Hydrophobic surface modification of polishing pads

Abstract

A polishing pad including a polishing layer having a working surface of a first material having a land region including at least one of a plurality of pores and a plurality of asperities, and a cover layer disposed on at least a portion of the working surface, wherein the cover layer is of a second material, the second material being more hydrophobic than the first material.

Description

[0001] HYDROPHOBIC SURFACE MODIFICATION OF POUISHING PADS

[0002] Summary

[0003] In some aspects of the present description, a polishing pad is provided, the polishing pad including a polishing layer having a working surface of a first material and having a land region including at least one of a plurality of pores and a plurality of asperities, and a cover layer disposed on at least a portion of the working surface. The cover layer includes a second material, and the second material is more hydrophobic than the first material.

[0004] In some aspects of the present description, a polishing system is provided, the polishing system including a polishing pad and a polishing solution. The polishing pad includes a polishing layer having a working surface of a first material and a cover layer including a second material disposed on at least a portion of the working surface. The second material is more hydrophobic than the first material.

[0005] In some aspects of the present description, a method of polishing a substrate is provided, the method including providing a polishing pad, providing a substrate, contacting the working surface of the polishing layer with the substrate surface, and moving the polishing pad and the substrate relative to one another while maintaining contact between the working surface of the polishing pad and the substrate surface, wherein polishing is conducted in the presence of a polishing solution. The polishing pad includes a polishing layer having a working surface of a first material and a cover layer including a second material disposed on at least a portion of the working surface. The second material is more hydrophobic than the first material.

[0006] In some aspects of the present description, a method of creating a polishing pad is provided, the method including providing a polymeric pad including a polishing layer having a working surface of a first material and having a land region having at least one of a plurality of pores and a plurality of asperities and covering at least a portion of the working surface with a cover layer including a second material. The second material is more hydrophobic than the first material.

[0007] Brief Description of the Drawings

[0008] FIGS. 1A and IB provide cross-sectional views of a polishing pad, in accordance with an embodiment of the present description;

[0009] FIG. 2 is a side view of a polishing system and method of polishing a substrate, in accordance with an embodiment of the present description;

[0010] FIG. 3 A is a micrograph of a polishing pad showing pores and asperities on the working surface of a polishing pad, in accordance with an embodiment of the present description; FIG. 3B is a schematic, top view of a polishing pad showing a pattern of channels separating sections of a working surface of a polishing pad, in accordance with an embodiment of the present description; and

[0011] FIG. 4 illustrates a method of creating a polishing pad, in accordance with an embodiment of the present description.

[0012] Detailed Description

[0013] In the following description, reference is made to the accompanying drawings that form a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description, therefore, is not to be taken in a limiting sense.

[0014] Various articles, systems, and methods have been employed for the polishing of substrates. The polishing articles, systems, and methods are selected based on the desired end use characteristics of the substrates, including but not limited to, surface finish, e.g. surface roughness and defects (scratches, pitting and the like), and planarity, including both local planarity, i.e. planarity in a specific region of the substrate, and global planarity, i.e. planarity across the entire substrate surface.

[0015] The polishing of substrates such as semiconductor wafers presents particularly difficult challenges, as end-use requirements may be extremely stringent due to the micron-scale and even nano-scale features that need to be polished to a required specification, e.g., surface finish. Often, along with improving or maintaining a desired surface finish, the polishing process also requires material removal, which may include material removal within a single substrate material or simultaneous material removal of a combination of two or more different materials, within the same plane or layer of the substrate.

[0016] Currently, many polishing processes employ polishing pads with included pad topography, pad surface topography being particularly important. One type of topography relates to pad porosity (e.g., pores within the pad). The porosity is desired, as the polishing pad is usually used in conjunction with a polishing solution, typically a slurry (a fluid containing abrasive particles), and the porosity enables a portion of the polishing solution deposited on the pad to be contained in the pores. Generally, this is thought to facilitate the polishing process.

[0017] A second type of pad topography critical to the polishing process relates to asperities (i.e., projections or features) on the pad surface. This surface topography includes asperities that will come into physical contact with the substrate surface being polished. The size and the distribution of the asperities are thought to be a key parameter with respect to the pad polishing performance.

[0018] Often, along with improving or maintaining a desired surface finish, the polishing process may require removing material from the surface of the substrate (e.g., to achieve a required level of planarization in the substrate surface). Whether the working surface of a polishing pad has pores, asperities, or a combination thereof, one key to optimal performance (e.g., increased material removal rate) may include maximizing the amount of slurry and abrasive particles on the surfaces of the polishing pad (e.g., the tops of the asperities) that are in contact with the surface of the substrate (i.e., increasing the amount of slurry between the working surface of the pad and the surface of the substrate), rather than away from the substrate surface (e.g., on the land area between asperities, or inside the pores).

[0019] According to some aspects of the present description, a polishing pad is provided wherein the surfaces of the polishing pad in contact with a substrate (e.g., the tops of asperities) are relatively more hydrophilic than any surfaces of the polishing pad that are typically not in direct contact with the substrate. One way of increasing the relative hydrophilic state of the asperities or other surfaces in contact with the substrate would be to coat the working surface of the polishing pad (or just the tops of the asperities or land around pores) with a coating that is relatively hydrophilic, such that the polishing solution (e.g., a slurry with abrasive particles) is attracted to the surfaces in contact with the substrate during polishing. However, this relatively hydrophilic coating will be quickly worn off during polishing as the coated portions of the working surface move against the substrate, and the relatively hydrophilicity of the working surface only lasts for a short while.

[0020] According to some aspects of the present description, however, is an article and method wherein the entire working surface of the polishing pad is coated with a hydrophobic coating (i.e., a coating that is relatively more hydrophobic than the material of the working surface itself). In this manner, when the polishing pad is in use, the relatively hydrophobic coating will be worn off from the portions of the working surface which are in contact with the substrate during polishing, but will substantially remain on the portions of the working surface (e.g., surfaces below the asperities, such as the land region or the interior surfaces of the pores), creating a relative increase in hydrophilicity in the now uncovered portions of the working surface. That is, the hydrophobic coating that covers the entire working surface will be removed through use (or through a separate conditioning process) from those portions of the working surface which are in contact with the substrate or conditioning surface. Without the hydrophobic coating, these contact surfaces (e.g., the tips of the asperities) will be relatively less hydrophobic (more hydrophilic) than the non-contact surfaces.

[0021] According to some aspects of the present description, a polishing pad may include a polishing layer having a working surface of or including a first material and having a land region having at least one of a plurality of pores and a plurality of asperities. In some embodiments, the polishing pad may further include a cover layer disposed on at least a portion of the working surface. In some embodiments, the cover layer is of or includes a second material. In some embodiments, the second material may be relatively more hydrophobic than the first material. In some embodiments, the polishing pad is a chemical mechanical polishing pad.

[0022] In some embodiments, each asperity of the plurality of asperities may include a top surface (e.g., a flat “plateau” top), wherein the cover layer covers at least a portion of the top surfaces. In some embodiments, each pore of the plurality of pores may include one or more interior surfaces (e.g., the interior wall and / or bottom of the pore), wherein the cover layer covers at least a portion of the one or more interior surfaces and at least a portion of the land region.

[0023] In some embodiments, when the polishing pad includes the plurality of asperities, the average height of the asperities above the land region may be less than about 50 microns, or less than about 40 microns, or less than about 30 microns, or less than about 20 microns, or less than about 10 microns. In some embodiments, when the polishing pad includes the plurality of pores, an average depth of the pores below the land region may be less than about 200 microns, or less than about 150 microns, or less than about 100 microns, or less than about 90 microns, or less than about 80 microns, or less than about 70 microns, or less than about 50 microns, or less than about 40 microns, or less than about 30 microns, or less than about 20 microns, or less than about 10 microns. In some embodiments, the average thickness of the cover layer may be less than about 1 micron, or less than about 900 nm, or less than about 800 nm, or less than about 700 nm, or less than about 600 nm, or less than about 500 nm, or less than about 400 nm, or less than about 300 nm, or less than about 200 nm, or less than about 100 nm, or less than about 75 nm, or less than about 50 nm, or less than about 40 nm, or less than about 30 nm.

[0024] In some embodiments, the polishing layer of the polishing pad may further include a plurality of independent or inter-connected channels. In some such embodiments, an average width of each channel in the plurality of independent or inter-connected channels may be less than about 500 microns, or less than about 400 microns, or less than about 300 microns, or less than about 200 microns, or less than about 100 microns, or less than about 50 microns.

[0025] In some embodiments, the working surface of the polishing pad may include at least one of a polyurethane, a polyvinyl chloride (PVC), a polytetrafluoroethylene (PTFE), polyethylene (PE), a polyimide (PI), a polyetheretherketone (PEEK), a polysulfone (PSU), and a polypropylene (PP).

[0026] In some embodiments, the cover layer may be coated on the at least a portion of the working surface by a coating process. In some such embodiments, the coating process may include one or more of plasma enhanced chemical vapor deposition, chemical vapor deposition, atomic layer deposition, sputtering, spray coating, dip coating, spin coating, and solvent die coating. In some such embodiments, the second material (being coated) may include at least one of a methyl-terminated SiCxHy (e.g., a methyl group), an organofluorine, a fluoropolymer, a non-aromatic hydrocarbon polymer, and a silicone.

[0027] Methyl groups can be formed from molecular fragmentation of hexamethyldisiloxane through plasma dissociation to create a hydrophobic layer, although any method of creating a methyl- terminated surface (methyl-terminated SiCxHy) may provide similar functionality. Similarly, organofluorine coatings may be formed from molecular fragmentation of fluorocarbons and oxyfluorocarbons through plasma dissociation and deposition. Exemplary plasma deposition processes and apparatus are described in WO 2018 / 005109 (Yu et al,) and W02020 / 0030207 (Van Lengerich et al,), which are incorporated herein by reference. Hexamethyldisiloxane, tetraethyl orthosilicate, tetramethylsilane, hexamethyldisilane, or trimethylamine are all appropriate precursors to create a methylated surface. Additionally, fluorinated compounds such as fluoropolymers, nonaromatic hydrocarbon polymers, silicones, and mixtures and combinations thereof may be appropriate layers to increase the relative hydrophobicity of the surface.

[0028] In some embodiments, the polishing pad may include an additive (e.g., an additive added into the first material). In some such embodiments, the additive includes the second material, and, upon processing, the additive may migrate to a surface of the polishing pad to form the cover layer. In some such embodiments, the additive may include a polymer melt additive as exemplified in US Patent US 10 / 731,056 B2 (“Adhesive articles and methods of making the same”), international publication WO 2023 / 099977 Al (“Melt additives for low surface-energy applications”), and international publication WO 2022 / 144724 Al (“Partially fluorinated sulfonamides for use in pet films”), all of which are incorporated herein by reference.

[0029] According to some aspects of the present description, a polishing system may include any of the embodiments of a polishing pad as described herein and a polishing solution. In some embodiments, the polishing solution may be a slurry (e.g., a slurry including abrasive particles).

[0030] According to some aspects of the present description, a method of polishing a substrate includes providing any of the embodiments of a polishing pad as described herein, providing a substrate (e.g., a semiconductor wafer), contacting the working surface of the polishing layer with the substrate surface, and moving the polishing pad and the substrate relative to one another while maintaining contact between the working surface of the polishing pad and the substrate surface, wherein polishing is conducted in the presence of a polishing solution (e.g., such as a slurry containing abrasive particles).

[0031] In some embodiments, the method of polishing a substrate may further include conditioning the polishing pad by contacting the working surface with a conditioning surface such that at least a portion of the cover layer is removed from at least a portion of the working surface in contact with the conditioning surface. In some such embodiments, the conditioning surface may be the substrate surface, and conditioning the polishing pad may be achieved via a “break in” or conditioning period during an otherwise normal polishing event (i.e., the contact between the polishing pad and the substrate surface may cause at least a portion of the cover layer to be removed, leaving the portions of the working surface in contact with the substrate to be substantially uncovered).

[0032] According to some aspects of the present description, a method of creating a polishing pad includes providing a polymeric pad having a polishing layer with a working surface of or including a first material and having a land region including at least one of a plurality of pores and a plurality of asperities, and covering at least a portion of the working surface with a cover layer or including a second material. In some embodiments, the second material may be more hydrophobic than the first material. In some embodiments, covering at least a portion of the working surface with a cover layer includes coating by a coating process of the second material on the at least a portion of the working surface. In some such embodiments, the coating process may include one or more of plasma enhanced chemical vapor deposition, atomic layer deposition, sputtering, spray coating, dip coating, spin coating, and solvent die coating. In some such embodiments, the second material may include at least one of a methyl -terminated SiCxHy, an organofluorine, a fluoropolymer, a non-aromatic hydrocarbon polymer, and a silicone.

[0033] In some embodiments, covering at least a portion of the working surface with a cover layer may include adding an additive to the polymeric pad. In some such embodiments, the additive may include the second material. In some embodiments, upon processing, at least a portion of the additive may migrate to a surface of the polymeric pad to create the cover layer. In some such embodiments, the additive may include a polymer melt additive as exemplified in US Patent US 10 / 731,056 B2, international publication WO 2023 / 099977 Al, and international publication WO 2022 / 144724 Al.

[0034] In some embodiments, the method may further include substantially removing at least a portion of the cover layer from at least a portion of the working surface. In some such embodiments, removing at least a portion of the cover layer may include conditioning the polishing pad by contacting the working surface with a conditioning surface such that the at least a portion of the cover layer is removed. In some embodiments, the at least a portion of the working surface may include a portion of the working surface in contact with the conditioning surface. In some such embodiments, the conditioning surface may be at least one of the substrate surface, a polymeric conditioner, an abrasive conditioner, and a retaining ring.

[0035] Turning now to the figures, FIGS. 1A and IB provide cross-sectional views of an embodiment of a polishing pad according to the present description. Looking first at FIG. 1 A, a polishing layer 10 includes a working surface 12 opposite a non- working surface 13. In some embodiments, working surface 12 may include a land region 14 which may include at least one of a plurality of pores 16 and a plurality of asperities 18. In some embodiments, polishing layer 10 may further include a plurality of independent or inter-connected channels 19.

[0036] In some embodiments, when present, each asperity 18 of the plurality of asperities may include a top surface 18a. In some embodiments, when present, each pore 16 of the plurality of pores may include one or more interior surfaces 16a (e.g., the surfaces forming the inside of the pore, including any bottom surfaces).

[0037] In some embodiments, when present, an average height H of the asperities 18 above the land region 14 may be less than about 50 microns, or less than about 40 microns, or less than about 30 microns, or less than about 20 microns, or less than about 10 microns. In some embodiments, when present, an average depth D of the pores 16 below the land region 14 may be less than about 200 microns, or less than about 150 microns, or less than about 100 microns, or less than about 90 microns, or less than about 80 microns, or less than about 70 microns, or less than about 50 microns, or less than about 40 microns, or less than about 30 microns, or less than about 20 microns, or less than about 10 microns. In some embodiments, an average width W of each channel 19 in the plurality of independent or inter-connected channels 19 may be less than about 500 microns, or less than about 400 microns, or less than about 300 microns, or less than about 200 microns, or less than about 100 microns, or less than about 50 microns.

[0038] Turning now to FIG. IB, a cover layer 20 may be disposed on at least a portion of working surface 12 of polishing layer 10, creating polishing pad 100. In some embodiments, cover layer 20 may be disposed on land region 14, asperities 18 (including top surfaces 18a), pores 16 (including interior surfaces 16a), and channels 19. In some embodiments, cover layer 20 may include a second material which is relatively more hydrophobic than the first material of polishing layer 10.

[0039] In some embodiments, an average thickness T of the cover layer may be less than about 1 micron, or less than about 900 nm, or less than about 800 nm, or less than about 700 nm, or less than about 600 nm, or less than about 500 nm, or less than about 400 nm, or less than about 300 nm, or less than about 200 nm, or less than about 100 nm, or less than about 75 nm, or less than about 50 nm, or less than about 40 nm, or less than about 30 nm. In some embodiments, the average thickness T of the cover layer may be such that the cover layer is readily worn off surfaces in contact with the substrate during conditioning or through normal use of the polishing pad 100.

[0040] FIG. 2 schematically illustrates an example of a polishing system 200 for utilizing polishing pads and methods in accordance with some embodiments of the present disclosure. As shown, polishing system 200 may include a polishing pad 100 and a polishing solution 260. Polishing system 200 may further include one or more of the following: a substrate 210 to be polished or abraded, a platen 240 and a carrier assembly 230. In some embodiments, an adhesive layer 270 may be used to attach the polishing pad 100 to platen 240 and may be part of polishing system 200. Polishing solution 260 may be a layer of solution (e.g., a slurry containing abrasive particles) disposed about a major surface of the polishing pad 100. Polishing pad 100 may be any of the polishing pad embodiments of the present disclosure and includes at least one polishing layer (not shown, but see, for example, polishing layer 10 of FIGS. 1A and IB), as described herein. In some embodiments, polishing solution 260 may typically be disposed on working surface 12 of the polishing layer 10 of polishing pad 100. In some embodiments, polishing solution 260 may also be at the interface between substrate 210 and polishing pad 100.

[0041] During operation of polishing system 200, a drive assembly 245 may rotate (see, e.g., arrow A) the platen 240 to move the polishing pad 100 to carry out a polishing operation. In some embodiments, polishing pad 100 and polishing solution 260 may separately, or in combination, define a polishing environment that mechanically and / or chemically removes material from or polishes a major surface of a substrate 210. To polish the major surface of the substrate 210 with the polishing system 200, carrier assembly 230 may urge substrate 210 against a polishing surface of polishing pad 100 in the presence of polishing solution 260. In some embodiments, platen 240 (and thus the polishing pad 100) and / or carrier assembly 230 may then move relative to one another to translate the substrate 210 across the polishing surface of polishing pad 100. In some embodiments, carrier assembly 230 may rotate (see, e.g., arrow B) and optionally transverse laterally (see, e.g., arrow C). As a result, the polishing layer of polishing pad 100 may remove material from the surface of substrate 210.

[0042] In some embodiments, inorganic abrasive material, e.g. inorganic abrasive particles, may be included in the polishing layer to facilitate material removal from the surface of the substrate. In other embodiments, the semiconductor wafer surface to be polished, i.e. in contact with the working surface 12 of polishing pad 100, may include, but is not limited to, at least one of a dielectric material, an electrically conductive material, a barrier / adhesion material and a cap material. The dielectric material may include at least one of an inorganic dielectric material, e.g., silicone oxide and other glasses, and an organic dielectric material. The metal material may include, but is not limited to, at least one of copper, tungsten, aluminum, silver, and the like. The cap material may include, but is not limited to, at least one of silicon carbide and silicon nitride. The barrier / adhesion material may include, but is not limited to, at least one of tantalum and tantalum nitride.

[0043] It is to be appreciated that polishing system 200 of FIG. 2 is only one example of a polishing system that may be employed in connection with the polishing pads and methods of the present disclosure, and that other conventional polishing systems may be employed without deviating from the scope of the present disclosure.

[0044] FIG. 3 A is a micrograph of an embodiment of a polishing pad 100 showing pores 16 and asperities 18 on the working surface 12 of the polishing pad 100. Pores 16 extend down (into the page) into polishing pad 100 from land region 14. Asperities 18 extend up (out of the page) from polishing pad 100 from land region 14.

[0045] FIG. 3B is a schematic, top view of an embodiment of a polishing pad 100 showing a pattern of channels 19 separating sections of a working surface 12 of the polishing pad 100. The embodiment of FIG. 3B is one example pattern of channels 19 across working surface 12 (a “herringbone” pattern) and is not meant to be limiting. Any pattern of channels 19, either interconnected or separated, is within the scope of the present description.

[0046] FIG. 4 illustrates one embodiment of a method of creating a polishing pad, according to the present description. In step (A) of the method, a polymeric pad 10 is provided, the polymeric pad 10 including a working surface 12 of and / or including a first material and having a land region 14 having at least one of a plurality of pores 16 and a plurality of asperities 18. In step (B), at least a portion of working surface 12 of polymeric pad 10 is covered with a cover layer 20, cover layer 20 of and / or including a second material. In some embodiments, the second material is more hydrophobic than the first material.

[0047] In some embodiments, step (B), covering at least a portion of the working surface with a cover layer, may include coating by a coating process of the second material on the at least a portion of the working surface. In some such embodiments, the coating process may include one or more of plasma enhanced chemical vapor deposition, atomic layer deposition, sputtering, spray coating, dip coating, spin coating, and solvent die coating. In some such embodiments, the second material may include at least one of a methyl-terminated SiCxHy, an organofluorine, a fluoropolymer, a nonaromatic hydrocarbon polymer, and a silicone.

[0048] In other embodiments, step (B), covering at least a portion of the working surface with a cover layer to create polishing pad 100, may include adding an additive to polymeric pad 10. In some such embodiments, the additive may include the second material, and, upon processing, at least a portion of the additive may migrate to a surface of polymeric pad 10 to create the cover layer. In some embodiments, the additive may include a polymer melt additive.

[0049] In some embodiments, the method may further include step (C), which includes substantially removing at least a portion of the cover layer 20 from at least a portion of working surface 12. In some such embodiments, removing at least a portion of cover layer 20 may include conditioning polishing pad 100 by contacting working surface 12 with a conditioning surface 70 such that the at least a portion of the cover layer is removed, creating conditioned polishing pad 100a. In some embodiments, at least a portion of working surface 12 may include any portion of working surface 12 in contact with conditioning surface 70. In some embodiments, conditioning surface 70 may be at least one of the substrate surface, a polymeric conditioner, an abrasive conditioner, and a retaining ring.

[0050] Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1, means that the quantity has a value between 0.9 and 1.1, and that the value could be 1.

[0051] Terms such as “substantially” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “substantially equal” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially equal” will mean about equal where about is as described above. If the use of “substantially parallel” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially parallel” will mean within 30 degrees of parallel. Directions or surfaces described as substantially parallel to one another may, in some embodiments, be within 20 degrees, or within 10 degrees of parallel, or may be parallel or nominally parallel. If the use of “substantially aligned” is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “substantially aligned” will mean aligned to within 20% of a width of the objects being aligned. Objects described as substantially aligned may, in some embodiments, be aligned to within 10% or to within 5% of a width of the objects being aligned. All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control.

[0052] Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed:

1. A polishing pad comprising a polishing layer having a working surface comprising a first material and having a land region comprising at least one of a plurality of pores and a plurality of asperities, and a cover layer disposed on at least a portion of the working surface, wherein the cover layer comprises a second material, the second material being more hydrophobic than the first material.

2. The polishing pad of claim 1, wherein the polishing pad is a chemical mechanical polishing pad.

3. The polishing pad of claim 1, comprising the plurality of asperities, wherein an average height of the asperities above the land region is less than about 50 microns.

4. The polishing pad of claim 1, comprising the plurality of pores, wherein an average depth of the pores below the land region is less than about 200 microns.

5. The polishing pad of claim 1, wherein an average thickness of the cover layer is less than about 1 micron.

6. The polishing pad of claim 1, wherein the polishing layer further comprises a plurality of independent or inter-connected channels.

7. The polishing pad of claim 6, wherein an average width of each channel in the plurality of independent or inter-connected channels is less than about 500 microns.

8. The polishing pad of claim 1, comprising the plurality of asperities, each asperity of the plurality of asperities comprising a top surface, and wherein the cover layer covers at least a portion of the top surfaces.

9. The polishing pad of claim 1, comprising the plurality of pores, each pore of the plurality of pores comprising one or more interior surfaces, and wherein the cover layer covers at least a portion of the one or more interior surfaces and at least a portion of the land region.

10. The polishing pad of claim 1, wherein the working surface comprises at least one of a polyurethane, a polyvinyl chloride (PVC), a polytetrafluoroethylene (PTFE), polyethylene (PE), a polyimide (PI), a polyetheretherketone (PEEK), a polysulfone (PSU), and a polypropylene (PP).

11. The polishing pad of claim 1, wherein the cover layer is coated on the at least a portion of the working surface by a coating process.

12. The polishing pad of claim 11, wherein the coating process comprises one or more of plasma enhanced chemical vapor deposition, chemical vapor deposition, atomic layer deposition, sputtering, spray coating, dip coating, spin coating, and solvent die coating.

13. The polishing pad of claim 11, wherein the second material comprises at least one of a methyl- terminated SiCxHy, an organofluorine, a fluoropolymer, a non-aromatic hydrocarbon polymer, and a silicone.

14. The polishing pad of claim 1, wherein the polishing pad comprises an additive, the additive comprising the second material, wherein, upon processing, the additive migrates to a surface of the polishing pad to form the cover layer.

15. The polishing pad of claim 14, wherein the additive comprises a polymer melt additive.

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