Method for applying a blanket polymer coating to a substrate - Patents.com

Abstract

Techniques are described for applying a cured polymer blanket coating to a surface, and in particular for applying a blanket coated cured polymer coating to a surface of a substrate useful as an electrostatic chuck for processing semiconductor wafers, the cured polymer blanket coating being prepared by applying a coating of a liquid spray solution over the entire surface area of ​​the electrostatic chuck and then curing the blanket coating polymer over the entire surface area of ​​the blanket coating.

Description

[Technical field]

[0001] The following description relates to techniques for applying a cured polymer blanket coating to a surface, and in particular, to techniques for applying a blanket coated cured polymer coating to the surface of a substrate useful as an electrostatic chuck for processing semiconductor wafers. [Background technology]

[0002] An electrostatic chuck is a device that holds and supports a substrate, usually a semiconductor wafer, during the manufacturing process and also removes heat from the substrate without mechanically clamping the substrate.

[0003] During use of an electrostatic chuck, the backside of a substrate is held to the top surface of the electrostatic chuck by electrostatic forces. The substrate is separated from one or more electrodes that are part of the electrostatic chuck by a surface layer of material that covers the electrodes. In a Coulomb chuck, the surface layer is electrically insulating, while in a Johnsen-Rahbek electrostatic chuck, the surface layer is weakly conductive.

[0004] The top surface of the electrostatic chuck may be completely flat or may have one or more protrusions, projections, or other surface features that further separate the backside of the substrate from the covered electrode. Heat contained in the substrate during processing may be transferred from the substrate to the electrostatic chuck by contact thermal conduction with the protrusions or by gas thermal conduction with a cooling gas flowing between the top surface of the chuck and the bottom surface of the substrate. Contact thermal conduction is generally more efficient than gas thermal conduction at removing heat from the substrate. However, the amount of contact between the substrate and the protrusions can be difficult to control.

[0005] In microelectronics manufacturing, as semiconductor and memory device geometries become smaller and smaller and wafers, flat screen displays, reticles, and other processed substrates become larger and larger, the tolerance for particulate contamination of the wafer surface continues to become more stringent. The effects of particle debris from electrostatic chucks are particularly problematic because semiconductor wafers come into physical contact with the clamping surface of the electrostatic chuck. If the top surface of the electrostatic chuck traps any particulate between the top surface of the electrostatic chuck and the bottom surface of the substrate, the trapped particulate may deform the substrate. For example, if the backside of the wafer is electrostatically clamped against a flat reference surface, the trapped particulate may cause deformation of the front side of the wafer, such that the wafer will not have a flat surface. A micron-scale particle (e.g., a 10 micron particle) on a flat electrostatic chuck may displace the surface of the wafer supported by the chuck by a significant amount during wafer processing. Summary of the Invention

[0006] In the art of semiconductor and microelectronic processing, as well as electrostatic chuck technology, there is a continuing need for improved techniques for preparing electrostatic chuck surfaces. There is also a continuing need for improved electrostatic chuck surfaces, for example, electrostatic chuck surfaces that generate a relatively low amount of particulate debris during use.

[0007] As described herein, a new and inventive method has been discovered for applying a layer (also known as a "film") of cured polymer to the surface of an electrostatic chuck. The surface may be completely flat or may include three-dimensional structures such as a main area or protrusions that contact the underside of a wafer supported by the chuck, or a gas seal ring. The cured polymer layer may be in the form of a cured polymer blanket coating that is applied as a coating over the entire surface and cured without selectively curing any portion of the applied spray liquid and without selectively removing any portion of the applied spray liquid.

[0008] The cured polymer blanket coating is prepared by applying a coating of a liquid spray solution over the entire surface area of ​​the electrostatic chuck and then curing the polymer of the blanket coating over the entire surface area of ​​the blanket coating. The coating is cured non-selectively, i.e., cured in a non-patterned manner, specifically without masking portions of the coating. After the liquid polymer solution is applied to the surface and before a final curing step (e.g., a "hard bake" step), no portion of the applied spray solution coating is removed. When the applied spray solution coating is finally cured, the entire cured polymer coating remains over the entire surface of the substrate as a cured polymer blanket coating.

[0009] In one aspect, the present disclosure relates to a method of applying a blanket coated polymer coating to a surface of an electrostatic chuck, the method including applying a spray fluid to a surface of the electrostatic chuck to form a spray fluid coating over the entire surface, the spray fluid including a radiation curable polymer, exposing the entire surface of the spray fluid coating to radiation to form a radiation cured polymer coating, and heating the radiation cured polymer coating to an elevated temperature to remove solvent from the radiation cured polymer coating. [Brief description of the drawings]

[0010] [Figure 1A] FIG. 2 illustrates steps of the exemplary method described. [Figure 1B] FIG. 2 illustrates steps of the exemplary method described. [Figure 2A] FIG. 2 illustrates an exemplary spray path for coating a substrate surface. [Figure 2B] FIG. 2 illustrates an exemplary spray path for coating a substrate surface. [Diagram 3]FIG. 2 illustrates an example of what the top surface of an illustrated electrostatic chuck might look like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] All figures are schematic and not to scale.

[0012] A method for applying a layer of cured polymer (also known as a "film") to the surface of an electrostatic chuck, in the form of a cured polymer blanket coating, is described as follows. The blanket coating is prepared by applying a coating of a liquid polymer solution over the entire surface area of ​​the electrostatic chuck and then curing the polymer of the blanket coating over the entire surface area of ​​the blanket coating. The entire area of ​​the coating is fully cured non-selectively, i.e., fully cured in an unpatterned manner, specifically, fully cured without intentionally and deliberately masking any portion of the coating in a manner that prevents hardening of masked areas of the coating while allowing hardening of other (unmasked) areas of the coating. After application of the liquid polymer solution to the surface, no portion of the coating is removed, and upon hardening, the entire original coating remains over the entire surface as a cured polymer blanket coating.

[0013] As used herein, the term "cured" as in cured coating, cured blanket coating, or cured polymer refers to a coating or polymer of a coating that is fully cured in the intended use of the coating. Depending on the type of polymer and curing system, the polymer may be cured by any useful technique. Exemplary curing techniques may include exposing the polymer to radiation to cure the polymer by a radiation-induced mechanism, exposing the polymer to an elevated temperature to cure the polymer by a thermally-induced mechanism, or curing the polymer by one or more of a combination of radiation and heat. A cured polymer that is at or near the maximum cured state achievable for the polymer, or that is fully cured for its intended use, such as serving as a layer of an electrostatic chuck, may also be referred to as "fully cured."

[0014] A polymer that is only partially cured may be referred to as "partially cured." A polymer that is partially or fully cured by exposure to radiation may be referred to as "radiation cured."

[0015] A polymeric coating that has been exposed to a heating step to remove solvent from the coating (e.g., to a solvent level of less than 10% or 5% relative to the amount of solvent in the coating when the coating is applied) is sometimes referred to as "dried."

[0016] Polymeric materials have been used on the surface of electrostatic chucks to build three-dimensional structures such as protrusions and sealing rings. The polymeric structures are prepared by applying a photopatterned polymer, selectively curing and removing it to generate the desired three-dimensional structures at locations across a major area of ​​the surface. See, for example, U.S. Pat. No. 9,721,821. The process of forming the three-dimensional structures may include applying a polymer layer to the surface, selectively curing portions of the polymer layer, and selectively removing portions of the polymer layer.

[0017] According to this description, a cured polymer coating formed on the surface of an electrostatic chuck is useful as a polymer layer to support a semiconductor wafer during processing of the wafer. The cured (i.e., fully cured) polymer of the coating has mechanical properties useful for supporting a wafer on the top surface of the electrostatic chuck as well as providing useful thermal conduction between the bottom surface of the wafer and the top surface of the chuck. The cured polymer is also useful as a blanket coated polymer film on the top surface of the chuck to prevent debris particles from being removed from the chuck surface or to prevent contact between the chuck surface and the bottom side of the wafer which could generate debris from either surface.

[0018] The term "upper surface" (or "support surface") of an electrostatic chuck refers to the upper (top) surface of the electrostatic chuck that supports a semiconductor wafer for processing the wafer during use of the electrostatic chuck.

[0019] As described, the surface of the electrostatic chuck that is coated with a polymer is a substantially planar surface, e.g., a plane that may be completely flat across the entire area of ​​the surface, or a plane that may include a primary continuous planar surface (sometimes referred to as a "main region") that extends across most of the surface, with numerous structures extending perpendicularly from this plane.

[0020] The surface may be substantially continuous and uninterrupted, or may include openings extending vertically through the surface. One example of an opening may be to allow access through the chuck to a bottom surface of a supported wafer from a location below the top surface of the chuck, for example to allow a mechanical device such as a lift pin to contact the underside of the wafer. Another example of an opening may be to allow gas to flow under the substrate to provide cooling gas or to affect pressure in the space between the top surface of the electrostatic chuck and the underside of a wafer supported by the electrostatic chuck.

[0021] An example of a type of vertically extending structure disposed on the main area may be a plurality of small sized circular (cylindrical) "protrusions" of the type that are often distributed at spaced locations on the surface of the electrostatic chuck to contact the bottom surface of the wafer and support the wafer above the main area of ​​the surface and to provide a space between the bottom surface of the wafer and the main area of ​​the electrostatic chuck. Protrusions of this type may be horizontally spaced in two dimensions and distributed in any useful pattern across the top surface of the electrostatic chuck and may be present in any useful number. When viewed from above the electrostatic chuck, the protrusions are often, but not necessarily, circular. The protrusions may have dimensions (area and height) effective to support a wafer above the main area of ​​the surface of the electrostatic chuck. Exemplary protrusions may be circular in height, such as in the range of about 3 microns to about 12 microns, and may have a diameter in the range of about 500 microns to 1100 microns.

[0022] Different examples of surface structures may be structures that extend vertically above the primary region and along a linear or curved length above the surface of the primary region, such as a ring. One example of a ring structure on the surface of an electrostatic chuck may be a ring disposed around the periphery of the substrate. Another example of a ring structure is a ring seal that surrounds an opening that passes vertically through the substrate or an upper layer of the substrate. The seal ring structure may have any useful dimension, such as a height ranging from about 3 microns to about 12 microns from the primary region. The length of the seal ring may be equal to the perimeter of the outer periphery of the substrate or slightly longer than the perimeter of the vertical opening in the substrate. The width of the seal ring may be any useful width, such as a width ranging from 100 microns to 1000 microns.

[0023] In addition to these types of structures described, surfaces coated with a cured polymer as described may also comprise other functional layers, such as, for example, conductive layers or charge dissipation layers, which may be disposed on the top surfaces of each portion of the main region or protrusions.

[0024] The surface of the electrostatic chuck, including any protrusions, conductive layers, charge dissipation layers, etc., that are coated thereon, can be made from any of a variety of different types of materials known for use as multi-layer top materials in electrostatic chucks. The main region and any protrusions may all be made from a single type of material, i.e., all of these structures may be made from a single material, such as ceramic. Alternatively, the main region may be made from one or more types of materials, and the protrusions may be made from the same or different materials compared to the main region. Exemplary materials generally include ceramics, metals (e.g., conductive metals), polymers, silicon carbide, diamond-like carbon, among others.

[0025] The surface before the polymer is applied as described will be visually flat, with optional vertically extending structures, but will still have a measurable roughness on the micrometer or nanometer scale. Two-dimensional areas of the surface, as well as areas of the main region, will have a measurable roughness, including the tops of vertically extending structures such as protrusions. The roughness of any area of ​​the surface can be measured by known techniques and equipment, such as using a profilometer. Exemplary roughness measurements of the surface of an electrostatic chuck, before being coated with a polymer as described, may be in the range of 0.01 to 10 microns (Ra).

[0026] The polymer applied to the surface may be any curable polymer that can be prepared to form a liquid spray that can be applied as a film onto the structured or unstructured surface of the electrostatic chuck (e.g., by spraying or roller application) and then cured. Non-limiting examples include polymer compositions, sometimes referred to as photocurable or photopatternable polymeric materials, known in the art of manufacturing semiconductor and microelectronic devices, including electrostatic chucks. These generally include epoxy-based, polyimide-based, and benzocyclobutene-based photopatternable polymer compositions. See, e.g., U.S. Pat. No. 9,721,821.

[0027] The polymers are curable and may be applied to a surface as a liquid film and then cured (and solidified) by a chemical curing mechanism that may be activated by radiation, heat, or a combination of radiation and heat, for example, by one or more of: (i) thermal energy, (ii) ultraviolet / visible (UV-VIS) radiant energy, (iii) IR radiant energy, (iv) UV, DUV, EUV, or X-ray radiant energy, (v) microwave radiant energy, (vi) electron flood exposure, (vi) gamma ray exposure, or a combination thereof.

[0028] The polymer in the polymerized state, after curing and drying to remove the solvent used in the spread coating step, may possess useful mechanical characteristics including desired thermal conductivity, desired flexibility (e.g., modulus), hardness, tensile strength, etc.

[0029] The polymer may be coated, cured, and dried to provide a relatively uniform thickness of the cured polymer coating in the range below 6 microns, for example in the range of 3-5 microns.

[0030] To apply the polymer to a surface, the polymer can be formed into a liquid spray that includes the polymer dissolved in a solvent. This spray can be sprayed onto the surface by standard spray equipment or a roller applicator, and has film-forming characteristics when applied to the surface material, meaning that when applied to the surface, the spray wets the surface and forms a substantially uniform, continuous, uninterrupted film (aka "coating" or "layer") over the entire surface. The spray is applied as a blanket coating, and is subsequently cured and dried over the entire area of ​​the blanket coating, leaving a cured blanket polymer coating in place over the entire surface of the electrostatic chuck.

[0031] In the context of the presently described coating, a "blanket coated" coating, or "blanket coating," is a coating that extends across an entire surface as a continuous, uninterrupted coating or film. A spread coating that is applied as a blanket coating across the entire surface of an electrostatic chuck can be cured and solidified to form a "cured blanket polymer coating" (or, for short, a "cured blanket coating") by a curing step that cures the entire blanket coating. The applied spread coated blanket coating is non-selectively cured (fully cured) across its entire surface, with no portions remaining uncured or partially cured, and no portions removed after application. The resulting cured blanket coating is a continuous, uninterrupted cured blanket coating (film) that covers the entire surface of the electrostatic chuck.

[0032] An applied and cured blanket coating that is "continuous" across the surface does not include any open areas that are intentionally left open due to a method step that intentionally leaves portions of the sprayed fluid coating uncured on the surface, other portions cured, and the uncured portions removed. Although not preferred, blanket coatings may include very small amounts of open surface area due to coating defects such as pinholes or other coating imperfections, or due to insufficient coverage of vertical surfaces that are part of a three-dimensional structure, for example, vertical "sidewall" portions of protrusions, ring seals, and the like. In this regard, the blanket coating is applied by a spray coating method designed and intended to place a continuous, uninterrupted, uniform layer of sprayed fluid across the entire surface of the electrostatic chuck, including all vertical surfaces, and is intended to cure the entire sprayed fluid coating without intentionally preventing any significant portions of the sprayed fluid coating from curing, such as by use of a mask. No portion of the blanket coating is intentionally removed from the surface after the sprayed fluid is applied to the surface. To the extent that any portion of the initial (previously exposed) top surface of the electrostatic chuck is not coated with the sprayed fluid or a layer of hardened polymer derived from the sprayed fluid, this uncoated portion may result from a coating defect, such as the failure of the sprayed fluid to contact the vertical surfaces of vertically extending structures, such as protrusions, disposed on the surface.

[0033] In comparison, a cured polymer coating prepared by a process that includes a photopatterning step is not a blanket coating. The photopatterning step, sometimes called "photolithography", is a known technique for selectively curing portions of a photocurable polymer layer disposed on a substrate surface, followed by removal of the uncured portions of the selectively cured layer. The selective curing step is performed by selectively applying radiation to only portions of the layer by masking the portions of the layer that are not intended to be exposed to radiation, and applying radiation to the unmasked portions through openings in the mask. Either the masked or unmasked portions may be cured, and the uncured portions can then be removed (in a "development" step) to leave the desired portions of the original layer.

[0034] 1A and 1B, in which FIG. 1A shows the steps of the method in a schematic manner and FIG. 1B shows the steps as applied to an illustrated substrate 38. According to the method 10, in a first step 22, a liquid spraying liquid 12 is applied to the surface of the substrate 38 by spraying the liquid from a spray nozzle 36 to form a spraying liquid coating 42, which is preferably uniformly applied over the entire surface of the substrate, including any vertical sidewalls. As shown, the substrate 38 comprises a lower layer 40 and an upper layer 44, which may be of any material, such as ceramic. The upper layer 44 comprises optional protrusions 46, which may also be made of any material, such as ceramic. Between each protrusion 46, there is an area of ​​an open field 50. Optionally, but not shown, the substrate 38 may comprise other features, such as a conductive layer, a charge control layer, one or more seal rings, etc.

[0035] In a specific embodiment, the top layer 44 with the protrusions is a ceramic layer prepared by a bead blasting method with masking to create the open fields 50, the protrusions 46, and one or more optional seal rings (not shown), all made from the bead blasted ceramic layer. The roughness of the ceramic surface may be in the range of 0.010 to 10 microns (Ra).

[0036] During the spray fluid application step, the substrate 38 may optionally be heated, but may not be heated and may be maintained at ambient temperature, such as, for example, in the range of 20-23 degrees Celsius. For certain spray fluids, which may include a significant amount (e.g., at least 75, 80, or 90 weight percent) of organic solvent, ambient temperature may be preferred to avoid unwanted evaporation of the organic solvent from the spray fluid when in contact with the surface.

[0037] The sprayed liquid 12 comprises a curable polymer dissolved in a solvent and has physical properties (at ambient temperature, e.g., 20-23 degrees Fahrenheit), including flow properties (e.g., viscosity) and surface tension properties, that enable the sprayed liquid to wet the substrate surface and be uniformly coated as a thin blanket coating on the substrate surface, preferably completely covering all surfaces, including any vertical sidewalls of vertically extending surface structures (e.g., protrusions). In some embodiments, the curable polymer may be electrically conductive, and thus conduct electricity. In some embodiments, the curable conductive polymer may be at least one of polyacetylene (PAC), polyfluorene, polyphenylene, polyphenylenevinylene, polypyrene, polyazulene, polynaphthalene, polypyrrole (PPY), polycarbazole, polyindole, polyazepine, polyaniline (PANI), polyacene, polythiophene (PT), polythiophenevinylene, poly(p-phenylene sulfide) (PPS), poly(p-phenylenevinylene) (PPV), polypyridine, poly(3,4-ethylenedioxythiophene) (PEDOT), polystyrenesulfonate (PSS), poly(triarylamine) (PTAA), poly(hydroxymethyl 3,4-ethylenedioxythiophene) (PEDOT-OH), a derivative of any of the foregoing, or any combination thereof.

[0038] The spray solution can include amounts of solvent and polymer that effectively apply a thin blanket coating over all surfaces of the substrate, even on substrates with three-dimensional structures such as protrusions. To enable the spray solution to become a thin, uniform coating, the spray solution can include a relatively high percentage of organic solvent, for example, at least 75, 80, or 90 weight percent organic solvent, in combination with an amount of polymer below 25, 20, or 10 weight percent based on the total weight of the spray solution.

[0039] The type of solvent used can be any solvent, typically a volatile organic (non-aqueous) solvent capable of dissolving the polymer and forming a solution that can be spray coated onto a surface, as described. Non-limiting examples of useful solvents include gamma butyrolactone, propylene glycol methyl ether acetate, acetone, dodecane, cyclopentanone, and similar organic solvents.

[0040] A spray solution comprising a relatively low percentage of solid polymer and a relatively high percentage of organic solvent can have a viscosity that will produce a thin, uniform coating over an area of ​​a substrate, preferably including the sidewalls of three-dimensional structures such as protrusions. Useful viscosities can be less than 20 centipoise, less than 10 centipoise, or less than 9 centipoise, for example in the range of 3 to 9 centipoise.

[0041] The viscosity of the spray liquid can be calculated in various ways. To prepare a spray liquid for use in a coating method as described, a useful method is to start with a commercial hardenable polymer photoresist solution and add a solvent to reduce the viscosity of the photoresist solution. The viscosity of the diluted solution will be reduced compared to the viscosity of the commercial solution. The viscosity of the commercial solution is known as part of the product specification. The viscosity of the diluted solution can be calculated. In this description and claims, the viscosity of the spray liquid can be calculated using the derivative of the Arrhenius equation. TIFF0007661608000001.tif9170, where η12 is the intrinsic viscosity of the mixture. η1 is, for example, the viscosity of solution 1 from the product specification of a commercial photoresist. η2 is the viscosity of solution 2. X is the mole fraction of liquid 1 and liquid 2.

[0042] This calculation can be used to estimate the viscosity at room temperature (e.g., 20 degrees Celsius) of a solution made by combining a first solution (Solution 1), which is a commercial photoresist product, and a second solution (Solution 2), which is an organic solvent.

[0043] The spray liquid can be applied to the substrate surface using any useful conditions and by any useful spray coating equipment. In some embodiments of the spray coating step, the spray liquid can be applied to the substrate surface in a unidirectional pattern.

[0044] The spray may be coated to a relatively uniform thickness across the surface, for example to a thickness in the range of less than 6 microns, for example 3-5 microns.

[0045] 2A and 2B show examples of spray patterns for applying the spray fluid as described. Figure 2A shows a conventional or standard pattern ("standard raster") whereby a spray coating nozzle applies spray fluid in one direction and then the opposite direction (180 degrees opposite) alternately as it moves laterally (from left to right as shown) to cover the entire surface of the substrate. With each pass over the substrate, spray fluid is applied in a first direction and then a second (opposite) direction.

[0046] FIG. 2B shows an alternative spray pattern, which may now be preferred compared to the pattern of FIG. 2A. FIG. 2B shows a unidirectional spray pattern ("unidirectional raster"), whereby the spray coating nozzle applies spray liquid in only one direction from end to end as the nozzle traverses the substrate surface. The nozzle starts at a position at a first end of the substrate. The nozzle applies a first path of spray liquid while moving in a first direction from the first end of the substrate toward a second, opposite end of the substrate (see solid lines and arrows showing movement from the first substrate end toward the second substrate end during spraying). The nozzle is then returned to the first end, i.e., moving in the opposite (180 degrees opposite) direction (see dashed lines), but the nozzle is turned off and no spray of spray liquid is emitted. The nozzle also moves gradually laterally (from left to right as shown in the figure) and then applies a subsequent path of sprayed liquid adjacent to the first path while moving again in a direction from the first end of the substrate toward the second end of the substrate.

[0047] During the step of spraying the spray liquid onto the surface of the electrostatic chuck, features such as certain openings (eg, openings sized for lift pins, openings sized for earth pins) can be blocked.

[0048] After the spray coating step, in a subsequent step 24, the blanket coating of sprayed fluid is exposed to some form of electromagnetic radiation 14 to chemically cure (at least partially cure) and strengthen or solidify the polymers of the sprayed fluid coating, i.e., radiation hardened. The radiation exposure step 24 ensures that the entire surface area of ​​the sprayed fluid coating is uniformly exposed to the radiation 14, and no portion of the surface is selectively exposed to the radiation or selectively prevented from being exposed to the radiation, such as by masking the surface as used in photopatterning techniques.

[0049] Optionally, the coated substrate may be heated (in a "soft bake" step) after spread coating 22 and before radiation exposure 24. However, a heating step between spread coating step 22 and radiation exposure 24 is not required and can be omitted in certain exemplary methods.

[0050] After radiation exposure 24, the at least partially cured polymer coating (the "radiation cured" polymer coating) is exposed to an elevated temperature, for example, in an oven, as shown by the dashed line in FIG. 1C. The radiation cured polymer coating includes the solvent of the spray solution (e.g., up to 50, 60, 70, 75, or 80 weight percent or more of the solvent). The solvent can be removed by heating the radiation cured polymer coating at an elevated temperature in a "hard bake" step. The hard bake step 26 may be effective to remove the solvent from the radiation cured polymer coating, to further harden the polymer of the radiation cured polymer, or both. The hard bake 26 may include exposing the substrate having the radiation cured polymer coating to an elevated temperature for a period of time effective to remove the solvent from the radiation cured coating, to further harden the polymer of the radiation cured coating, or both. The time and temperature of exposure to the elevated temperature can be selected based on factors such as the thickness of the coating, the type of radiation curable polymer of the coating, and the desired final properties of the cured (fully cured) polymer blanket coating. An example of a useful temperature can range from 150 degrees Celsius to 400 degrees Celsius. An example of a useful time for the hard bake step can be at least 45 or 60 minutes, such as from 45 minutes to 120 minutes.

[0051] The cured polymer coating after the hard bake step may preferably have a relatively uniform thickness across the entire surface, for example in a thickness range of less than 6 microns, such as 3-5 microns thick.

[0052] The following table lists some specific examples of process features of the exemplary method as described. TIFF0007661608000002.tif116170

[0053] In comparison to photopatterning methods, the method 10 of Figures 1A and 1B does not include any "development" step or other step in which a portion of the applied spray coating (film) is not intended to be cured or removed from the substrate surface after being placed on the substrate surface. The method 10 of Figures 1A and 1B does not include a step of selectively exposing only a portion of the applied spray coating to radiation, while another portion of the applied spray coating is selectively shielded from the radiation (e.g., using a mask).

[0054] FIG. 3 shows a plan view of the top surface of an exemplary electrostatic chuck being described. In one example, the electrostatic chuck may have a diameter that may be, for example, 300 mm, 200 mm, or 450 mm. The surface of the electrostatic chuck includes gas inlets 417, earth pin openings ("passages") 418, a gas seal ring 419 around the periphery of the chuck surface, and lift pin openings ("passages") 420, each with its own gas seal ring (in FIG. 3, an outer circular structure around the lift pin passage 420) and a small gas inlet (not visible in FIG. 3) in the center of the chuck 421. Each earth pin opening 418 includes an optional gas seal ring (shown in FIG. 3 as a circular ring around the earth pin opening 418). A detailed view (inset 422 in FIG. 3) shows the circular protrusions 414. Gas seal ring 419, as well as the gas seal rings at lift pin opening 420 and earth pin opening 418, may be about 0.1 inches wide and have a height equal to the height of protrusion 414, such as about 3 microns to about 12 microns, for example about 6 microns, although other widths and heights are possible.

[0055] A first aspect disclosed herein includes a method of applying a blanket coated polymer coating to a surface of an electrostatic chuck, the method including applying a spray fluid to the surface of the electrostatic chuck to form a spray fluid coating over the entire surface, the spray fluid including a radiation curable polymer; exposing the entire surface of the spray fluid coating to radiation to form a radiation cured polymer coating; and heating the radiation cured polymer coating to an elevated temperature to remove solvent from the radiation cured polymer coating.

[0056] The second embodiment of the first embodiment, wherein the radiation curable polymer comprises a radiation curable epoxy polymer.

[0057] The third embodiment of the present invention is directed to the second embodiment, wherein the spray liquid comprises at least 75 weight percent organic solvent.

[0058] The fourth aspect of the second or third aspect, wherein the spray solution has a viscosity in the range of 3 to 9 centipoise when applied to the ceramic surface.

[0059] A fifth embodiment of any preceding embodiment, wherein the surface is at a temperature of less than 30 degrees Celsius when the spray liquid is applied to the surface.

[0060] A sixth embodiment of any preceding embodiment, comprising applying spray liquid to a surface by multiple spray paths, each spray path passing across the surface in an end-to-end direction, and all spray paths moving in the same direction from end to end.

[0061] A seventh embodiment of any preceding embodiment, comprising applying a spray solution to an entire surface and exposing the entire surface of the spray solution coating to radiation to form a radiation cured polymer coating, wherein the surface is not heated during application and curing or between application and curing.

[0062] The eighth embodiment of any preceding embodiment, comprising heating the radiation cured polymer coating to a temperature in the range of 150 to 400 degrees Celsius for a time period of at least 45 minutes.

[0063] A ninth embodiment of any preceding embodiment, comprising applying the spray coating at a thickness in the range of 3 to 5 microns.

[0064] A tenth aspect of any preceding aspect, wherein a surface of the electrostatic chuck consists essentially of ceramic.

[0065] An eleventh aspect of any preceding aspect, wherein a surface of the electrostatic chuck is made of ceramic.

[0066] A twelfth aspect of any preceding aspect, wherein the surface comprises a main region of ceramic, ceramic protrusions extending perpendicularly from the main region, and a continuous ceramic circumferential seal at an exterior region of the main region.

[0067] The thirteenth aspect of any preceding aspect, wherein the surface roughness is in the range of 0.01 to 10 microns (Ra).

[0068] The fourteenth embodiment of any preceding embodiment, wherein the radiation curable polymer is electrically conductive.

[0069] In a fifteenth aspect, an electrostatic chuck includes a coating applied by the method of any of the preceding aspects.

Claims

1. 1. A method for applying a blanket coated polymeric coating to a surface of an electrostatic chuck, comprising: applying a solution to the surface of the electrostatic chuck to form a solution coating over the surface, the solution comprising a radiation curable polymer; exposing the entire surface of the solution coating to radiation to form a radiation cured polymer coating; heating the radiation cured polymer coating to an elevated temperature to remove solvent from the radiation cured polymer coating; Including, The method, wherein heating the radiation cured polymer coating comprises heating the radiation cured polymer coating to a temperature in the range of 150 to 400 degrees Celsius for at least 45 minutes.

2. 10. The method of claim 1, further comprising applying the solution to the surface in a plurality of passes, each pass passing across the surface and all passes moving in the same direction across the surface.

3. applying the solution to the entire surface; exposing the entire surface of the solution coating to radiation to form a radiation cured polymer coating; Further comprising: The method of claim 1 , wherein the surface is not heated during application and exposure or between said application and said exposure.

4. A method for applying a blanket coated polymeric coating to a surface of an electrostatic chuck, comprising the steps of: applying a solution to the surface of the electrostatic chuck to form a solution coating over the entire surface, the solution comprising a radiation curable polymer, and applying the solution to the surface using multiple passes, each pass passing across the surface and all passes moving in the same direction across; exposing the entire surface of the solution coating to radiation to form a radiation cured polymer coating; heating the radiation cured polymer coating to an elevated temperature to remove solvent from the radiation cured polymer coating; A method comprising:

5. A method for applying a blanket coated polymeric coating to a surface of an electrostatic chuck, comprising the steps of: applying a solution to the surface of the electrostatic chuck to form a solution coating over the surface, the solution comprising a radiation curable polymer; exposing the entire surface of the solution coating to radiation to form a radiation cured polymer coating; heating the radiation cured polymer coating to an elevated temperature to remove solvent from the radiation cured polymer coating; Including, The surface is The main area of ​​ceramics, a ceramic protrusion extending perpendicularly from said main region; and providing a continuous ceramic circumferential seal at an exterior region of said main region.

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