoming too thin to hold the substrate W with a standard thickness (e.g., 750 μm to 800 μm). If the substrate support WT is too thin, the upper surface of the substrate W is not in the plane of one or more sensors holding the substrate support WT (e.g., the second positioner PW). This may impair the proper functioning of one or more sensors. A substrate support WT below the minimum thickness may also result in a step between the upper surface of the substrate W and the outside of the substrate stage. Such a step may prevent the system providing the immersion liquid for immersion lithography from operating correctly.

[0080] In step S2, if it is determined that the thickness of the (used) substrate support WT is less than the minimum thickness, the method proceeds to step S5 (see reference). Figure 5A ).

[0081] In step S5, material is deposited on the second surface 6 to form a coating 24 with a thickness t (reference). Figure 5B This increases the overall thickness of the substrate support WT. Figure 5B The substrate support WT is schematically shown after the deposition of coating 24. Coating 24 may comprise the same or similar material as the body 2 or the second protrusion 12 used to form the substrate support WT. For example, the deposited material may include silicon carbide. Coating 24 may be selectively deposited on the distal portion 13 of the second protrusion 12, for example, using a mask. Thus, the distal portion 13 of the second protrusion 12 includes coating 24 configured for direct contact with the second positioner PW.

[0082] In some embodiments, the coating 24 has a thickness of at least 1 μm. In some cases (e.g., when refurbishment will only remove a small amount of material), this is sufficient to increase the thickness of the substrate support beyond the minimum thickness. In other embodiments, the minimum thickness t of the coating 24 may be at least 3 μm. This allows at least 3 μm of material to be removed from the first surface 4 (ensuring removal of any worn portions) without reducing the thickness of the substrate support. The thickness t of the coating 24 may reach a maximum of 50 μm. Removing more than 50 μm of material may be problematic because the corresponding reduction in the height of the first protrusions 8 may make it difficult to generate a vacuum W under the substrate during use. However, the thickness t of the coating 24 may be greater than 50 μm, for example, up to 300 μm. With such a thickness, it may be possible to remove some material from the region of the first surface 4 between the first protrusions 8 in order to restore at least some of the height of the first protrusions 8.

[0083] In some embodiments of this method, the material of coating 24 (e.g., silicon carbide) may be deposited by physical vapor deposition. In an example, silicon carbide may be deposited on the second surface 6 by sputter deposition to form coating 24. Sputter deposition may be performed at low temperatures, reducing thermal stress induced in the substrate support WT during and after the deposition process. In some embodiments of this method, an intermediate layer or pretreatment may be deposited prior to depositing coating 24, thereby reducing stress induced in the substrate support WT and improving adhesion of coating 24 to the substrate support WT.

[0084] In other embodiments of the method, the material of coating 24 (e.g., silicon carbide) may be deposited by chemical vapor deposition. Chemical vapor deposition is typically performed at higher temperatures than sputtering deposition, but this technique is able to deposit material to form a thicker coating and may be uniformly applied to multiple different surfaces of the same component.

[0085] In step S6, material is removed from the first surface 4. Removing material from the first surface 4 includes: referencing... Figure 5B , Figure 5C The first surface is finely ground to remove the worn portion 22 (typically several micrometers thick) from the first surface. The thickness of the removed worn portion 22 can be several micrometers. In some cases, 1 μm or more of material may be removed. In this case, there is a risk that some worn portion may not be completely removed. For example, at least 3 μm of material may be removed to ensure complete removal of the worn portion 22.

[0086] In respectively Figure 5B and Figure 5CThe diagram shows the substrate support WT before and after fine grinding. The thickness Δ removed is less than the thickness t added by coating 24, such that the resulting thickness T' of the substrate support WT in step S6 is greater than the thickness T of the substrate support WT in step S2 (reference). Figure 5C ).

[0087] If the thickness t of the added coating 24 (at least at a portion of the second surface) is equal to the thickness Δ removed at (at least a portion of) the first surface 4, then the thickness of the worn portion is not compensated. To also compensate for the worn portion, the thickness t of the added coating 24 is greater than the thickness Δ of the removed material layer. This means that the thickness t of the added coating 24 at the second surface 6 is at least the same as or greater than the thickness Δ of the removed material layer. Therefore, the thickness t of the added coating 24 at the second surface 6 is the same as (equal to) or greater than the thickness Δ of the removed material layer. In this way, the added material layer may compensate for material wear and material removal at the first surface 4, thereby (approximately) maintaining the thickness of the substrate support WT.

[0088] In step S7, the new coating 15 is deposited on the distal portion 9 of the first protrusion 8 and the distal portion 18 of the first vacuum seal 16 (see...). Figure 5D This process produces a refurbished substrate support WT with a final thickness greater than that at step S2. This coating may be a low-friction / low-wear coating. The material layer forming the new coating 15 may include, for example, DLC, CrN, or diamond. The new coating 15 may comprise a wear-resistant material with a hardness greater than 6 GPa. Preferably, the material has a hardness greater than 20 GPa. The refurbished substrate support WT is suitable for reuse in the photolithography apparatus LA at step S1.

[0089] In some embodiments of this method, the coating 24 of the distal end 13 of the second protrusion 12 may also be fine-ground after step S5 to achieve a desired level of surface flatness and smoothness at the coating 24. In such embodiments, the thickness of the coating 24 may be increased to compensate for material removal during the fine-grinding of the coating 24.

[0090] Steps S5 and S6 may be performed in reverse order—such that the first surface 4 is removed before the material is deposited on the second surface 6.

[0091] In reference Figures 3 to 5D In the described method 100, the coating 24 is adapted to the receiving surface material. Typically, the material deposited on the second surface to form the coating may include the same material as the second surface of the substrate support (e.g., silicon carbide). In alternative examples, the coating may consist of silicon dioxide or silicon nitride. Other coating materials may be used, including ceramics. The coating material (e.g., ceramic) may have a coefficient of thermal expansion that is as high as that of silicon.

[0092] In reference Figures 3 to 5D In the described method 100, a material (e.g., silicon carbide) is selectively deposited at the distal portion 13 of the second protrusion 12 to form a coating 24. In other embodiments, the material may be uniformly deposited over the second surface 6 to form a uniform coating. That is, the material is deposited between and on the second protrusions 12. Optionally, portions of the uniform coating may be selectively removed from the region between the second protrusions 12, such that the coating remains only at the distal portion 13 of the second protrusions 12. Removing the deposited material between the protrusions 12 may help reduce stress within the substrate support WT. Methods for selectively removing portions of the uniform coating may include direct laser ablation and dry etching. Different techniques may be used to remove the material between the protrusions 12.

[0093] In some embodiments, a further coating may be formed by depositing material onto the first surface 4. By depositing material over the substrate support WT, the first surface 4 and the second surface 6 can be uniformly coated, increasing the thickness of the first surface 4 and the second surface 6 of the substrate support WT. The initial coating and the further coating may be made of the same material.

[0094] In reference Figures 3 to 5D The method 100 described may also be used to modify the thickness of the substrate support. For example, the substrate support WT may be modified to allow the use of a substrate W with a thickness lower than the standard value. In order to keep such a substrate W such that the target portion of the substrate is within the focal plane of the projection system PS, the substrate support WT may be increased in thickness by depositing a material such as silicon carbide on a second surface to form a coating. In the example, the coating thickness may be up to 200 μm.

[0095] Those skilled in the art will understand that material removal at, for example, the first surface 4 can be accomplished by grinding or etching the surface of interest. These techniques may be used in conjunction with grinding (fine grinding or polishing) the first surface 4.

[0096] After material is deposited on the first surface 4 (new coating 15), the newly formed protrusion surface may be planarized by ion beam shaping (IBF) or reactive ion etching (RIE).

[0097] It should be understood that cleaning steps or actions may be used to clean the first surface 4 and / or the second surface 6 before depositing material on the first surface 4 and the second surface 6. Cleaning surfaces 4 and 6 promotes adhesion between the deposited material and the receiving surface. Hydrogen plasma or oxygen plasma treatment may be used before material deposition.

[0098] In some cases, a protrusion is not provided at the second surface 6 of the substrate support WT. Similar to surfaces including protrusions, a material layer may be deposited on a flat surface to adapt the substrate support to a photolithography apparatus. Therefore, the method disclosed herein is not limited to substrate supports including protrusions at the first and second surfaces.

[0099] Those skilled in the art will understand that the diamond material layer may be a polycrystalline, monocrystalline (e.g., single crystal) or (nano) ultrafine crystalline diamond layer.

[0100] The new coating 15 provided at the distal portion 9 of the first protrusion 8 and the distal portion 18 of the first vacuum seal 16 may be a doped material coating. By means of dopants, not only the conductivity can be altered, but also the hardness of, for example, the diamond layer can be changed / tuned. Typical dopants include nitrogen (N), phosphorus (P), fluorine (F), and boron (B), but are not limited to these elements. For example, a fluorinated diamond layer may be obtained, for example, by plasma-induced surface fluorination. Nitrogen will form volatile hydrides and oxide species NxOyHz (e.g., NO, NO2, or NH3) and will maintain the original conductivity, while other dopants (e.g., B or P) may oxidize and form a dielectric coating several nanometers thick. Highly N-doped diamond is typically ultrananocrystalline. Other typical dopants (B, P) may form a continuous oxide layer with a thickness >1 nm, which can form a dielectric layer. Dopant concentrations of >100 ppm can be used. When the diamond layer is doped with boron, the resistivity is in the range of about 100 kΩcm to about 0.01 Ωcm. It should be noted here that the choice of a particular dopant may depend on the desired roughness at the nanoscale.

[0101] While this article may specifically refer to the application of photolithography equipment in IC manufacturing, it should be understood that the photolithography equipment described herein may also have other applications. Other possible applications include: the manufacturing of integrated optical systems, the guiding and detection of patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, etc.

[0102] While specific embodiments of the invention may be referenced herein in the section concerning lithography apparatus, these embodiments may also be used in other devices. Embodiments of the invention may form part of mask inspection equipment, metrology tools, or any apparatus for measuring or processing objects such as wafers (or other substrates), masks (or other patterning apparatus). These apparatuses may be commonly referred to as lithography tools. Such lithography tools may be used in a vacuum environment or in ambient (non-vacuum) environments.

[0103] Although the foregoing may have specifically referenced the use of embodiments of the invention in the context of optical lithography, it should be understood that the invention is not limited to optical lithography in this context and may be used in other applications such as imprint lithography.

[0104] Various aspects of the invention are set forth in the following claims: 1. A method for refurbishing a substrate support, the substrate support comprising: A first surface, which is configured to support a substrate; and A second surface, which is configured to be opposite to the first surface; The method includes: Material is deposited on a second surface to form a coating, the coating increasing the thickness of the substrate support; and Remove material from the first surface. 2. The method according to item 1, wherein after the material is deposited on the second surface, the material is removed from the first surface. 3. The method according to any of the preceding clauses, wherein the thickness of the coating is at least 1 μm. 4. The method according to any of the preceding clauses, wherein the thickness of the coating reaches a maximum of 300 μm. 5. The method according to any of the preceding clauses, wherein the second surface is defined by a protruding portion configured to support the substrate support. 6. The method according to item 5, wherein the material is selectively deposited on the protrusion on the second surface. 7. The method according to any of the preceding clauses, wherein the material is uniformly deposited above the second surface. 8. The method according to item 7, wherein the method further comprises selectively reducing portions of the coating. 9. The method according to any of the preceding clauses, wherein removing material from the first surface includes fine grinding of the first surface. 10. The method according to item 9, wherein the method comprises depositing a wear-resistant material having a hardness of at least 6 GPa on at least a portion of the first surface. 11. The method according to claim 9, wherein the method comprises depositing a wear-resistant material having a hardness of at least 20 GPa on at least a portion of the first surface. 12. The method according to clause 9, 10 or 11, wherein the method comprises depositing a diamond-like carbon coating, a chromium nitride coating or a diamond coating on at least a portion of the first surface. 13. The method according to any one of clauses 10 to 12, wherein after depositing the (wear-resistant) material on the first surface, the first surface is planarized by ion beam shaping or reactive ion etching. 14. The method according to any of the preceding clauses, wherein the method further comprises finely grinding the coating. 15. The method according to any of the preceding clauses, wherein the material deposited on the second surface to form a coating comprises the same material as the second surface of the substrate support. 16. The method according to any of the preceding clauses, wherein the material deposited on the second surface to form a coating comprises a material adapted to the second surface of the substrate support. 17. The method according to any of the preceding clauses, wherein the material deposited on the second surface to form a coating is silicon carbide. 18. The method according to any of the preceding clauses further includes cleaning the first surface and / or the second surface prior to material deposition. 19. The method according to clause 18, wherein cleaning is performed by means of hydrogen plasma or oxygen plasma. 20. The method according to any of the preceding clauses, wherein the material is deposited by physical vapor deposition. 21. The method according to clause 20, wherein the material is deposited by sputter deposition. 22. The method according to any one of clauses 1 to 19, wherein the material is deposited by chemical vapor deposition. 23. A substrate support, comprising: The first surface is configured to support the substrate; A second surface, which is opposite to the first surface; and A coating that covers at least a portion of the second surface. 24. The substrate support according to clause 23, wherein the coating comprises the same material as the second surface of the substrate support. 25. The substrate support according to clause 23 or 24, wherein the coating is silicon carbide. 26. A substrate support, wherein the substrate support is refurbished according to the method described in any one of items 1 to 22.

[0105] Although specific embodiments of the invention have been described above, it should be understood that the invention may be practiced in ways other than those described. The foregoing description is intended to illustrate, not limit, the invention. Therefore, those skilled in the art will understand that modifications may be made to the invention without departing from the scope of the claims set forth below.

Claims

1. A method for refurbishing a substrate support, the substrate support comprising: The first surface is configured to support the substrate; as well as The second surface is opposite to the first surface; The method includes: Material is deposited on the second surface to form a coating, the coating increasing the thickness of the substrate support; Material is removed from the first surface, the removed material having a first thickness; and The coating has a second thickness, which is equal to or greater than the first thickness.

2. The method of claim 1, wherein after the material is deposited on the second surface, the material is removed from the first surface.

3. The method according to any one of the preceding claims, wherein the thickness of the coating is at least 1 μm.

4. The method according to any of the preceding claims, wherein the second surface is defined by a protrusion portion, the protrusion being configured to support the substrate support.

5. The method of claim 4, wherein the material is selectively deposited on the protrusions of the second surface.

6. The method according to any one of the preceding claims, wherein the material is uniformly deposited above the second surface.

7. The method of claim 6, wherein the method further comprises selectively reducing portions of the coating.

8. The method according to any one of the preceding claims, wherein removing material from the first surface comprises fine grinding the first surface.

9. The method of claim 8, wherein the method comprises: A wear-resistant material with a hardness of at least 6 GPa is deposited on at least a portion of the first surface.

10. The method according to claim 8 or 9, wherein the method comprises: A diamond-like carbon coating, a chromium nitride coating, or a diamond coating is deposited on at least a portion of the first surface.

11. The method according to claim 9 or 10, wherein the wear-resistant material is diamond-like carbon or diamond including a dopant, the dopant being at least one of nitrogen, phosphorus, fluorine and boron.

12. The method according to claim 9, 10 or 11, wherein after depositing the material at the first surface, the first surface is planarized by ion beam shaping or by reactive ion etching.

13. The method according to any of the preceding clauses, wherein the material deposited on the second surface to form the coating comprises: The material adapted to the second surface of the substrate support.

14. The method according to any of the preceding clauses, wherein the material deposited on the second surface to form the coating is at least one of the following: silicon carbide, diamond-like carbon, chromium nitride, and diamond.

15. A substrate support, wherein the substrate support is refurbished according to any one of claims 1 to 14.

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