JP2012507409A - Monolithic linear polishing sheet - Google Patents

Abstract

  The chemical mechanical abrasive article may be a single continuous layer having an abrasive surface, the layer being an elongated, substantially rectangular sheet having a width and a length of at least four times the width. Forming the abrasive article includes depositing a liquid precursor on the movable belt, curing the liquid precursor at least partially while remaining on the movable belt to form an abrasive layer, and polishing from the belt. Removing the layer.

Description

  The present disclosure relates to chemical mechanical polishing.

  Integrated circuits are typically formed on a substrate by sequentially depositing a conductive layer, a semiconductive layer, or an insulating layer on a silicon wafer. One fabrication step includes depositing a filler layer over the patterned stop layer and planarizing the filler layer until the stop layer is exposed. For example, a conductive layer can be filled in a trench or hole in the insulating layer. After planarization, the portions of the conductive layer that remain between the raised patterns of the insulating layer form vias, plugs, and wiring that provide conductive paths between the thin film circuits on the substrate. Planarization can also be used to provide a flat surface for photolithography.

  Chemical mechanical polishing (CMP) is one accepted planarization method. Usually, this planarization method requires that the substrate be mounted on a carrier or polishing head. The carrier head applies the exposed surface of the substrate to the polishing pad and provides a controllable load or pressure on the substrate. A polishing liquid such as an abrasive slurry is supplied to the surface of the polishing pad.

  In one type of polishing system, the polishing pad is a linear sheet that progressively advances across the platen.

  In one aspect, the chemical mechanical abrasive article is a single continuous layer having an abrasive surface, the layer being an elongated substantially square sheet having a width and a length of at least four times the width.

  Implementations can include one or more of the following features. The layer can be a polyurethane, such as a porous polyurethane. The layer can have a thickness of about 30-50 mils. The polishing surface can include a plurality of grooves that partially penetrate the polishing pad rather than completely. These grooves can have a depth of about 15-30 mils. At least a portion of the layer can be wound into a roll. The layer can have a length of about 20-30 feet and a width of about 2-4 feet.

  In another aspect, a chemical mechanical abrasive article extends between the first and second sheet portions and the lengths of the first and second sheet portions to connect the first sheet portion and the second sheet portion. Including a connecting window. Each sheet portion consists of a single continuous layer having an abrasive surface, each sheet portion being an elongated substantially square sheet having a width and a length of at least four times the width.

  In another aspect, a chemical mechanical polishing assembly comprises a feed roller, a take-up roller, a polishing end having a first end wound on the feed roller and a second end wound on the take-up roller. Sheet. An abrasive sheet consists of a single continuous layer having an abrasive surface, which is an elongated, substantially rectangular sheet having a width and a length of at least four times the width.

  In another aspect, a method of forming an abrasive article includes depositing a liquid precursor on a movable belt and at least partially curing the liquid precursor while on the movable belt to form an abrasive layer. And removing the abrasive layer from the belt.

  Implementations can include one or more of the following features. The liquid precursor can be deposited on a carrier sheet supported on a belt, such as a polyethylene terephthalate polyester film. The polishing layer can be removed from the carrier sheet. The top and bottom surfaces of the polishing layer can be ground. At least partially curing the liquid precursor can include heating. The abrasive sheet can be fully cured after removal from the belt. The abrasive sheet can be compressed, for example, passed between pinch rollers. Grooves can be formed in the polishing sheet. The edge of the abrasive sheet can be cut off.

  Advantages can include the following. The polishing layer can be made thicker without reducing the length of the sheet wrapped around the feed roller, thus increasing pad life. Light transmission through the window in the polishing sheet can be improved.

  Other features and advantages will become apparent from the following description, including the drawings and the claims.

1 is a schematic exploded perspective view of a chemical mechanical polishing (CMP) apparatus. It is a top view of the CMP apparatus of FIG. FIG. 2 is a top plan cutaway view of a first polishing station of the CMP apparatus of FIG. 1. It is a schematic exploded perspective view of a square platen and a polishing cartridge. It is a schematic perspective view of the polishing cartridge attached to the square platen. It is a schematic perspective cutaway view of a linear polishing sheet. It is a schematic side cross-sectional view of one mounting form of an abrasive sheet. It is a schematic side cross-sectional view of another mounting form of an abrasive sheet. It is a schematic side cross-sectional view of another mounting form of an abrasive sheet. It is a schematic side view of the feed roller of the polishing cartridge. It is a schematic perspective cutaway view of another mounting form of the polishing sheet. It is a schematic side view of the machine which manufactures the abrasive sheet of FIG. It is a schematic top view of one mounting form of an abrasive sheet.

  With reference to FIGS. 1 and 2, one or more substrates 10 are polished by a chemical mechanical polishing apparatus 20. A description of a similar polishing apparatus can be found in US Pat. No. 6,244,935. The patent description is incorporated by reference. The polishing apparatus 20 includes a mechanical base 22 and supports on a table 23 a series of polishing stations including a first polishing station 25a, a second polishing station 25b, and a final polishing station 25c, and a transfer station 27.

  Each polishing station includes a rotatable platen. At least one of the polishing stations, such as the first station 25a, includes a polishing cartridge 102 mounted on a rotatable square platen 100. The abrasive cartridge 102 includes a sheet or belt of abrasive material that is linearly advanceable. The remaining polishing stations, e.g., second polishing station 25b and final polishing station 25c, may include "standard" circular polishing pads 32 and 34, respectively, where circular polishing pads 32 and 34 are each circular. It is attached so as to adhere to the platen 30. Each platen can be connected to a platen drive motor that rotates the platen.

  Each polishing station 25a, 25b, and 25c also includes a slurry delivery outlet, a pad rinsing system (which can be a combined slurry / rinsing arm 52 protruding above the associated polishing surface), and a pad conditioner device 40. Including.

  A rotatable multi-head carousel 60 is supported on the polishing station by a central post 62 and is rotated about a carousel axis 64 by a carousel motor assembly (not shown). The carousel 60 can include four carrier head systems mounted on the carousel support plate 66 at equal angular intervals around the carousel axis 64. Three of the carrier head systems receive and maintain the substrate and polish the substrate by pressing against the polishing sheet at station 25a and the polishing pads at stations 25b and 25c. One carrier head system receives a substrate from the transfer station 27 and delivers the substrate to the transfer station 27.

  Each carrier head system includes a carrier or carrier head 80. The carrier drive shaft 78 connects a carrier head rotation motor 76 (shown by removing a quarter of the carousel cover) to the carrier head 80 so that each carrier head rotates independently about its own axis. can do. Further, each carrier head 80 independently vibrates laterally in a radial slot 72 formed in the carousel support plate 66.

  Referring to FIGS. 3A, 3B, and 3C, the polishing cartridge 102 is removably secured to the square platen 100 of the polishing station 25a. The polishing cartridge 102 includes a feed roller 130, a take-up roller 132, and a generally straight sheet 110 of polishing pad material (which can be considered to form a polishing belt or net). The length of the abrasive sheet (when completely unrolled from the roller) is significantly greater than the width of the abrasive sheet. The unused or “new” portion 120 of the polishing sheet is wound around the feed roller 130 and the used portion 122 of the polishing sheet is wound around the take-up roller 132. A square exposed portion 124 of the polishing sheet used to polish the substrate extends between the used portion 122 and the unused portion 120 so as to cover the upper surface 140 of the square platen 100.

  The square platen 100 is rotated (indicated by the phantom arrow “A” in FIG. 3A) to rotate the exposed portion of the polishing sheet, thereby causing relative movement between the substrate and the polishing sheet during polishing. Can be provided. During the polishing operation, the polishing sheet can be advanced (indicated by phantom arrow “B” in FIG. 3A) to expose unused portions of the polishing sheet. As the abrasive material advances, the abrasive sheet 110 is unwound from the feed roller 130, passes through the upper surface of the square platen, and is taken up by the take-up roller 132.

  Referring to FIG. 4, the abrasive sheet 110 includes an abrasive layer having an abrasive surface 112, and a leading end 160 and a terminating end 162 that extend beyond the abrasive layer (the polishing surface 112 thus extends to the end of the abrasive sheet). Does not extend). The tip and end can be made of a material that is more flexible than the polishing layer and optionally has a lower compressibility. The front end portion 160 and the end end portion 162 can be attached to the feed roller 130 and the take-up roller 132 by tape or pressure sensitive adhesive on the back surface of the front end portion. A liner that can be peeled over the tape or adhesive can be placed and removed before attaching the abrasive sheet 110 to the roller.

  The polishing layer can be made of porous polyurethane, and the tip and end can be made of a thin material that is difficult to tear, such as polyethylene terephthalate. The polishing layer can be opaque, while the tip and end can be transparent. Information such as a part number, a material type, a lot number, or a polishing layer length can be printed or embossed on the front end portion 160 and the end end portion 162.

  A groove can be formed in the polishing surface 112 across the entire width across the direction of travel of the sheet. These grooves can be approximately half the depth of the polishing layer, for example, 18-20 mils deep. The grooves can have a uniform width and pitch, for example, have a width of about 1 millimeter and are spaced about 2-3 millimeters apart. Referring to FIG. 9, the groove 128 can stop before the edge of the polishing layer. Such a groove configuration can improve the difficulty of tearing the polishing pad.

  The backing layer 116 can be about 5 mils thick. The abrasive layer can be about 20-30 feet long, such as 20-25 feet long, and can be 20-30 inches wide, such as about 28 inches wide. The tip 160 and end 162 have the same width as the polishing layer and can be about 6 feet long.

  Referring to FIG. 5A, in one implementation, the abrasive sheet includes a backing layer 116 and an abrasive layer 114 formed on the backing layer 116. In this implementation, the backing layer 116 can be a continuous sheet that spans the polishing layer 114. In the lateral direction (perpendicular to the length of the sheet and the direction of travel), the wide edges 164 (along the length of the sheet) of the polishing layer 114 and the backing layer 116 are such that the polishing layer and the backing layer 116 have the same width. Can be matched. In contrast, in the longitudinal direction (parallel to the sheet length and direction of travel), the backing layer 116 extends beyond the narrow edge 166 (the edge across the width of the sheet) of the polishing layer 114, and the tip A portion 160 and an end portion 162 are provided. In the region of the tip 160 and end 162, the upper surface of the backing layer 116 can be the outermost surface, i.e., there are no other layers on the backing layer 116. As described above, information such as a part number, a material type, a lot number, or a polishing layer length can be printed or embossed on the tip portion 160 and the end portion 162.

  The abrasive layer 114 can be a porous polyurethane, and the backing layer 116 can be a thin, flexible, generally incompressible fluid impermeable sheet, such as polyethylene terephthalate. The backing layer 116 can be transparent. The polyurethane layer can be 35-40 mils thick. The polishing layer 114 can be placed as a single continuous unbroken layer. Alternatively, the polishing layer 114 can be lined with adjacent strips, eg, 2-4 feet long.

  The abrasive layer 114 can be secured to the upper surface of the backing layer 116 by an adhesive 170, such as a pressure sensitive adhesive layer. For example, the polishing layer 114 and the backing layer 116 can be fabricated separately and then bonded together. Alternatively, the polishing layer 114 can be adhered to the backing layer 116 without the use of an adhesive. For example, a liquid precursor of the polishing layer can be dispensed onto the backing layer 116 and cured, thereby forming the polishing layer 114 that adheres to the backing layer 116.

  Referring to FIG. 5B, in another implementation, the abrasive sheet includes a backing layer 116 and an abrasive layer 114 formed on the backing layer 116, but the tip 160 and the termination 162 are on the backing layer 116. A separate piece 172 joined. In this implementation, the backing layer 116 can be a continuous sheet having edges that span the polishing layer 114 and are coextensive with the polishing layer 114.

  The polishing layer 114 can be porous polyurethane. The backing layer 116 may be softer than the polishing layer or less compressible than the polishing layer, and may be transparent or opaque. For example, the backing layer can be a soft subpad such as a fibrous mat impregnated with urethane, or can be a generally incompressible layer such as polyethylene terephthalate. The separate piece 172 may be a sheet that is thin, flexible, difficult to tear and generally impermeable to fluid, such as polyethylene terephthalate.

  As discussed above, the abrasive layer 114 can be secured to the backing layer with or without an adhesive. The tip and end piece 172 can be secured to the backing layer 116 with a butt joint and thin tape 174 on the underside of the abrasive sheet.

  Referring to FIG. 5C, in another implementation, the abrasive sheet includes an abrasive layer 114 but no backing layer, and the tip 160 and end 162 are separate pieces joined to the abrasive layer 114. is there. The polishing layer 114 can be porous polyurethane. The tensile strength of the polishing layer 114 can be about 22 MPa (greater than 3000 psi). This should exceed the average stress applied during vacuum chucking of the mesh onto the platen (approximately 14 psi) or the average stress applied during advancement of the mesh (approximately 100 psi).

  The separate piece 172 may be a thin, flexible, difficult to tear, generally incompressible, fluid-impermeable sheet such as polyethylene terephthalate. The tip and end pieces 172 can be joined to the polishing layer 114 by a thin tape 174 on the underside of the polishing sheet.

  In each of the above implementations, the abrasive layer does not extend to the edge of the abrasive sheet, so this abrasive sheet uses less abrasive layer material compared to an abrasive sheet having an abrasive layer throughout its length, Therefore, it can be manufactured at a lower cost.

  Referring to FIGS. 3B and 6, the feed roller 130 and the take-up roller 132 should be slightly longer than the width of the abrasive sheet 110. Rollers 130 and 132 may be plastic or metal cylinders that are slightly longer than the width of the abrasive sheet and have a diameter of about 2 ″. Opposing end surfaces 134 of feed roller 130 (only the feed roller is shown in FIG. 6). , Each take-up roller will be similarly constructed) may include a recess 136 that engages a support and drive mechanism on the platen, eg, one end face may include a keyed slot. An alignment pin can be fitted in the slot, and the other end face can include a keyed star pattern in which the drive gear fits, and both ends of each roller. Can include a circular flange 138. The flange 138 protrudes above the surface of the roller to maintain the abrasive sheet in place and provides a polishing sheet from either side of the roller. To prevent the sliding off.

  The tip and end can be more flexible than the polishing layer and can therefore be more easily manipulated and therefore more easily placed on the roller. Furthermore, since the tip and end portions can be more flexible than the polishing layer, the tip and end portions can be wound more tightly on the roller. This can reduce the diameter of the roller, thus reducing the volume required by the cartridge or storing more abrasive material in the cartridge.

  Referring to FIG. 7, in another implementation, the abrasive sheet is a single layer, specifically having an abrasive surface 112 but no backing layer or carrier film, and having a leading or trailing end. It is a non-polishing polishing layer 114. The polishing layer 114 is a continuous monolithic layer. The entire length of the polishing layer between the feed roller and the take-up roller is an uninterrupted seamless portion, for example, there is no adhesive connection between separate pieces, and the entire polishing layer 114 has a generally uniform composition. Is. In some implementations, the polishing layer is formed without heat-based molding of separate pieces (such molding produces a slightly different area that is consistent where the molding occurs). And the polishing layer 114 can be homogeneous enough to eliminate such areas). The polishing layer 114 has sufficient bonding force and mechanical integrity to prevent tearing under the mechanical force applied at typical CMP processing conditions. The polishing layer 114 can be porous polyurethane. The length of the polishing layer 114 can be at least six times greater than the width. For example, the polishing layer 114 can be about 2-3 feet wide, such as 2.5 feet wide, and 30-40 feet long. Although shown in FIG. 7 in a flat state, in use, the end portion of the polishing sheet 114 is wound around the winding and feeding rollers as shown in FIG. 3B, for example. . The ratio of the length and width of the abrasive sheet can be at least 4: 1, for example 12: 1.

  The polishing layer 114 can be about 30-50 mils thick. Since the backing layer and the adhesive that would keep the backing layer in the abrasive layer are eliminated, the abrasive layer can be made thicker and still have the same length without increasing the diameter of the abrasive magazine. The abrasive sheet can be wound on a spindle. Since the polishing layer 114 is thicker, the number of substrates polished per unit length of the polishing sheet can be increased, thus increasing the pad life. For example, having a 50 mil thick abrasive layer as compared to an abrasive sheet having a 40 mil thick abrasive layer, a 5 mil thick backing layer, and a 5 mil thick adhesive (but not a backing layer or adhesive) A polishing sheet that does not have a capacity should increase by about 20-33%. Within the polishing surface 112 of the polishing layer 114, a groove having a depth of, for example, about 15-30 mils, for example, approximately half the thickness of the polishing layer, is formed through the polishing layer pad partially but not completely. be able to.

  If a window stripe is formed in the abrasive sheet, each of the two portions on either side of the stripe can be a single continuous layer. The side of the window can be molded into the side of the polishing layer portion.

  Referring to FIG. 8, a method for making such a monolithic abrasive sheet is to deposit a liquid precursor 200 on a movable belt 210. The layer of liquid precursor on the belt 210 can be subjected to a first curing process, for example, the belt and layer are passed through a furnace 212 or other heat source to at least partially cure the precursor and become semi-solid. Sheet 202. The semi-solid sheet 202 can then be removed from the belt and passed between pinch rollers 214, 216 that compress the sheet to the desired thickness. Further, a protrusion on one of the pinch rollers 216 can cut a groove into the surface of the semi-solid sheet 202. Sheet 202 can then be subjected to a second curing process, such as additional heat, such as second furnace 220, to cure to the final desired hardness. The edges of the sheet 202 can be cut to provide a uniform width abrasive sheet, and if necessary, the abrasive sheet can be removed, for example, with a grinder or sheet to remove burrs or other defects. Can be smoothed and / or thinned by passing between the top and bottom portions of the blade between the sharpening blades. A similar process can be used to create the polishing layer 114 for the implementation of FIG. 5C.

  In some implementations, a polyurethane precursor material is poured onto the carrier sheet (eg, the carrier sheet is placed on a movable belt or on spaced rollers so that the carrier sheet provides a movable belt-like surface. The abrasive sheet can be formed by subjecting the precursor to a first curing step. The carrier sheet can be peeled off before or after the final curing step. The abrasive sheet can then be scraped on both sides, ground and / or polished with sand to adjust the pad thickness and remove any cured crust layer.

  Grooves can be formed on the cured abrasive sheet using a cutting tool such as a knife blade. If the grooves are formed by engraving with a patterned roller and a subsequent curing step, the grooves will have a smooth or non-porous surface layer in the grooves by selecting the appropriate degree of compression. (In contrast, the polishing surface itself can be porous, and the groove formed in the porous pad with a knife has a porous wall and bottom). In such cases, the waste or abrasive debris is less likely to remain trapped in the groove, thus reducing the potential for defects, such as scratches.

  Returning to FIGS. 3A, 3B, and 3C, the rectangular platen 100 has a generally flat rectangular upper surface 140 that is bounded by a feed edge 142, a take-up edge 144, and two parallel lateral edges 146. including. A groove 150 (shown in phantom in FIGS. 3A and 3C) is formed in the upper surface 140. The groove 150 can be a generally square pattern extending along the edges 142, 144, 146 of the top surface 140. Alternatively, the vacuum groove 150 can be circular and about 29 "in diameter, and the polishing area can be described by the movement of the head and platen contained within the area indicated by the dashed line 150 in FIG. 3A. .

  A passage through the platen 100 connects the groove 150 to a vacuum source. When the passage is evacuated, the exposed portion 124 of the abrasive sheet 110 is vacuum chucked to the upper surface 140 of the platen 100. This vacuum chuck helps to prevent lateral forces caused by friction between the substrate and the polishing sheet during polishing from separating the polishing sheet from the platen. Optionally, the central region 148 of the top surface 140 can be free of grooves to prevent the polishing sheet from potentially deflecting into the grooves to interfere with polishing uniformity.

  In order to mitigate the impact of the substrate on the abrasive sheet, a compressible backing pad (not shown) can be placed on the upper surface of the platen. Further, the platen 100 can include a shim plate (not shown). Different thickness shim plates can be attached to the platen to adjust the vertical position of the upper surface of the platen. A compressible backing pad can be attached to the shim plate.

  In some implementations, the square platen 100 also includes four retaining flanges 156 that maintain the feed roller 130 and the take-up roller 132 at the feed edge 142 and the take-up edge 144, respectively. Each retaining flange 156 includes a protrusion or detent that can engage a corresponding feature on the end of the roller 130 or 132.

  Rollers 130 and 132 are more than upper surface 140 such that when the entire abrasive sheet is wound on either roller, the abrasive sheet remains in contact with platen feed edge 142 and take-up edge 144. Can be positioned below. This helps provide a seal between the abrasive sheet and the square platen when the passage is evacuated and the abrasive sheet is vacuum chucked to the platen. Furthermore, in order to prevent abrasion of the lower surface of the polishing sheet when the polishing sheet passes through the platen, the feeding edge portion 142 and the winding edge portion 144 of the platen are rounded.

  A transparent strip 118 can be formed along the length of the abrasive sheet 110. The transparent strip can be positioned in the center of the sheet and can be about 0.6 inches wide. With reference to FIGS. 5A and 5B, a transparent strip 118 can be formed by removing the top layer 114 from this region of the transparent backing layer 116. With respect to FIG. 5C, the transparent strip 118 can be formed by molding a window into the polishing layer 114. The transparent strip 118 can be aligned with an opening or transmission window 154 in the square platen 100 to provide optical monitoring of the substrate surface for endpoint detection.

  Referring again to FIGS. 3A, 3B, and 3C, in operation, the exposed portion 124 of the abrasive sheet 110 is vacuum chucked to the square platen 100 by evacuating the passage. The substrate is lowered by the carrier head 80 into contact with the polishing sheet 110, and both the platen 100 and the carrier head 80 rotate to polish the exposed surface of the substrate. After polishing, the substrate is lifted from the polishing pad by the carrier head. The vacuum on the passage 152 is removed. The polishing sheet is advanced to expose a new section of the polishing sheet. The abrasive sheet is then vacuum chucked to a square platen and the new substrate is lowered and contacts the abrasive sheet. Therefore, the polishing sheet can be gradually advanced between each polishing operation. If the polishing station includes a cleaning device, the polishing sheet can be washed between each polishing operation.

  The amount by which the sheet can be advanced depends on the desired polishing uniformity and the characteristics of the polishing sheet, but should be on the order of 0.05 to 1.0 inch, for example 0.4 inch, per polishing operation. Assuming that the exposed portion 124 of the polishing sheet is 20 inches long and the polishing sheet is advanced 0.4 inches after each polishing operation, the entire exposed portion of the polishing sheet is Exchanged.

  In another embodiment, the abrasive sheet can be made of an abrasive layer disposed on the carrier layer, such as a polyethylene terephthalate polyester film, such as a Mylar sheet. In some implementations, the abrasive sheet can be formed by pouring a polyurethane precursor material onto a carrier layer (eg, a carrier layer on a movable belt) as discussed above. However, rather than removing the carrier layer, the polishing layer remains on the carrier layer to form the final polishing sheet. In this case, the grinding and surface finishing operations that adjust the thickness or roughness of the polishing layer are performed only on the upper surface. In some implementations, the initial carrier layer is removed, grinding and surface finishing operations are performed, and the abrasive layer can then be attached to a new carrier layer for the final abrasive sheet.

  The present invention is not limited to the illustrated and described embodiments. On the contrary, the scope of the present invention is defined by the appended claims.

Claims (15)

  A chemical mechanical abrasive article comprising a single continuous layer having an abrasive surface, wherein the layer is an elongated, substantially rectangular sheet having a width and a length of at least four times the width.   The article of claim 1, wherein the layer comprises porous polyurethane.   The article of claim 1, wherein the polishing surface comprises a plurality of grooves that partially penetrate the polishing pad rather than completely.   4. The article of claim 3, wherein the layer has a thickness of about 30-50 mils and the groove has a depth of about 15-30 mils.   The article of claim 1, wherein at least a portion of the layer is wound into a roll.   The article of claim 1, wherein the layer has a length of about 20-30 feet.   The article of claim 1, wherein the layer has a width of about 2 to 4 feet. First and second sheet portions, each sheet portion consisting of a single continuous layer having an abrasive surface and having a width and a length of at least four times said width substantially rectangular First and second sheet portions that are sheets;
A chemical mechanical abrasive article extending over the length of the first and second sheet portions and comprising a window connecting the first sheet portion and the second sheet portion. A feed roller;
A winding roller;
A polishing sheet having a first end wound around the feed roller and a second end wound around the take-up roller, comprising a single continuous layer having an abrasive surface, the layer comprising And a polishing sheet that is an elongated substantially rectangular sheet having a width and a length of at least four times the width. Depositing a liquid precursor on the movable belt;
Curing the liquid precursor at least partially while remaining on the movable belt to form a polishing layer;
Removing the abrasive layer from the belt.   The method of claim 10, wherein depositing the liquid precursor comprises depositing the liquid precursor on a carrier sheet supported on the belt.   The method of claim 11, further comprising removing the polishing layer from the carrier sheet.   The method of claim 12, further comprising grinding a top surface and a bottom surface of the polishing layer.   The method of claim 10, further comprising fully curing the abrasive sheet after removing the abrasive sheet from the belt.   The method of claim 10, further comprising compressing the abrasive sheet.

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