Method for producing polishing pad

Abstract

The present invention provides a method for producing a polishing pad which is equipped with an end point detection window (window member) and in which adhesion between a back surface of the window member and an adhesion surface of a second sheet is excellent. Disclosed is a method for producing a polishing pad that includes a first sheet having a first through hole, a second sheet having a second through hole, and a window member, wherein the first sheet has a polishing surface for polishing an object to be polished, the second sheet is bonded to a surface of the first sheet on the opposite side from the polishing surface, an outer peripheral part of the second through hole is formed so as to be covered by an outer peripheral part of the first through hole, and the window member is disposed inside the first through hole and on the second sheet such that the uppermost part of the window member is lower than the polishing surface. The method comprises: a step for preparing the polishing pad; and a step for disposing a spacer of a prescribed thickness on a press lower platen in the periphery of the polishing pad and pressing the polishing pad with a press.

Description

Polishing pad manufacturing method

[0001] The present invention relates to a method for manufacturing a polishing pad, and more particularly to a method for manufacturing a polishing pad for chemical mechanical polishing (CMP) having an optically transparent region.

[0002] Chemical mechanical polishing (hereinafter referred to as "CMP") is used in semiconductor manufacturing processes (particularly, planarization of an interlayer insulating film in a multilayer wiring formation process, formation of a metal plug, or formation of a buried wiring). CMP is applied to semiconductor manufacturing processes (particularly, planarization of an interlayer insulating film in a multilayer wiring formation process, formation of a metal plug, formation of a buried wiring, etc.).

[0003] In recent years, semiconductor devices have become increasingly multilayered and highly precise, necessitating further improvements in semiconductor device yield and throughput. This demands polishing pads to be defect-free and have high planarization characteristics without dishing. To achieve these demands, it is necessary to detect when the desired surface characteristics and flatness are reached. Optical detection methods are widely used because they enable accurate detection. For example, in this method, a light-transmitting window for detecting the polishing endpoint is formed in at least a portion of the polishing layer constituting the polishing pad. Light is irradiated onto the processed surface through this window, and the reflected light from the processed surface is observed to determine the polishing state. This allows for in situ detection of the polishing endpoint, thereby preventing a decrease in yield due to overpolishing.

[0004] As a pad having a window for endpoint detection, there is known a polishing pad of a type in which through holes are drilled in multiple layers and a window member is fitted into the through holes (insertion type) (Patent Documents 1 to 5). Also, as a manufacturing method of a polishing pad with a window member, there is known a method in which a window member is inserted and integrated at the stage of forming the polishing layer (integration type), and a hole is drilled in an adhesive layer or cushion layer so as to match the position of the window member of the polishing layer obtained, and then the two layers are bonded together (Patent Document 6).

[0005] Japanese Patent Application Laid-Open No. 2004-260156 Japanese Patent Application Laid-Open No. 2021-136288 Japanese Patent Application Laid-Open No. 2020-516474 Japanese Patent Application Laid-Open No. 2023-105842 Japanese Patent Application Laid-Open No. 2019-93543 Japanese Patent Application Laid-Open No. 2022-149504

[0006] The manufacturing methods of Patent Documents 1 to 5 are so-called insertion-type manufacturing methods, in which a window member is adhesively fixed onto a support layer that is bonded to the polishing layer. In this case, there is a problem that slurry leakage is likely to occur during the CMP process due to a gap between the polishing layer and the window member. For example, in Patent Document 1, a hole for fitting the window member is punched into the polishing layer, double-sided tape is attached to the cushion layer, and the polishing layer and cushion layer are bonded together via the double-sided tape. A portion of the cushion layer corresponding to the hole for fitting the window member is then pierced through the punched hole, and the window member is then fitted. However, simply fitting the window member may leave air between the window member and the double-sided tape, which may allow slurry to seep into the areas that are not bonded together, resulting in peeling of the window member. To address this problem, Patent Document 3 describes a method of preventing leakage by applying a hot-melt adhesive to the back surface of the window member and also using a hot-melt adhesive on the support layer and polishing layer to thermally fuse the window member and the support layer. In this case, although leakage can be prevented, there is a risk of a decrease in light transmittance due to the two-layered light-transmitting portion, or of foreign matter adhering to the exposed adhesive surface, resulting in a decrease in light transmittance. In Patent Document 4, in order to prevent the window member from peeling off from the polishing layer, the back surface of the polishing layer around the window member is ground to form a recessed flange portion, and this flange portion is then adhesively fixed to the polishing layer and cushion layer. In this case, if the polishing layer is soft, the surface of the polishing layer where the flange portion is present becomes harder than the other polishing surfaces, increasing the rigidity only around the window portion, which may cause uneven wear and scratch the polished object. Similarly, Patent Document 5 discloses that water leakage is suppressed by providing a compressed region in the support layer around the window member. In this case, the rigidity only around the window portion increases, which may cause uneven wear and scratch the polished object. Furthermore, in conventional polishing pads such as those described in Patent Documents 1 to 5, through holes are formed using a punch or the like. For example, Patent Document 3 describes cutting second and third through holes within the first through hole using a guide member. Patent Document 2 describes forming through holes using a punch. As described above, conventionally, through holes have to be manually aligned and punched out, which can lead to human error and requires time for alignment, resulting in low processing efficiency and unstable quality.On the other hand, the method of Patent Document 6 is a so-called integrated type, but it involves bonding a first sheet with an embedded window member (the window member is integrally formed as part of the first sheet) to an adhesive layer or cushion layer with a through-hole formed at a position corresponding to the window member of the first sheet so that the window member and the through-hole are aligned. Because the pad and the window member are contiguous and on the same plane, the window member may reflect light from the illumination, potentially resulting in failure to obtain position information for the window member. Reducing the ambient brightness to prevent reflections can make it difficult to identify the position of the window member. Furthermore, the method of Patent Document 6 can be prone to errors in reading position information, including information about the contour and center position of the end point detection window, or errors in reading the center position of the end point detection window and the center position of the hole to be formed. These errors can cause misalignment between the window member and the through-hole during bonding, preventing commercialization.

[0007] The present invention has been made in consideration of the above points, and has as its first object to provide a method for manufacturing a polishing pad with an endpoint detection window (with a window member) that improves adhesion between the window member and the polishing pad and is less susceptible to uneven wear. The second object of the present invention is to provide a method for manufacturing a polishing pad that can be manufactured simply and efficiently while reducing the amount of manual operation required by humans.

[0008] As a result of intensive research into the first problem, the present inventors have discovered that by pressing the polishing pad with a press using a spacer of a predetermined thickness, adhesion between the back surface of the window member and the adhesive surface of the second sheet is improved and uneven wear is less likely to occur, the present invention has been completed. The polishing pad includes a first sheet having a first through hole, a second sheet having a second through hole, and a window member, wherein the first sheet has a polishing surface for polishing an object to be polished, the second sheet is bonded to the surface of the first sheet opposite to the polishing surface, the second through hole is formed such that, when the first sheet is viewed in the thickness direction from the polishing surface side, the outer periphery of the second through hole is covered by the outer periphery of the first through hole, and the window member is disposed within the first through hole and on the second sheet so that, when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface, the uppermost part of the window member is lower than the polishing surface. Furthermore, as a result of intensive research into the second problem, the inventors discovered that by using a colored film to identify the position of the first through hole, a polishing pad with an endpoint detection window can be efficiently manufactured, and completed the present invention.

[0009] [1] A polishing pad comprising a first sheet having a first through hole, a second sheet having a second through hole, and a window member, wherein the first sheet has a polishing surface for polishing an object to be polished, the second sheet is bonded to a surface of the first sheet opposite to the polishing surface, the second through hole is formed such that, when the first sheet is viewed in the thickness direction from the polishing surface side, the outer periphery of the second through hole is covered by the outer periphery of the first through hole, and the window member is disposed within the first through hole and on the second sheet so that, when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface, the uppermost part of the window member is lower than the polishing surface, the method comprising the steps of: preparing the polishing pad; and placing the polishing pad on a lower platen of a press having an upper platen and a lower platen, placing spacers of a predetermined thickness on the lower platen around the polishing pad, and pressing the polishing pad with the press, The manufacturing method according to [1], wherein the thickness S of the spacer is within the range of the thickness of the second sheet≦S≦(H−Tave1), and the pressing pressure is 0.8 MPa or less. (Here, S is the thickness of the spacer, H is the thickness of the polishing pad before pressing, and Tave1 is the average depth from the polishing surface to the upper surface of the window member before pressing.) [2] The manufacturing method according to [1], comprising pressing the polishing pad with a press machine so that |Tave1−Tave2|≦40 μm. (Here, Tave1 is the average depth from the polishing surface to the upper surface of the window member before pressing, and Tave2 is the average depth from the polishing surface to the upper surface of the window member after pressing.)) [3] The step of preparing a polishing pad includes the following steps: a step of preparing a first sheet having a polishing surface and a surface opposite to the polishing surface (opposite surface), and a second sheet having an adhesive on at least one surface of the sheet; a step of forming a first through hole penetrating the first sheet in a thickness direction from the polishing surface to the opposite surface; a step of bonding the first sheet and the second sheet together so that the opposite surface of the first sheet and the surface of the second sheet having the adhesive face each other; a step of arranging a film in the first through hole of the first sheet to which the second sheet is bonded, wherein the film is a colored film and has substantially the same shape as the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and a step of acquiring position information of the first through hole. the first sheet is viewed in the thickness direction from the polishing surface side, and the second through hole is formed in such a way that an outer periphery of the second through hole is covered with an outer periphery of the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side, based on the acquired position information, and the second through hole is formed so that an outer periphery of the second through hole is covered with an outer periphery of the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side, and the second through hole is formed in such a way ...[5] The manufacturing method according to [3] or [4], further comprising the step of preparing a cutting device including: a photographing unit that photographs the first sheet from above the polished surface of the first sheet when the polished surface of the first sheet is placed on top; a control unit that identifies the position of a first through hole from the image photographed by the photographing unit and, based on information about the identified position of the first through hole, commands the formation of a second through hole that penetrates the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polished surface side; and a hole forming unit that forms the second through hole in accordance with the command of the control unit, wherein the step of acquiring position information includes the control unit identifying the position of the first through hole from the image photographed by the photographing unit. [6] The manufacturing method according to [5], further comprising the step of preparing a cutting device including: a photographing unit that photographs the first sheet from above the polished surface of the first sheet when the polished surface of the first sheet is placed on top; [7] The manufacturing method according to [5] or [6], wherein the step of forming the second through hole includes forming a second through hole that passes through the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side, based on the acquired position information of the first through hole, by the hole forming unit. [8] The manufacturing method according to any of [3] to [7], wherein the step of forming the second through hole includes forming the second through hole based on the position information of the first through hole so that the center of the first through hole and the center of the second through hole are substantially the same when the first sheet is viewed in the thickness direction from the polishing surface side. [9] The manufacturing method according to any one of [3] to [8], further comprising the steps of: acquiring information on positions (equidistant positions) that are equidistant from the centers of all of the first through holes when the first sheet is viewed in the thickness direction from the polishing surface side based on the position information of the first through holes; and cutting the first sheet to which the second sheet is attached into a circle having an arbitrary radius centered on the equidistant position so as to encompass the first through holes.

[10] The manufacturing method according to any one of [3] to [9], wherein the shape of the first through hole and the shape of the second through hole when viewed in the thickness direction from the polishing surface side of the polishing pad are both circular.

[11] The manufacturing method according to any one of [3] to

[10] , wherein the equivalent circle diameter of the first through holes is 5 to 30 mm larger than the equivalent circle diameter of the second through holes.

[12] The manufacturing method according to any one of [3] to

[11] , further comprising a step of providing grooves (e.g., embossed grooves) on the polished surface of the first sheet.

[13] The manufacturing method according to any one of [3] to

[12] , wherein the step of arranging the window member comprises arranging the window member so that the top of the window member is higher than the bottom of the groove when the polished surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface.

[14] A method for manufacturing a polishing pad, comprising the following steps: preparing a first sheet having a polishing surface and a surface opposite to the polishing surface (opposite surface), and a second sheet having an adhesive on at least one surface of the sheet; forming a first through hole penetrating the first sheet in a thickness direction from the polishing surface to the opposite surface; bonding the first sheet and the second sheet together so that the opposite surface of the first sheet and the surface of the second sheet having the adhesive face each other; arranging a film in the first through hole of the first sheet to which the second sheet is bonded, wherein the film is a colored film and has approximately the same shape as the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and acquiring position information of the first through hole. a step of forming a second through hole penetrating the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side based on the acquired position information, wherein the second through hole is formed such that the outer periphery of the second through hole is covered by the outer periphery of the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and a step of removing the film after the second through hole is formed, and placing a window member within the first through hole and on the adhesive-bearing surface of the second sheet.

[15] The manufacturing method of

[14] , further comprising the step of preparing a cutting device including: a photographing unit that photographs the first sheet from above the polished surface of the first sheet when the polished surface of the first sheet is placed on top; a control unit that identifies the position of a first through hole from the image photographed by the photographing unit and, based on information about the identified position of the first through hole, commands the formation of a second through hole that penetrates the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polished surface side; and a hole forming unit that forms the second through hole in accordance with the command of the control unit, wherein the step of acquiring position information includes the control unit identifying the position of the first through hole from the image photographed by the photographing unit.

[16] The manufacturing method of

[15] , further comprising the step of preparing a cutting device including: a photographing unit that photographs the first sheet from above the polished surface of the first sheet when the polished surface of the first sheet is placed on top; a control unit that identifies the position of a first through hole from the image photographed by the photographing unit and, based on information about the identified position of the first through hole, commands the formation of a second through hole that penetrates the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polished surface side; and a hole forming unit that forms the second through hole in accordance with the command of the control unit, wherein the step of acquiring position information includes the control unit identifying the position of the first through hole from the image photographed by the photographing unit.

[0010] With regard to the first problem, according to the present invention, it is possible to improve the adhesion between the back surface of the window member of a polishing pad with an endpoint detection window (window member) and the adhesive surface of the second sheet. This makes it possible to manufacture a polishing pad in which the window member is less likely to peel off from the polishing pad. Furthermore, because the window member is fixed in close contact with the adhesive surface, it is possible to suppress the penetration of slurry. Furthermore, uneven wear is less likely to occur during polishing. With regard to the second problem, according to the present invention, it is possible to simply and efficiently manufacture a polishing pad with an endpoint detection window, reducing the amount of manual operation required by humans.

[0011] FIG. 1 is a schematic cross-sectional view (end view of a cut portion) in the thickness direction of a polishing pad of one embodiment obtained by the method of the present invention. FIG. 2 is a view of a polishing pad of one embodiment obtained by the method of the present invention when viewed in the thickness direction from the polishing surface. FIG. 3A is a schematic cross-sectional view (end view of a cut portion) of a polishing pad of one embodiment obtained by the method of the present invention when polishing an object to be polished with the polishing pad of one embodiment obtained by the method of the present invention. FIG. 3B is a schematic cross-sectional view (end view of a cut portion) along line A-A in FIG. 2 when polishing an object to be polished with the polishing pad of one embodiment obtained by the method of the present invention. FIG. 4 is a diagram showing an example of the placement location of a spacer used in the pressing step in the method of the present invention. FIG. 5 is a diagram of a polishing pad produced by the method of the present invention (before the pressing step). FIG. 6 is a diagram of a polishing pad produced by the method of the present invention (during pressing). FIG. 7 is a diagram explaining each step of the method of the present invention. FIG. 8 is a diagram showing the pad thickness of the entire pad in Example 1. FIG. 9 is a diagram showing the pad thickness around the first window member of the three window members in Example 1. FIG. 10 is a diagram showing the pad thickness around the second window member of the three window members in Example 1. FIG. 11 is a diagram showing the pad thickness around the third window member out of the three window members of Example 1. In FIG.

[0012] Hereinafter, an embodiment of the present invention will be described.

[0013] <<Method for Manufacturing Polishing Pad>> <First Aspect> A method for manufacturing a polishing pad according to a first aspect of the present invention is a polishing pad including a first sheet having a first through hole, a second sheet having a second through hole, and a window member, wherein the first sheet has a polishing surface for polishing an object to be polished, the second sheet is bonded to a surface of the first sheet opposite to the polishing surface, the second through hole is formed such that, when the first sheet is viewed in a thickness direction from the polishing surface side, the outer periphery of the second through hole is covered by the outer periphery of the first through hole, and the window member is disposed within the first through hole and on the second sheet such that, when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface, A method for manufacturing a polishing pad, comprising the steps of: preparing the polishing pad; and placing the polishing pad on a lower platen of a press machine having an upper platen and a lower platen, placing spacers of a predetermined thickness on the lower platen around the polishing pad, and pressing the polishing pad with the press machine, wherein the thickness S of the spacer is within the range of the thickness of the second sheet≦S≦(H−Tave1), and the pressing pressure is 0.8 MPa or less. (Here, S is the thickness of the spacer, H is the thickness of the polishing pad before pressing, and Tave1 is the average depth from the polishing surface to the upper surface of the window member before pressing.) Each step will be described below.

[0014] <1. Step of Preparing a Polishing Pad> The step of preparing a polishing pad includes preparing a polishing pad including a first sheet having a first through hole, a second sheet having a second through hole, and a window member, wherein the first sheet has a polishing surface for polishing an object to be polished, the second sheet is bonded to the surface of the first sheet opposite the polishing surface, the second through hole is formed such that, when viewed in the thickness direction from the polishing surface side of the first sheet, the outer periphery of the second through hole is covered by the outer periphery of the first through hole, and the window member is disposed within the first through hole and on the second sheet so that, when the polishing surface is the upper surface and the surface of the second sheet opposite the surface bonded to the first sheet is the lower surface, the top of the window member is lower than the polishing surface. The polishing pad is not particularly limited as long as it has the above-described configuration, and may be a commercially available polishing pad or a manufactured polishing pad. The polishing pad may also be manufactured by the method described in the second aspect. The polishing pad may be buffed or may have grooves. Each of the components will be described below.

[0015] (First Sheet) The first sheet is a sheet having an abrasive surface and a surface opposite the abrasive surface (opposite surface). The first sheet may be composed of one layer or two or more layers. However, when the first sheet is composed of two or more layers, all of the two or more layers must be pierced by the first through-holes. When the first sheet is composed of two or more layers, it is preferable that at least the layer having the abrasive surface (abrasive layer) is made of resin (resin sheet). Examples of resins include polyurethane resin, polyester resin, and polyethylene resin. Among these, polyurethane resin is more preferable in consideration of compression properties and flexibility. The first sheet may be composed of one type of resin or two or more types of resin. Note that when the first sheet is composed of multiple layers, the layer having the abrasive surface is referred to as the abrasive layer, and the other layers below the abrasive layer when viewed in the thickness direction with the abrasive surface facing upward are sometimes referred to as substrate layers. When the first sheet is composed of multiple layers, even if the layer on the polishing surface side (polishing layer) is composed of a soft resin, a certain degree of hardness can be ensured, making it easy to handle and facilitating adhesion to the second sheet. When the first sheet is composed of a polishing layer and a base layer, it is preferable that at least the polishing layer is composed of a resin. The base layer may be composed of a resin, a resin-containing nonwoven fabric, a resin-free nonwoven fabric, or a combination of two or more of these layers. Among these, the base layer is preferably composed of a resin or a resin-containing nonwoven fabric, and a flexible sheet or nonwoven fabric substrate made of polyethylene terephthalate resin (preferably a polyurethane resin-containing nonwoven fabric substrate produced by impregnating a nonwoven fabric with a polyurethane resin) is more preferable. The first sheet may be commercially available or may be manufactured. When manufacturing the first sheet, for example, a first sheet having a polishing layer and a base layer can be manufactured by wet-forming a polyurethane resin and bonding it to a flexible sheet substrate or nonwoven fabric substrate made of polyethylene terephthalate resin.The polishing layer alone may be used as the first sheet without bonding the polishing layer and the base layer together, or the polishing layer may be bonded to another sheet to form a first sheet consisting of two or more layers. Furthermore, when producing the first sheet, a first sheet having a polishing layer and a base layer may be produced by wet-forming a polyurethane resin film and bonding it to a flexible sheet made of polyethylene terephthalate resin, for example, with reference to Japanese Patent Nos. 5,421,635 and 5,844,189.

[0016] When the first sheet has a multilayer structure, the layers may be bonded and fixed together using an adhesive or the like, while applying pressure as necessary. There are no particular limitations on the adhesive used, and any adhesive known in the art may be selected and used. Alternatively, the layers may be directly bonded and fixed together by applying pressure and / or heat.

[0017] Furthermore, the first sheet preferably has open cells. Here, "open cells" refers to foaming in which adjacent cells are connected to each other by interconnecting pores. Specifically, it may be a resin formed by a wet film-forming method, or a foam formed by dry molding or injection molding. A wet film-forming method is preferred, as it is expected to be soft and have good flexural movement (compression recovery characteristics). When the first sheet is composed of two or more layers, it is preferable that at least the layer closest to the polishing surface (polishing layer) has open cells. All layers constituting the first sheet may have open cells. From the viewpoint of handleability, a configuration in which a resin layer (polishing layer) having open cells is bonded to a flexible sheet or nonwoven fabric substrate made of polyethylene terephthalate resin (preferably a polyurethane resin-containing nonwoven fabric substrate produced by impregnating a nonwoven fabric with a polyurethane resin) is preferred. In this specification, "resin formed by a wet film-forming method" refers to a resin (preferably a polyurethane resin) formed by a wet film-forming method. The wet film-forming method involves dissolving the resin to be formed into a film in an organic solvent, applying the resin solution to a sheet-like substrate, and then immersing the resin in a coagulating liquid (water) to solidify it. Wet-formed resins generally have teardrop-shaped bubbles (anisotropic structures with diameters increasing downward from the polishing surface of the polishing pad) formed by removing the organic solvent. Therefore, wet-formed resins can also be referred to as resins with teardrop-shaped bubbles. The teardrop-shaped bubbles are preferably in the form of open cells. Furthermore, the first sheet or the polishing layer constituting the first sheet is preferably composed of a wet-formed sheet (preferably a polyurethane sheet), more preferably a polyurethane sheet containing teardrop-shaped bubbles, and even more preferably a polyurethane sheet containing open cells in which some or all of the teardrop-shaped bubbles are connected by interconnecting pores. When the first sheet or polishing layer has interconnected cells with communicating holes, the interconnected cells also open on the side surfaces of the first through holes provided in the first sheet or polishing layer, and some of these cells communicate with the polishing surface or groove area.The first sheet may be transparent, translucent, or opaque, but is preferably opaque.

[0018] The first sheet has a polishing surface for polishing an object to be polished. The polishing surface refers to the surface that comes into contact with the object to be polished when the object is polished using a polishing pad. The object to be polished is not particularly limited, and examples thereof include product substrates (e.g., including multiple memory or processor dies), test substrates, bare substrates, and semiconductor substrates. The substrate can be at various stages of integrated circuit manufacturing; for example, the substrate can be a bare wafer or one or more deposited and / or patterned layers. The first sheet may also be referred to as a polishing layer. The surface opposite the polishing surface (opposite surface) is the surface of the first sheet opposite the polishing surface and that comes into contact with the second sheet.

[0019] The thickness of the first sheet or polishing pad can be determined using a Schopper-type thickness measuring instrument (pressure surface: circular with a diameter of 1 cm) in accordance with the Japanese Industrial Standards (JIS K 6505). Specifically, the method is as follows: A sample measuring 10 cm square is prepared. The sample is placed on the measuring instrument with the surface facing up. A load of 100 g / cm is applied. 2The pressure-applied surface is placed on the sample, and the thickness is measured after 5 seconds. Five points are measured per sheet, and the average value is the thickness. If a 10 cm square sample cannot be obtained, the average of the five points is used. There are no particular restrictions on the thickness of the first sheet, but it is preferably 0.5 to 3 mm, more preferably 0.6 to 2.8 mm, even more preferably 0.7 to 2.6 mm, even more preferably 0.8 to 2.5 mm, even more preferably 0.8 to 2.3 mm, and even more preferably 1.0 to 2.2 mm. There are no particular restrictions on the thickness of the polishing pad, but the thickness of the polishing pad before the pressing step is preferably 0.5 to 5 mm, more preferably 0.6 to 4 mm, even more preferably 0.7 to 3.5 mm, even more preferably 0.8 to 3.3 mm, even more preferably 1.0 to 3.0 mm, even more preferably 1.1 to 2.8 mm, even more preferably 1.2 to 2.6 mm, and even more preferably 1.2 to 2.4 mm.

[0020] (Compressibility and Compressive Modulus) In this specification, compressibility is an index of softness, and compressive modulus is an index of the ease of recovery from compressive deformation. Compressibility can be determined using a Schopper-type thickness gauge (pressure surface: circular with a diameter of 1 cm) in accordance with the Japanese Industrial Standards (JIS L 1021). Specifically, it is as follows. The thickness t0 is measured after an initial load is applied for 30 seconds from an unloaded state, and then the thickness t1 is measured after a final load is applied for 5 minutes from the thickness t0 state. Next, all loads are removed from the thickness t1 state, and the sample is left for 5 minutes (to return to an unloaded state), after which the initial load is again applied for 30 seconds and the thickness t0' is measured. The compressibility can be calculated using the formula: Compressibility (%) = 100 × (t0 - t1) / t0 (note that the initial load is 100 g / cm 2 , final load is 1120 g / cm 2 The compressive elastic modulus can be calculated using the formula: compressive elastic modulus (%) = 100 × (t0'-t1) / (t0-t1) (initial load is 100 g / cm 2 , final load is 1120 g / cm 2The compressibility of the first sheet is preferably 1 to 60%, more preferably 2 to 55%, and even more preferably 3 to 50%. The compressive modulus of the first sheet is preferably 50 to 100%, more preferably 60 to 99%, and even more preferably 85 to 99%. When the compressive modulus is within the upper range, the pad is compressed during the pressing process, and the upper platen of the press presses the window member, sufficiently adhering the window member and the adhesive layer, and then the pad can return to its original shape. Furthermore, when the compressibility and / or compressive modulus are within the above range, the polishing pad is easily pressed by the object to be polished when the object passes over the first through hole, and recovery is also excellent. Therefore, the bending and stretching movement when the first sheet is compressed and released makes it easier to suppress the adhesion of polishing debris collected on the opening wall. Furthermore, a flow of slurry is created inside the first through hole, and polishing debris collected on the outer periphery of the first through hole is easily carried by the slurry flow and discharged from the groove. This makes it easier to prevent slurry from remaining in the opening.

[0021] (Buffing) After the first sheet is manufactured, if a skin layer is present on its polishing surface, the skin layer may be buffed. Therefore, the polishing surface of the first sheet of the polishing pad may be buffed. When buffing (grinding) is performed, the polishing surface may be ground to a depth of 50 to 300 μm, preferably 80 to 250 μm, using sandpaper or the like. Buffing (grinding) removes the skin layer, allowing the polishing surface to have open pores derived from the bubbles formed during wet film formation. This improves the retention of slurry. Furthermore, if the first sheet or its polishing layer has open cells, buffing facilitates the discharge of slurry and polishing debris from the first through-holes through the communicating holes to the polishing surface.

[0022] (Grooves) The polishing pad may have grooves on the polishing surface of the first sheet. The grooves do not penetrate the first sheet in the thickness direction, and therefore can be distinguished from first through holes. Examples of grooves include embossed grooves obtained by embossing the polishing surface and cut grooves obtained by cutting with a cutting tool. Among these, embossed grooves are preferred. By providing grooves such as embossed grooves, it is possible to obtain a polishing pad that is less likely to produce burrs on the polishing surface and is suitable for finish polishing. Embossed grooves can be obtained, for example, by embossing. Figure 2 shows an embodiment in which embossed grooves 8 are formed on the polishing surface. For simplicity, grooves such as embossed grooves are not shown in Figures 4 and 7, but a configuration having grooves is also possible. The grooves may be arranged so that, with the polishing surface facing up, the top of the window member is flush with the bottom of the groove, or so that the top of the window member is higher or lower than the bottom of the groove. However, it is preferable that the top of the window member is flush with or higher than the bottom of the groove, and more preferably so that the top of the window member is higher than the bottom of the groove. Figure 1 shows an embodiment in which the top 4' of the window member 4 is arranged higher than the bottom 8' of the groove 8. With this configuration, slurry and polishing debris that flow into the surface of the window member in the first through hole flows out through the groove connected to the side of the first through hole due to centrifugal force during polishing, making it less likely that slurry and polishing debris will remain on the surface of the window member (Figures 2 and 3B). There are no particular limitations on the depth of the groove as long as it is smaller than the thickness of the first sheet, but it is preferably 50 to 90% of the thickness of the first sheet, and more preferably 60 to 80%. Furthermore, when the first sheet is composed of two or more layers, the depth of the groove is preferably equal to or less than the thickness of the polishing layer, more preferably 50 to 90% of the thickness of the polishing layer, and even more preferably 60 to 80%. If the groove disappears during the polishing process, the flow and discharge of the polishing slurry will be lost, the polishing performance will decrease, and the polishing pad will reach the end of its life, so the groove depth is preferably deep. On the other hand, in the case of embossed grooves, etc., increasing the groove depth requires increasing the processing pressure or processing temperature, which may cause deterioration of the surface of the first sheet.When the groove depth is within the above range, these problems are unlikely to occur. There are no particular restrictions on the number or shape of the grooves, and the number and shape of the grooves may be adjusted appropriately depending on the intended use of the polishing pad. Examples of shapes include lattice, radial, concentric, and honeycomb shapes, and these may be combined.

[0023] (Second Sheet) The second sheet refers to a sheet that can be bonded (adhered) to other materials (for example, the first sheet or a window member). The second sheet has a surface (second sheet surface) that contacts the surface (opposite surface) of the first sheet opposite the polishing surface. An adhesive is applied to the second sheet surface that contacts the opposite surface of the first sheet. The first sheet and the second sheet are bonded together via this adhesive. That is, the first sheet and the second sheet are bonded together so that the opposite surface of the first sheet and the second sheet surface contact each other via the adhesive. There are no particular restrictions on the second sheet as long as it has an adhesive on at least one surface. Examples of materials for the second sheet include polyolefin-based sheets such as polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymers; polyester-based sheets such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); vinyl chloride-based sheets, vinyl acetate-based sheets, polyimide-based sheets, polyamide-based sheets, fluororesin-based sheets, and resin-impregnated nonwoven fabrics, nonwoven fabrics, and woven fabrics. The second sheet is preferably a non-porous sheet that does not allow the slurry to penetrate into its interior. Among these, polyester-based sheets are more preferred for the second sheet, from the standpoints of physical properties (e.g., dimensional stability, thickness accuracy, processability, tensile strength), economy, etc., and polyethylene terephthalate (PET) sheets are particularly preferred. The adhesive is not particularly limited as long as it can bond the first sheet and the second sheet, and various adhesives can be used. Examples of adhesives include acrylic, urethane, and epoxy adhesives. Among these, acrylic adhesives are preferred because they are compatible with window materials. The adhesive-bearing surface of the second sheet may be covered with release paper or the like until it is bonded to the first sheet. The release paper can be peeled off from the surface of the second sheet when bonding the second sheet and the first sheet. This maintains the adhesive strength of the adhesive and prevents impurities such as dust and dirt from getting between the second sheet and the first sheet.As a result, the problem of peeling between the second sheet and the first sheet during polishing can be reduced. The second sheet may be commercially available or manufactured. The second sheet may be composed of one layer or two or more layers. When composed of two or more layers, the materials constituting each layer may be the same or different materials. When the second sheet has a multi-layer structure, the multiple layers may be bonded (adhered) and fixed together using an adhesive or pressure-sensitive adhesive, etc., while applying pressure as necessary. There are no particular limitations on the adhesive or pressure-sensitive adhesive used, and any adhesive or pressure-sensitive adhesive known in the art may be selected and used. Alternatively, the multiple layers may be directly bonded and fixed together by applying pressure and / or heat. When the second sheet is composed of two or more layers, the two or more layers may be bonded together directly or via an adhesive or pressure-sensitive adhesive. Furthermore, when the material constituting the second sheet is in the form of single-sided or double-sided tape, the two or more layers constituting the second sheet may be bonded together using the adhesive surface of the single-sided or double-sided tape. When the second sheet is composed of two or more layers, all of the two or more layers are penetrated by the second through holes. The second sheet may be composed of one type of material, or two or more types of materials. The second sheet may have an adhesive not only on the surface that contacts the first sheet but also on the opposite surface. In this case, it is preferable that the surface opposite to the surface that contacts the first sheet is covered with release paper or the like. This allows the release paper to be peeled off from the surface of the second sheet that constitutes the polishing pad opposite to the surface that contacts the first sheet during polishing of the workpiece, and the polishing pad can be fixed to the polishing table using the adhesive. The second sheet and the first sheet can be bonded together via the adhesive by overlapping the adhesive-bearing surface of the second sheet and the surface of the first sheet opposite to the polishing layer of the first sheet so that they face each other (contact each other). The second sheet has a lower transparency than the window member, preferably translucent or opaque, and more preferably opaque.

[0024] The thickness of the second sheet is not particularly limited, but is preferably 0.01 to 2.0 mm, more preferably 0.02 to 2.0 mm, even more preferably 0.1 to 2.0 mm, even more preferably 0.1 to 1.5 mm, even more preferably 0.1 to 1.0 mm, even more preferably 0.1 to 0.8 mm, even more preferably 0.2 to 0.6 mm, even more preferably 0.2 to 0.4 mm, and even more preferably 0.2 to 0.3 mm. The thickness of the second sheet here refers to the thickness of the second sheet when it is bonded to the first sheet. Therefore, the thickness of the second sheet does not include the thickness of the release paper that may be covering the surface of the second sheet that contacts the first sheet (before being bonded to the first sheet), and if there is release paper covering the surface opposite to the surface that contacts the first sheet, the thickness of that paper is included.

[0025] (First Through Hole) When viewed in the thickness direction from the polishing surface side of the first sheet, the first through hole is a hole that penetrates from the polishing surface of the first sheet to the opposite surface of the first sheet. The first through hole preferably penetrates the first sheet parallel to the thickness direction or perpendicular to the polishing surface. One or more (preferably two or more, more preferably three or more) first through holes may be provided in the first sheet. Furthermore, the multiple first through holes may be provided separately and independently from each other. The first sheet 2 shown in FIG. 7 has three first through holes. These three first through holes are formed on the circumference of a circle whose center is the same point as the center of the polishing pad, with the centers of the respective through holes evenly spaced apart (i.e., the center of a certain through hole and the center of another through hole adjacent to that through hole are formed on the circumference of the circle with an angle (central angle) of 120 degrees from the point). Examples of the shape of the first through hole when viewed in the thickness direction of the polishing pad from the polishing surface side of the polishing pad, the cross-sectional shape of the first through hole when cut perpendicular to the thickness direction of the polishing pad, and / or the shape of the first through hole on the polishing surface include a circle, an ellipse, a triangle, a rectangle, a hexagon, an octagon, etc. Alternatively, the first through hole may be a shape in which a plurality of the same or different shapes partially overlap each other. Among these, a circle is particularly preferred.

[0026] (Circle-equivalent diameter) In this specification and claims, the circle-equivalent diameter refers to the diameter of a perfect circle corresponding to the area of ​​the figure to be measured. The circle-equivalent diameter of the first through hole is the circle-equivalent diameter of the first through hole when viewed in the thickness direction of the polishing pad from the polishing surface side of the polishing pad. If the shape of the first through hole when viewed in the thickness direction of the polishing pad from the polishing surface side of the polishing pad is circular, it corresponds to the diameter. In the method of the present invention, the circle-equivalent diameter of the first through hole in any first sheet cross section obtained by cutting the first sheet of the polishing pad perpendicular to the thickness direction (or parallel to the polishing surface) is approximately the same as the circle-equivalent diameter of the first through hole in any other first sheet cross section obtained by cutting the first sheet perpendicular to the thickness direction. Therefore, the circle-equivalent diameter of the first through hole when viewed in the thickness direction from the polishing surface side of the first sheet may also be the circle-equivalent diameter of the first through hole in a cross section obtained by cutting the first sheet in a direction perpendicular to the thickness direction. There are no particular restrictions on the circle-equivalent diameter of the first through holes, but it is preferably 5 to 40 mm, more preferably 7 to 30 mm, and even more preferably 10 to 28 mm.

[0027] (Second Through Hole) The second through hole is a hole that penetrates from the surface of the second sheet that is in contact with the first sheet to the surface of the second sheet opposite to the surface that is in contact with the first sheet when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad. The second through hole preferably penetrates the second sheet parallel to the thickness direction or perpendicular to the polishing surface.

[0028] Examples of the shape of the second through holes when viewed in the thickness direction of the polishing pad from the polishing surface side of the polishing pad, the cross-sectional shape of the second through holes when cut perpendicular to the thickness direction of the polishing pad, and / or the shape of the second through holes on the surface of the second sheet include circles, ellipses, triangles, rectangles, hexagons, octagons, and combinations of these shapes. Alternatively, the same or different shapes may be partially overlapping each other. Among these, circles are particularly preferred because they do not form corners where polishing debris tends to accumulate, and the adhesive surfaces for attaching the window members formed between the first and second through holes are evenly spaced, preventing the window members from peeling off. In the polishing pad of the present invention, the cross-sectional shapes of the first through holes and the second through holes when cut perpendicular to the thickness direction may be the same or different, but preferably have the same shape. Among these, it is preferred that the cross-sectional shapes of the first through holes and the second through holes when cut perpendicular to the thickness direction are both circular. That is, it is preferable that the shape of the first through hole and the shape of the second through hole when viewed in the thickness direction from the polishing surface side of the polishing pad are both circular.

[0029] The second through hole is provided such that the outer periphery 5' of the first through hole covers the outer periphery 6' of the second through hole when viewed in the thickness direction from the polishing surface side of the polishing pad (see FIG. 2). More preferably, both the first through hole and the second through hole are cylindrical, and the second through hole is provided such that the cylindrical central axis of the first through hole coincides with the cylindrical central axis of the second through hole. "The outer periphery of the first through hole covers the outer periphery of the second through hole" means that the second through hole exists within the first through hole when viewed in the thickness direction from the polishing surface side. Note that, when a film described below is disposed within the first through hole, "The outer periphery of the first through hole covers the outer periphery of the second through hole" means that the second through hole exists within the first through hole when viewed in the thickness direction from the polishing surface side without the film. In the polishing pad obtained by the method of the present invention, the second through hole exists within the first through hole when viewed in the thickness direction, so that the first through hole and the second through hole are connected in the thickness direction of the polishing pad. Because the first through hole and the second through hole are connected in the thickness direction of the polishing pad, light can be transmitted from the second through hole side to the first through hole side through a window member provided in the first through hole, allowing optical detection of the surface condition of the workpiece during polishing. Furthermore, the first through hole 5 is positioned so that, when the polishing pad is viewed in the thickness direction from the polishing surface side, a portion of the second sheet 3 (hereinafter referred to as the exposed portion 7 of the second sheet) and the second through hole 6 are exposed. This allows a window member to be disposed within the first through hole and above the second through hole and exposed portion of the second sheet 3. When the first through hole of the polishing pad is viewed in the thickness direction from the polishing surface side, the second through hole and a portion of the second sheet can be seen. This portion of the second sheet is referred to as the exposed portion. Referring to FIG. 1 , in a thickness direction cross section of the polishing pad 1 of the present invention, the first through hole 5 is provided in the first sheet 2 above the second through hole 6 and exposed portion 7. The second sheet may have one second through hole, or two or more through holes spaced apart and independent from each other. It is preferable that the number of first through holes and the number of second through holes are equal.When a plurality of first through holes and a plurality of second through holes are provided, each first through hole is preferably provided on a corresponding second through hole provided in the second sheet and its exposed portion. Preferably, no window member is provided in the second through hole. Also, preferably, the second through hole is hollow (no member is provided in the second through hole).

[0030] (Circle-equivalent diameter) In this specification and claims, the circle-equivalent diameter of the second through hole refers to the circle-equivalent diameter of the second through hole when viewed in the thickness direction of the polishing pad from the polishing surface side of the polishing pad or when viewed in the thickness direction of the second sheet. If the shape of the second through hole when viewed in the thickness direction of the polishing pad from the polishing surface side of the polishing pad is circular, it corresponds to the diameter. In the polishing pad obtained by the method of the present invention, the circle-equivalent diameter of the second through hole in any second sheet cross section obtained by cutting the second sheet of the polishing pad perpendicular to the thickness direction is equal to the circle-equivalent diameter of the second through hole in any other second sheet cross section obtained by cutting the second sheet perpendicular to the thickness direction. Therefore, the circle-equivalent diameter of the second through hole may be the circle-equivalent diameter of the second through hole on the surface of the second sheet that contacts the first sheet. The circle-equivalent diameter of the second through hole is smaller than the circle-equivalent diameter of the first through hole. Conversely, the circle-equivalent diameter of the first through hole is larger than the circle-equivalent diameter of the second through hole. As long as the circle-equivalent diameter of the first through hole is larger than the circle-equivalent diameter of the second through hole, there is no particular limitation on the difference in size between the first through hole and the second through hole, but from the viewpoint of being able to sufficiently suppress clogging of the optical path by polishing debris and to prevent peeling of the window member, the circle-equivalent diameter of the first through hole is preferably 5 to 30 mm larger than the circle-equivalent diameter of the second through hole, more preferably 6 to 25 mm larger, and even more preferably 7 to 20 mm larger. Furthermore, when viewed in the thickness direction from the polishing surface side of the polishing pad, the outer periphery 5' of the first through hole is arranged so as to cover the entire outer periphery 6' of the second through hole, and the circle-equivalent diameter of the first through hole is preferably 5 to 30 mm larger than the circle-equivalent diameter of the second through hole, more preferably 6 to 25 mm larger, even more preferably 7 to 20 mm larger, even more preferably 8 to 20 mm larger, even more preferably 9 to 20 mm larger, and even more preferably 10 to 20 mm larger. Furthermore, when viewed in the thickness direction from the polishing surface side of the polishing pad, the outer periphery 5' of the first through hole is arranged to cover the entire outer periphery 6' of the second through hole, and the circle-equivalent diameter of the first through hole is preferably 1.5 to 4 times the circle-equivalent diameter of the second through hole, more preferably 2 to 4 times, and even more preferably 2.5 to 3 times.Furthermore, in the method of the present invention, when viewed from the polishing surface side of the polishing pad in the thickness direction of the polishing pad, the shortest distance between the outer periphery 6' of the second through hole and the outer periphery 5' of the first through hole (i.e., the shortest distance between any point on the outer periphery 6' of the second through hole and any point on the outer periphery 5' of the first through hole) is preferably greater than 0, more preferably 2 to 15 mm, even more preferably 3 to 12 mm, and even more preferably 4 to 10 mm. When the difference in size between the first through hole and the second through hole is within the above range, the centrifugal force during polishing causes the polishing slurry and polishing debris to move toward the outer periphery of the first through hole, making it less likely that the polishing debris will block the optical path. Therefore, excellent light transmittance can be maintained, and stable signal strength for endpoint detection can be obtained during polishing. Furthermore, because the exposed portion of the second sheet is sufficiently wide, the adhesive (adhesion) strength between the window member and the second sheet can be maintained, preventing peeling of the window member. There is no particular limitation on the equivalent circle diameter of the second through hole as long as the equivalent circle diameter of the first through hole is larger than the equivalent circle diameter of the second through hole, but the equivalent circle diameter of the second through hole is preferably 1 to 20 mm, more preferably 2 to 18 mm, and even more preferably 5 to 15 mm.

[0031] (Window Member) When viewed in the thickness direction from the polishing surface, the window member has approximately the same shape as the first through hole. Preferably, it has the same shape as the first through hole. By irradiating light onto the workpiece through the window member, it is possible to detect when the workpiece has reached the desired surface characteristics and flatness. The window member is arranged within the first through hole and on the second sheet so that the top of the window member is lower than the polishing surface when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface. The window member is arranged within the first through hole. Preferably, it is arranged within the first through hole and above the second through hole and exposed portion of the second sheet. Also, preferably, the window member is not arranged within the second through hole. Referring to FIG. 1 , when viewed in a cross section in the thickness direction, the window member 4 is arranged within the first through hole 5 and above the second through hole 6 and exposed portion 7 of the second sheet 3. The window member is adhered (sticky) to the exposed portion of the second sheet. That is, the window member is bonded to the exposed portion of the second sheet via an adhesive on at least one surface of the second sheet. Therefore, the window member is positioned on the exposed portion and within the first through hole by the adhesive on the exposed portion of the second sheet. The window member may also be bonded to the side surface of the first through hole of the first sheet, but it is preferable that the window member is not bonded to the side surface. The adhesive on the exposed portion fixes the window member on the exposed portion and within the first through hole. If the window member is bonded to the side surface of the first through hole of the first sheet, the window member cannot flexibly move toward the exposed portion 7 and adhere tightly when pressed during the pressing process. Furthermore, after pressing, a force acts on the first sheet to return to its pre-press state, making the window member more likely to separate from the exposed portion 7. On the other hand, because the window member is not bonded to the side surface of the first through hole of the first sheet, the pressing process can more firmly bond the window member 4 to the exposed portion 7.

[0032] The window member is preferably made of resin. The resin constituting the window member is not particularly limited as long as it is transparent enough to transmit light. However, it is preferable to use a material with a light transmittance of 20% or more over the entire wavelength range of 300 to 700 nm, and more preferably a material with a light transmittance of 50% or more. Examples of such materials include thermosetting resins such as polyurethane resin, polyester resin, phenolic resin, urea resin, melamine resin, epoxy resin, and acrylic resin; thermoplastic resins such as polyurethane resin, polyester resin, polyamide resin, cellulose-based resin, acrylic resin, polycarbonate resin, halogen-based resins (such as polyvinyl chloride, polytetrafluoroethylene, and polyvinylidene fluoride); polystyrene resin; and olefin-based resins (such as polyethylene and polypropylene); rubbers such as butadiene rubber and isoprene rubber; photocurable resins that are cured by light such as ultraviolet light or electron beams; and photosensitive resins. Among these, polyurethane resin, polyester resin, acrylic resin, and polystyrene resin are preferred because they have appropriate firmness at a thickness of 0.1 to 0.5 mm, excellent thickness precision, and good compatibility with adhesives. Furthermore, the uppermost surface of the window member is preferably subjected to a roughening treatment or a hydrophilic treatment so as not to repel the slurry. The window member to be used may be a commercially available product or a manufactured product.Commercially available window materials include "Diafoil T910E" and "Diafoil T600E" manufactured by Mitsubishi Chemical Corporation, which are made of polyester resin; "Cosmoshine A4300," "Cosmoshine A2330," "Cosmoshine TA017," "Cosmoshine TA015," "Cosmoshine TA042," "Cosmoshine TA044," "Cosmoshine TA048," and "Soft Shine TA009" manufactured by Toyobo Co., Ltd.; and "Acryplene HBS006," "Acryplene HBXN47," and "Acryplene HBXN47" manufactured by Mitsubishi Chemical Corporation, which are made of polymethyl methacrylate resin. "Kriplen HBS010", Teijin Chemical Co., Ltd. "Panlite Film PC-2151", Kaneka Corporation "Sunduren SD009", "Sunduren SD010", Sumitomo Chemical Co., Ltd. "C000" made of polycarbonate resin, Teijin Chemical Co., Ltd. "Iupilon H-3000", Sumitomo Chemical Co., Ltd. "C001" made of acrylic resin / polycarbonate resin), Zeon Corporation "Zeonor ZF14" and "Zeonor ZF16" made of alicyclic polyolefin resin, JSR Corporation "Arton Film", etc. can be obtained as commercially available products.

[0033] (Circle-equivalent Diameter) When viewed in the thickness direction from the polished surface, the window member has substantially the same shape as the first through hole, and preferably has the same shape as the first through hole. The circle-equivalent diameter of the window member is preferably equal to or smaller than the circle-equivalent diameter of the first through hole, more preferably within the range of "0.8 times the circle-equivalent diameter of the first through hole" to "the circle-equivalent diameter of the first through hole," even more preferably within the range of "0.9 times the circle-equivalent diameter of the first through hole" to "the circle-equivalent diameter of the first through hole," and even more preferably within the range of "0.95 times the circle-equivalent diameter of the first through hole" to "the circle-equivalent diameter of the first through hole," and may be equal to the circle-equivalent diameter of the first through hole. The circle-equivalent diameter of the window member is preferably larger than the circle-equivalent diameter of the second through hole. The window member preferably does not have communicating holes. The window member preferably does not have open cells. The window member preferably does not have open holes. This improves light transmittance.

[0034] (Upper Position of Window Member) In the method of the present invention, when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded (adhered) to the first sheet is the lower surface, the window member is preferably positioned so that the uppermost portion 4' of the window member 4 is higher than the lowermost portion 8' of the groove 8 ( FIGS. 1 and 3A ). That is, it is more preferable that the position of the window member closest to the polishing surface is higher than the deepest position (the position farthest from the polishing surface) of the groove provided in the first sheet. This makes it easier for polishing debris that has migrated to the outer periphery of the first through hole to flow into the groove together with the slurry. Furthermore, the first through hole may or may not be connected to the groove, but it is preferably connected ( FIGS. 2 and 3B ). FIG. 3B shows the end surface of the polishing pad of FIG. 2 cut along line A-A. Polishing debris 10 generated during polishing of the workpiece may collect on the outer periphery of the first through hole due to centrifugal force 11 and then flow into the groove 8 connected to the first through hole. As a result, the abrasive debris can be more easily discharged from the first through hole, which can prevent the abrasive debris from clumping together and forming abrasive debris agglomerates, making it easier to suppress the occurrence of scratches caused by abrasive debris agglomerates.

[0035] The step of preparing the polishing pad preferably includes the following steps: a step of preparing a first sheet having a polishing surface and a surface opposite to the polishing surface (opposite surface), and a second sheet having an adhesive on at least one surface of the sheet; a step of forming a first through hole penetrating the thickness direction from the polishing surface of the first sheet to the opposite surface of the first sheet; a step of bonding the first sheet and the second sheet together so that the opposite surface of the first sheet and the surface of the second sheet having the adhesive face each other; a step of placing a film in the first through hole of the first sheet to which the second sheet is bonded, wherein the film is a colored film and has approximately the same shape as the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and a step of acquiring position information of the first through hole. The method preferably includes the steps of: forming a second through hole penetrating the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side based on the acquired position information, wherein the second through hole is formed such that the outer periphery of the second through hole is covered by the outer periphery of the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and removing the film after the second through hole is formed, and placing a window member within the first through hole and on the adhesive-bearing surface of the second sheet. Each step will be described below.

[0036] <1-1. Step of Preparing a First Sheet and a Second Sheet> The method of the present invention includes a step of preparing a first sheet having a polishing surface and a surface opposite the polishing surface (opposite surface), and a second sheet having an adhesive on at least one surface of the sheet. Hereinafter, examples of the first sheet and the second sheet include those described above. (Buffing) If a skin layer is present on the polishing surface of the first sheet, the step of buffing the skin layer may be included. When buffing (grinding) is performed, the polishing surface may be ground to a depth of 50 to 300 μm, preferably 80 to 250 μm, using sandpaper or the like. Buffing (grinding) removes the skin layer, allowing the polishing surface to have openings resulting from bubbles formed during wet film formation. This improves slurry retention. The buffing may be performed after the production of the first sheet, before or after the formation of the first through-holes, or before or after bonding the first sheet and the second sheet together. However, it is preferably performed before the film placement step, more preferably before the first sheet and the second sheet are bonded together, and even more preferably before the first through-hole formation step. The first sheet may also be sliced ​​to a desired thickness. (Groove Formation) The method of the present invention may include a step of providing grooves on the polished surface of the first sheet. When the first sheet has a multi-layer structure, grooves may be provided on the surface of the layer having the polished surface after the multi-layer structure. The groove formation step may be performed before or after the formation of the first through-holes, or before or after bonding the first sheet and the second sheet together. However, it is preferably performed before the film placement step, more preferably before the first sheet and the second sheet are bonded together, and even more preferably before the first through-hole formation step. It is also preferable to perform the groove formation after the buffing step.

[0037] <1-2. Step of forming first through holes> The method of the present invention includes a step of forming first through holes 5 penetrating the first sheet 2 in the thickness direction from the polished surface (FIG. 7(a)). Note that although grooves are omitted in FIG. 7, grooves may be formed in the polished surface. The grooves can be provided as described above. Examples of the first through holes include those described above.

[0038] There are no particular limitations on the means for forming the first through holes, and examples thereof include a cutting device or a hole forming unit (hole forming device) described below. Other examples include a punching machine, a water jet device, a laser processing machine, and an ultrasonic cutter. Also, devices such as those described in JP-A-2022-149504 can be used. Furthermore, holes may be made in the thickness direction of the first sheet using a circular, elliptical, or other cutting die (preferably a circular cutting die). Among these, a cutting device is particularly preferred.

[0039] Furthermore, the step of forming the first through holes preferably includes forming first through holes at positions on the first sheet corresponding to the positions of one or more points or small circles in graphic data, the positions being determined based on graphic data in which one or more points or small circles are arranged at equal intervals on the circumference of a circle. Here, a small circle refers to a circle with a smaller radius or diameter than the circle. More specifically, when using a cutting device described below, the graphic data is input to a control unit (e.g., a computer). Based on the graphic data information input to the control unit, a hole forming unit of the cutting device determines positions on the first sheet corresponding to the positions of the points or small circles in the graphic data. For example, when the first sheet has a quadrangular shape, such as a rectangle or a square, when viewed in the thickness direction, the determination of the positions on the first sheet corresponding to the positions of the points or small circles may be performed by inputting information about the shape (size) of the sheet and information about the positions of the points or small circles to be arranged on the sheet to the control unit, and the control unit may determine the positions on the first sheet corresponding to the positions of the points or small circles based on the input information. The hole forming unit forms a first through hole by drilling a hole at a position on the first sheet that corresponds to a point or a small circle based on the determined position, for the sheet placed at a predetermined position in the cutting device. In the case of a small circle, the first through hole can be formed so that the position on the first sheet that corresponds to the circumferential portion of the small circle is the outer periphery of the first through hole, and in the case of a point, the first through hole can be formed with a predetermined radius or diameter centered on the position on the first sheet that corresponds to the point.

[0040] <1-3. Step of Bonding the Second Sheet> The method of the present invention includes a step of bonding the first sheet and the second sheet together so that the surface of the first sheet 2 opposite the polished surface (opposite surface) faces the surface of the second sheet 3 bearing the adhesive (FIG. 7(b)). The first sheet and the second sheet can be bonded together by utilizing the adhesive strength of the adhesive of the second sheet. By bonding the first sheet and the second sheet together, the adhesive surface of the second sheet is exposed within the first through-holes when viewed in the thickness direction from the polished surface. This exposed adhesive surface is sometimes referred to as the exposed surface.

[0041] <1-4. Step of placing a film in the first through hole> The method of the present invention includes a step of placing a film 12 in the first through hole 5 of the first sheet 2 to which the second sheet has been attached (FIG. 7(c)). Here, the film has approximately the same shape as the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side. The film is preferably placed in the first through hole and on the adhesive surface (exposed surface) of the second sheet.

[0042] (Film) When the first sheet is viewed in the thickness direction from the polishing surface side, the film has substantially the same shape as the first through hole, and preferably the same shape. Furthermore, the film is preferably the circle-equivalent diameter of the first through hole or less, and is preferably within the range of "0.8 times the circle-equivalent diameter of the first through hole" to "the circle-equivalent diameter of the first through hole," more preferably within the range of "0.9 times the circle-equivalent diameter of the first through hole" to "the circle-equivalent diameter of the first through hole," and even more preferably within the range of "0.95 times the circle-equivalent diameter of the first through hole" to "the circle-equivalent diameter of the first through hole," and may be equal to the circle-equivalent diameter of the first through hole.

[0043] The material of the film is not particularly limited, and examples thereof include polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyethylene terephthalate, polyethylene naphthalate, polyethylene-coated paper, and polypropylene-coated paper. The film preferably has a surface that contacts the exposed surface of the second sheet that is treated (non-adhesive) to prevent adhesion to the second sheet and facilitate easy release from the second sheet. Examples of non-adhesive treatments include surface coating with silicone or fluororesin, and surface roughening. Commercially available films may also be used. Examples of commercially available films include release paper, release liner, and separator. The thickness of the film is not particularly limited, but when placed in the first through-hole, it is preferable that the top surface of the film be at or lower than the polished surface of the first sheet, and more preferably lower than the polished surface. Examples of the film thickness include a film with a thickness of 70 to 100 μm.

[0044] There is no particular limitation on the means for placing the film in the first through-hole, and the film can be placed in the first through-hole manually using an appropriate tool such as tweezers, or by automated or robotic means.

[0045] (Color) The film is a film having a color. A colored film is a concept that does not include a film that is not colored, i.e., a colorless and transparent film. A colored film may be an opaque film or a translucent film having a color (e.g., white translucent, yellow translucent, black translucent, etc.). The film is preferably opaque. The entire surface of the film facing the polishing surface is preferably colored. The film may have a color on the surface opposite the polishing surface, or the entire surface opposite the polishing surface may have a color. The film is preferably a film having a color different from the color of the polishing surface of the first sheet, and more preferably, at least the entire surface of the film facing the polishing surface is a color different from the color of the polishing surface of the first sheet. The entire surface of the film facing the polishing surface and the other opposite surface may have a color different from the color of the polishing surface of the first sheet. The color of the surface of the film facing the polishing surface may be different from the color of the polishing surface of the first sheet to the extent that the film area and the first sheet can be distinguished. Preferably, the color of the polishing surface of the film differs in brightness (shade) from the color of the polishing surface of the first sheet to the extent that the film region and the first sheet can be distinguished. Alternatively, the two may have different saturations or hues. Among these, different brightness (shade) is preferable. For example, if the polishing surface of the first sheet is black, the entire surface of the film facing the polishing surface may be a high-brightness color such as white, yellow, light blue, or a pastel color. Furthermore, if the polishing surface is white, the entire surface of the film facing the polishing surface may be a low-brightness color such as black, navy blue, gray, or a dark color. For example, if the polishing surface of the first sheet is orange, the entire surface of the film facing the polishing surface may be blue, green, purple, or the like. Furthermore, if the polishing surface is light blue, the entire surface of the film facing the polishing surface may be red, yellow, green, or the like. As an example of a case where the saturation is different, for example, if the polished surface of the first sheet is a pure color, the entire surface of the film on the polished side may be a color close to white, black, or gray.Furthermore, when the polished surface is a color close to white, black, or gray, the entire surface of the film on the polished side may be a vivid color such as red, blue, or yellow, which has good color development.

[0046] Among these, it is preferable that the color of at least the entire surface of the film on the polished side differs in brightness (shade) from the color of the polished surface of the first sheet. The difference in brightness (shade) is not particularly limited as long as it is discernible by a camera. For example, when brightness is expressed numerically using the Munsell color system, the difference in brightness between the color of the surface of the film on the polished side and the color of the polished surface of the first sheet may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more. A larger difference in brightness is preferable. By having the entire surface of the film on the polished side have a different color from the polished surface of the first sheet, the control unit can capture image data of the first sheet captured by a photographing unit (camera) provided in the cutting device and identify the position of the film. Since the position of the film overlaps the position of the first through-hole, position information of the first through-hole can be obtained by identifying the position of the film. This allows the position of the second through hole to be formed later to be easily determined, making it easier to form the second through hole. Furthermore, using this position information, the center of the circle when cutting the first sheet to which the second sheet is attached into a circular shape can be easily identified. Furthermore, by placing a film inside the first through hole of the first sheet, it is possible to prevent dust and dirt from adhering to the adhesive surface of the second sheet exposed inside the first through hole. This increases the adhesion (tackiness) between the window member and the adhesive surface of the first sheet when the window member is placed inside the first through hole in a subsequent process, reducing the risk of the window member peeling off during polishing.

[0047] <1-5. Step of Acquiring Positional Information of the First Through Hole> The method of the present invention includes a step of acquiring positional information of the first through hole. The step of acquiring positional information of the first through hole includes identifying the position of the first through hole. The position of the first through hole may be identified by detecting the color of the film, by detecting the boundary line between the first sheet and the film, or by utilizing the color difference between the film and the polished surface. Among these, it is preferable to identify the position of the first through hole by utilizing the color difference between the film and the polished surface. Examples of means for acquiring positional information of the first through hole include a means for detecting the color of the film to acquire positional information of the first through hole, a means for detecting the outline of the first through hole to acquire positional information of the first through hole, a means for acquiring positional information of the first through hole by utilizing the color difference between the film and the polished surface, and a combination of these means. Among these, a means for acquiring positional information of the first through hole by utilizing the color difference between the film and the polished surface is preferable. As a means for detecting the color of the film to obtain position information of the first through hole, for example, if the film is blue, the position information of the first through hole can be identified by detecting the blue color on the first sheet. As a means for detecting the contour of the first through hole to obtain position information of the first through hole, for example, the contour can be obtained by detecting a location where the brightness value changes significantly from image data of the film placed in the first through hole. The contour shape can be obtained by detecting a boundary where the contrast between light and dark changes from the image data, converting it into a projected waveform, and performing a differential process to calculate the peak point of the differential waveform as the contour point. This can be extracted using image processing such as the gradient method, Sobel method, Laplacian method, and Canny method. Even if the color and brightness of the film placed in the first through hole are the same as the color and brightness of the first sheet, the boundary can be detected by unevenness if the position in the thickness direction of the film is lower or higher than the polished surface. Furthermore, even if the film in the first through hole is flush with the polished surface, the boundary can be detected by detecting the difference in brightness due to the gap between the first through hole and the film. Furthermore, the boundary of the first through hole can also be detected by increasing the difference in brightness between the film and the polished surface.Examples of means for obtaining position information of the first through hole by utilizing the difference in color between the film and the polished surface include means for binarizing and separating the film and the polished surface, such as a method of converting the RGB values ​​of each pixel in the captured image into lightness or luminance and then binarizing, a method of binarizing each of the three primary color components of the RGB values, or a method of defining an RGB color space and binarizing based on the distance of each pixel in the color space, and means for detecting the contours of the film image and distinguishing between the film and the polished surface based on the amount of color change between adjacent pixels, such as a method of converting the RGB values ​​of each pixel into lightness or luminance and then determining the amount of color change between adjacent pixels, or a method of determining the amount of color change between adjacent pixels for each of the three primary color components of RGB. The step of acquiring the position information preferably includes the photographing unit of the cutting device, which includes a photographing unit, a control unit, and a hole forming unit, photographing the first sheet on which the film is placed, and the control unit identifying the position of the film based on the image (image data) of the first sheet photographed by the photographing unit. More preferably, the control unit identifies the position of the film by identifying the color difference between the film and the polished surface in the image of the first sheet photographed by the photographing unit. Since the position of the film coincides with the position of the first through hole, identifying the position of the film allows the position of the first through hole to be identified. This allows the position information of the first through hole to be acquired. Alternatively, the control unit can also acquire the position information of the first through hole by detecting the boundary between the first through hole and the first sheet based on the image (image data) of the first sheet photographed by the photographing unit.

[0048] (Cutting Apparatus) The method of the present invention preferably further includes a step of preparing a cutting apparatus including: a photographing unit that photographs the first sheet from above the polished surface of the first sheet, with the polished surface of the first sheet facing up; a control unit that identifies the position of a first through hole from the image photographed by the photographing unit and, based on the information on the identified position of the first through hole, commands a hole forming unit to form a second through hole penetrating the second sheet within the first through hole as viewed in the thickness direction from the polished surface side of the first sheet; and a hole forming unit that forms the second through hole in accordance with the command of the control unit. Furthermore, the step of acquiring position information preferably includes the control unit identifying the position of the first through hole from the image photographed by the photographing unit. Examples of means for acquiring position information of the first through hole (or methods for identifying the position of the first through hole) include those described above. In particular, the step of acquiring position information preferably includes the control unit identifying the position of the film by identifying a color difference between the film and the polished surface in the image photographed by the photographing unit. The cutting device preferably has a stage in addition to the photographing unit, the control unit, and the hole forming unit, and more preferably further includes an X-axis driving means and a Y-axis driving means.

[0049] (Photographing Unit) When the polished surface of the first sheet is positioned on top, the photographing unit photographs the first sheet from above the polished surface of the first sheet. Preferably, the photographing unit is composed of a camera that photographs the first sheet on the stage from above, and is fixed in a position where it can photograph the entire shape of the first sheet. For example, the photographing unit may be disposed above the stage on which the first sheet is mounted. The photographing unit is linked to the control unit, and image data photographed by the photographing unit is sent to the control unit.

[0050] (Controller) Image data captured by the photographing unit is sent to the controller. The photographing unit and the controller may be connected by wire or wirelessly so that they can transmit and receive signals to each other or so that the controller can receive signals sent by the photographing unit. The controller preferably includes a display device such as a CRT or LCD and an input device such as a keyboard or mouse. The controller can instruct the photographing unit to photograph the first sheet (or polishing pad), and the photographing unit can execute the instruction. The controller identifies the position of the first through hole from the image of the first sheet photographed by the photographing unit. Furthermore, based on the information on the identified position of the first through hole, the controller instructs the hole forming unit to form a second through hole penetrating the second sheet within the first through hole when viewed in the thickness direction from the polishing surface side of the first sheet. The controller may have a dedicated processing device or may be a personal computer running CAD software. Alternatively, it may be a general-purpose computer operating as part of a CAD system. The position of the film within the surface of the first sheet is identified by processing the image data in the controller. The image data processing method may be the method described above for the means for acquiring the position information of the first through hole. Based on the information on the identified position of the first through hole, the control unit commands the hole forming unit to form a second through hole penetrating the second sheet within the first through hole when viewed in the thickness direction from the polishing surface side of the first sheet, and this command or a signal including this command is sent to the hole forming unit. The control unit and the hole forming unit may be connected by wire or wirelessly so that they can send and receive signals to each other or so that the hole forming unit can receive signals sent by the control unit.

[0051] (Hole Forming Unit) The hole forming unit (or hole forming device) forms second through holes that penetrate the second sheet in the thickness direction according to commands from the control unit. The hole forming unit has a means (through hole forming means) for forming through holes in the film and / or the second sheet. Examples of the through hole forming means include a cutter and a drill. Among these, a drill is preferred. Through holes can be formed in the film and / or the second sheet using a cutter or drill. The size of the drill is preferably the same diameter as the diameter of the second through hole. Note that the hole forming unit can also form not only second through holes but also first through holes using the through hole forming means. Furthermore, when the through hole forming means is a cutter, the first sheet bonded to the second sheet may be cut in the thickness direction using the cutter according to the size of the desired polishing pad (to obtain the desired polishing pad size). Alternatively, the hole forming unit may have a cutting means in addition to the through-hole forming means, and the cutting means may cut the first sheet bonded to the second sheet in the thickness direction according to the desired polishing pad size (to obtain the desired polishing pad size). When the through-hole forming means also forms the first through holes, information regarding the desired size, number, and / or arrangement of the first through holes (e.g., arranging three, four, five, or six through holes so that they are evenly spaced around the circumference of a circle centered on a certain point (i.e., the centers of the multiple through holes are evenly spaced around the circumference)) is input to the control unit, and then this information is sent to the hole forming unit. Based on this information, the through-hole forming means forms the first through holes. When cutting the first sheet bonded to the second sheet according to the desired polishing pad size, the control unit also calculates the position of the center of the polishing pad from the position information of the first through holes, and information regarding the calculated center position and the desired polishing pad size (e.g., radius, etc.) is sent to the hole forming unit. The through-hole forming means cuts the first sheet bonded to the second sheet to a predetermined size (for example, a predetermined radius from the center position) based on the calculated center position (forming the outer periphery of the polishing pad). A cutter blade is preferable as the cutting means. The blade formed at the lower end of the cutter blade enables cutting of the first sheet.

[0052] (Stage) The cutting device preferably has a stage. The stage includes a flat support plate on which the first sheet (or polishing pad) is placed. Preferably, the stage is configured to include a decompression chamber provided on the underside of the support plate, and a vacuum blower that evacuates air from the decompression chamber to set it to a negative pressure. In this case, the support plate is formed with a large number of fine suction holes that penetrate in the vertical direction from the upper surface of the support plate (the surface on which the first sheet is mounted) to the decompression chamber below the support plate, and the first sheet is vacuum-sucked to the support plate and fixedly held therein by setting the decompression chamber to a negative pressure with the vacuum blower.

[0053] (X-Axis Drive Means / Y-Axis Drive Means) The X-axis drive means and the Y-axis drive means are means for moving the hole forming unit in the X-axis direction (front-rear direction) and the Y-axis direction (left-right direction), respectively. The X-axis drive means and the Y-axis drive means preferably include a pair of left and right guide rails and a guide bar. The pair of left and right guide rails (two guide rails) are fixed and extend parallel to each other in the front-rear direction, sandwiching the stage. The guide bar is a single bar, preferably a rectangular cylindrical bar, arranged on the pair of guide rails and is arranged so as to be freely movable on the pair of guide rails in the direction of extension of the guide rails (X-axis direction). The hole forming unit is attached to the guide bar and is movable in the left-right direction (Y-axis direction) along the guide bar. In other words, the guide bar moves in the X-axis direction along the guide rails, and the hole forming unit on the guide bar moves in the Y-axis direction, thereby forming a through hole and / or cutting the outer periphery of the pad at the desired position. The hole forming unit is preferably supported on the guide rails so as to be freely movable in the left-right direction and is configured with a cutter holder. Preferably, the cutter holder is provided with a cutter blade and / or a drill, and the drill can form the first through-hole and the second through-hole. The first sheet can be cut by a blade formed at the lower end of the cutter blade. The cutter blade can also form the first through-hole and the second through-hole.

[0054] <1-6. Step of forming second through holes> The method of the present invention includes a step of forming second through holes 6 that penetrate the second sheet 3 within the first through holes 5 when the first sheet 2 is viewed in the thickness direction from the polishing surface side, based on the acquired position information ( FIG. 7(d) ). Here, the second through holes are formed such that the outer periphery of the second through holes is covered by the outer periphery of the first through holes when the first sheet is viewed in the thickness direction from the polishing surface side. Examples of second through holes include those described above. The step of forming the second through holes preferably includes, based on the acquired position information, forming second through holes that penetrate the second sheet within the first through holes when the first sheet is viewed in the thickness direction from the polishing surface side, by the hole forming unit.

[0055] Furthermore, the process of forming the second through hole preferably includes forming the second through hole based on the position information of the first through hole so that the center of the first through hole and the center of the second through hole are approximately identical when viewing the first sheet in the thickness direction from the polishing surface side, and more preferably includes forming the second through hole so that they are identical.

[0056] The second through holes are preferably formed automatically using a cutting device. Furthermore, a method for forming the second through holes so that the centers of the first and second through holes are substantially the same may involve, for example, determining the center position of the first through hole by calculating a center position that is equidistant from the outer periphery of the first through hole or from multiple points on the outer periphery based on the position information of the first through hole, and then forming the second through holes so that the center of the second through hole coincides with the center of the first through hole. In this case, the second through holes are formed in the thickness direction from the polished surface side, so that the film within the first through holes is also pierced by the formation of the second through holes.

[0057] <1-7. Cutting Step> The method of the present invention may further include a step of acquiring, based on the position information of the first through holes, information on positions (equidistant positions) that are equidistant from the centers of all of the first through holes when the first sheet is viewed in the thickness direction from the polishing surface side, and a step of cutting the first sheet bonded to the second sheet into a circular shape with an arbitrary radius centered on the equidistant positions and encompassing the first through holes, based on the information on the equidistant positions. This forms the outer edge of the polishing pad. The cutting step may be performed before forming the second through holes, simultaneously with forming the second through holes, after forming the second through holes, or after forming the second through holes and before placing the window member. In this step, if the position information of the first through holes includes information on the center positions of each of the multiple first through holes when the first sheet is viewed in the thickness direction from the polishing surface side, the center positions of each first through hole may be determined based on the position information. Alternatively, if the position information of the first through holes is information about the region of the first through holes or the outer periphery of the first through holes when the first sheet is viewed in the thickness direction from the polishing surface side, the centers of the first through holes may be calculated from the information about the region or outer periphery. A position (equidistant position) that is equidistant from the center of all the first through holes can be determined, and the first sheet to which the second sheet is bonded can be cut into a circle with this equidistant position as the center. Furthermore, the cutting step preferably involves cutting the first sheet to which the second sheet is bonded into a circle so that the first through holes are included in the circle to be cut. In the case where there is one first through hole, for example, a dummy pad having a through hole of the same shape and size as the first through hole on a flat surface such as paper or a resin plate, and multiple pseudo first through holes on the same circumference (for example, a dummy pad having three pseudo first through holes of the same shape and size as the first through hole arranged on the same circumference at 120-degree angles from each other), is prepared, and one through hole on the dummy pad is aligned with the position of the first through hole on the first sheet, and the one first through hole and the two pseudo first through holes are recognized as three first through holes, thereby determining a position (equidistant position) that is equidistant from the center of all the first through holes, and the first sheet to which the second sheet is attached can be cut into a circle with this equidistant position as the center.At this time, by making the brightness or luminance of the surface of the dummy pad different from the brightness or luminance of the through holes and pseudo through holes, the control unit can detect the through holes and pseudo through holes and their contours.

[0058] <1-8. Step of placing window member> The method of the present invention includes the step of removing film 12 after forming the second through hole, and placing window member 4 inside first through hole 5 and on the adhesive-bearing surface of second sheet 3 (FIG. 7(e)). Through this step, a polishing pad can be obtained. Examples of window members include those described above.

[0059] (Film Removal) There are no particular limitations on the means for removing the film, and examples thereof include a means for manually removing the film using tweezers or the like, a means for automatically removing the film using a robot arm, etc. As described above, since the film surface is subjected to a non-adhesive treatment, the film that is in the first through-hole and on the second sheet can be easily removed from the second sheet.

[0060] (Positioning of Window Member) The window member is placed within the first through hole and on the adhesive-bearing surface of the second sheet. The process of placing the window member preferably includes placing the window member within the first through hole and on the adhesive-bearing surface of the second sheet such that, when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface, the top of the window member is lower than the polishing surface. Having the top of the window member lower than the polishing surface prevents scratches on the surface of the workpiece being polished due to the window member. The process of placing the window member preferably includes placing the window member such that, when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface, the top of the window member is higher than the bottom of the groove. Having the top of the window member higher than the bottom of the groove allows polishing debris on the window member to be discharged into the groove, maintaining light transmittance.

[0061] <2. Pressing Step> The method of the present invention may further include the steps of placing the polishing pad obtained after the step of placing the window member on the lower platen 16 of a press machine having an upper platen 17 and a lower platen 16, placing spacers 15 of a predetermined thickness on the lower platen 16 and around the polishing pad 1, and pressing the polishing pad with the press (pressing force 18) (FIGS. 4, 5, and 6). At this time, the upper platen 17 of the press machine presses the polishing pad to the position of the spacers by pressing force 18. As illustrated in FIG. 4, the polishing pad is placed on the lower platen of the press machine, and the upper platen presses the polishing pad to the position of the spacers. As a result, the polishing pad before pressing shown in FIG. 5 is compressed in the thickness direction like the polishing pad during pressing shown in FIG. 6. There are no particular limitations on the sizes of the lower platen and upper platen of the press machine, as long as the entire polishing pad can be pressed. When placed on the lower platen of the press machine, the polishing pad is preferably placed so that it does not protrude from the lower platen of the press machine. The upper platen of the press is preferably positioned so that the polishing pad does not protrude from the upper platen of the press during pressing.

[0062] The thickness S of the spacer used during pressing is in the range of the thickness of the second sheet ≦ S ≦ (H-Tave1). If the spacer thickness S is less than the thickness of the second sheet, the compression amount will be too large, increasing the risk of the adhesive of the second sheet overflowing into the window member and impairing light transmittance. Furthermore, there is a risk that the pad will be crushed, resulting in the desired foam shape and therefore inability to obtain polishing performance (problems such as scratches may occur). Furthermore, even after being released from compression after pressing, the polishing pad (first sheet) may not fully recover in thickness, resulting in a reduced depth from the polishing surface to the upper window surface and a shortened product life of the pad. If the spacer thickness S exceeds H-Tave1, the upper platen of the press machine will have difficulty contacting the surface of the window member, preventing air from escaping between the window portion and the adhesive surface, leading to poor adhesion between the window portion and the adhesive surface, which may cause slurry penetration and result in peeling of the window member. In contrast, when the spacer thickness S is within the above range, the adhesive is less likely to overflow or the pad is less likely to be crushed. Furthermore, while the average depth from the polishing surface to the upper surface of the window member remains unchanged before and after pressing, the difference between the maximum and minimum depths from the polishing surface to the upper surface of the window member is sufficiently small, which has the advantage of reducing in-plane variations in the contact surface with the workpiece from the initial stage of polishing, and reducing uneven wear. Furthermore, in the pressing process, it is preferable to press the polishing pad with a press machine so that |Tave1-Tave2| (where || represents the absolute value) is ≦40 μm. |Tave1-Tave2| is more preferably ≦30 μm, even more preferably ≦25 μm, even more preferably ≦20 μm, and even more preferably ≦18 μm. Here, S is the thickness of the spacer, H is the thickness of the polishing pad before pressing, Tave1 is the average depth from the polishing surface to the upper surface of the window member before pressing, and Tave2 is the average depth from the polishing surface to the upper surface of the window member after pressing (the polishing pad after being released from pressure). For example, in the case of a polishing pad having three window members, H, Tave1, and Tave2 can be determined as follows: H: The thickness of the polishing pad was measured using a Schopper-type thickness meter (pressure surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standards (JIS K 6505), and this was taken as H.Tave1: For each of three window members before pressing, the depth from the polishing surface to the upper surface of the window member was measured using a depth gauge at four locations on the outer periphery of the upper surface of the window member and one location in the center, and the arithmetic mean of the 15 depth measurements was calculated and defined as Tave1. Tave2: For each of three window members after pressing, the depth from the polishing surface to the upper surface of the window member was measured using a depth gauge at four locations on the outer periphery of the upper surface of the window member and one location in the center, and the arithmetic mean of the 15 depth measurements was calculated and defined as Tave2. For the polishing pad after pressing, Tmax2 - Tmin2 is preferably 18 μm or less, more preferably 15 μm or less, even more preferably 13 μm or less, even more preferably 10 μm or less, even more preferably 8 μm or less, and even more preferably 6 μm or less. In the pressing process, (Tmax2 - Tmin2) / (Tmax1 - Tmin1) before and after pressing is preferably 0.5 or less, more preferably 0.45 or less, even more preferably 0.4 or less, even more preferably 0.3 or less, and even more preferably 0.2 or less. Here, Tmax1 is the maximum depth from the polishing surface to the upper surface of the window member before pressing, Tmin1 is the minimum depth from the polishing surface to the upper surface of the window member before pressing, Tmax2 is the maximum depth from the polishing surface to the upper surface of the window member after pressing, and Tmin2 is the minimum depth from the polishing surface to the upper surface of the window member after pressing. For example, in the case of a polishing pad having three window members, Tmax1, Tmin1, Tmax2, and Tmin2 can be calculated as follows. Tmax1: The largest value of the depth from the polishing surface to the upper surface of the window member at 15 locations when calculating Tave1 was taken as Tmax1. Tmin1: The smallest value of the depth from the polished surface to the upper surface of the window member at 15 locations when calculating Tave1 was taken as Tmin1. Tmax2: The largest value of the depth from the polished surface to the upper surface of the window member at 15 locations when calculating Tave2 was taken as Tmax2. Tmin2: The smallest value of the depth from the polished surface to the upper surface of the window member at 15 locations when calculating Tave2 was taken as Tmin2.

[0063] The pressing pressure applied by the press is 0.8 MPa or less, preferably 0.1 to 0.6 MPa, more preferably 0.1 to 0.5 MPa, even more preferably 0.1 to 0.4 MPa, even more preferably 0.2 to 0.4 MPa, and most preferably 0.3 MPa. The pressing time by the press is 10 seconds or less, preferably 3 to 7 seconds, more preferably 4 to 6 seconds, and most preferably 5 seconds. It is also desirable to use the press at room temperature without heating. The thickness S of the spacer may be within the range of the thickness of the window member × 0.7≦S≦(H-Tave1) or within the range of the thickness of the window member × 0.75≦S≦(H-Tave1). The spacer thickness S (unit: mm) may be within the range of the window member thickness (unit: mm) -0.3≦S≦(H-Tave1), the window member thickness (unit: mm) -0.2≦S≦(H-Tave1), or the window member thickness (unit: mm) -0.1≦S≦(H-Tave1). The spacer thickness S may be within the range of (second sheet thickness + window member thickness) × 0.3≦S≦(H-Tave1), or the range of (second sheet thickness + window member thickness) × 0.4≦S≦(H-Tave1). The pressing step reduces variations in the in-plane thickness of the polishing layer and corrects unevenness in the adhesive layer. Furthermore, air pockets present between the window member and the second sheet are removed, allowing the window member to be tightly fixed to the surface of the second sheet.

[0064] <Second Aspect> A method for manufacturing a polishing pad according to a second aspect of the present invention includes the steps of: preparing a first sheet having a polishing surface and a surface opposite to the polishing surface (opposite surface); and a second sheet having an adhesive on at least one surface of the sheet; forming a first through hole penetrating the first sheet in a thickness direction from the polishing surface to the opposite surface; bonding the first sheet and the second sheet together such that the opposite surface of the first sheet and the surface of the second sheet having the adhesive face each other; arranging a film in the first through hole of the first sheet to which the second sheet has been bonded, wherein the film is a colored film and has substantially the same shape as the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and acquiring position information of the first through hole. a step of forming a second through hole penetrating the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side based on the acquired position information, wherein the second through hole is formed such that the outer periphery of the second through hole is covered by the outer periphery of the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side, and a step of removing the film after forming the second through hole and placing a window member within the first through hole and on the adhesive-bearing surface of the second sheet. The respective steps and components in the manufacturing method of the polishing pad of the second aspect can be the same as those described in the manufacturing method of the first aspect, particularly in "1. Step of preparing a polishing pad". For example, this manufacturing method may further include a step of preparing a cutting processing device including: an imaging unit that, when the polished surface of the first sheet is on the upper side, photographs the first sheet from above the polished surface of the first sheet; a control unit that identifies the position of a first through hole from the image photographed by the imaging unit and, based on the information on the identified position of the first through hole, commands the formation of a second through hole that penetrates the second sheet within the first through hole when viewed in the thickness direction from the polished surface side of the first sheet; and a hole forming unit that forms the second through hole in accordance with the command of the control unit, and the step of acquiring the position information may include the control unit identifying the position of the first through hole from the image photographed by the imaging unit.The step of acquiring the position information may also include the control unit identifying the position of the film by identifying the color difference between the film and the polishing surface in the image captured by the photographing unit. In the manufacturing method of the second aspect, by manufacturing the polishing pad using a colored film, the position of the first through hole can be easily identified, and the second through hole can be formed within the first through hole based on the position information. This reduces the amount of manual manual operation required and allows for simple and efficient manufacturing of polishing pads with endpoint detection windows. Furthermore, the influence of manual operation errors can be reduced, improving yield. Furthermore, using a film can prevent dust and dirt from adhering between the window member and the exposed portion of the second sheet during manufacturing of the polishing pad, thereby reducing the risk of the window member peeling off.

[0065] <Method of Use> When using a polishing pad manufactured by the method of the present invention, the polishing pad is attached to the polishing table of a polishing machine so that the polishing surface of the first sheet faces the workpiece. Then, while supplying slurry, the polishing table is rotated to polish the workpiece surface. Due to the centrifugal force generated during the polishing process and entering the first through-hole, the polishing debris moves to the side of the first through-hole. This makes it difficult for polishing debris to accumulate near the center of the window member, enabling optical detection over a long period of time. Examples of workpieces that can be polished using a polishing pad manufactured by the method of the present invention include bare silicon and semiconductor devices. Among these, the polishing pad manufactured by the method of the present invention is particularly suitable for polishing semiconductor devices, particularly for finish polishing, and is therefore preferred.

[0066] Using a polishing pad manufactured by the method of the present invention, for example, by irradiating a substrate with light from a light source through a window member and analyzing the interference signal generated by reflection from the surface of the substrate, it is possible to optically detect the surface characteristics of the polished object, such as a semiconductor wafer, and the point in time when the polished object has reached a flat state while polishing the object.

[0067] (Advantages) According to the first aspect of the present invention, by placing a spacer of a predetermined thickness around the polishing pad and pressing it, it is possible to prevent the polishing pad from being crushed while increasing the adhesion between the back surface of the window member of a polishing pad with an endpoint detection window (window member) and the adhesive surface of the second sheet. This makes it possible to manufacture a polishing pad in which the window member is less likely to peel off from the polishing pad. Furthermore, because the window member is fixed in close contact with the adhesive surface, it is possible to suppress slurry penetration. Furthermore, the problem of uneven wear during polishing is less likely to occur. Furthermore, in the first aspect of the present invention, the press treatment can reduce variation in the depth from the polishing surface to the top surface of the window member between lots and within the polishing pad, thereby stabilizing the quality of light transmission. Furthermore, because the window member can be installed flat, slurry and polishing debris are smoothly discharged by centrifugal force during polishing, making it less likely for slurry and polishing debris to remain on the surface of the window member. Furthermore, by manufacturing a polishing pad using a colored film, the position of the first through hole can be easily identified, and the second through hole can be formed within the first through hole based on the position information. This reduces the amount of manual operation required by humans, allowing for simple and efficient manufacturing of polishing pads with endpoint detection windows. Furthermore, the influence of errors due to manual operation can be reduced, improving yield. Furthermore, the use of a film can prevent dust and dirt from adhering between the window member and the exposed portion of the second sheet during polishing pad manufacturing, further reducing the risk of window member peeling. According to the second aspect of the present invention, a polishing pad with an endpoint detection window can be efficiently manufactured using a simpler method than conventional methods. Furthermore, the method of the present invention leaves the film in the first through hole after bonding the first sheet and the second sheet together until the window member is placed, thereby reducing the risk of dust and dirt adhering to the adhesive surface of the second sheet exposed in the first through hole. This reduces the problem of the window member peeling from the polishing pad during polishing. In addition, the first sheet is photographed by the photographing unit, and the control unit identifies the position of the first through hole from the image.Based on this position information, the hole forming unit can accurately and efficiently form the second through hole within the first through hole when viewed in the thickness direction from the polishing surface.

[0068] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0069] Example 1: A resin-containing solution was obtained by adding 60 parts by weight of DMF and 5 parts by weight of water to 100 parts by weight of a solution containing 30 parts by weight of a polyester-based polyurethane resin with a 100% modulus of 7.8 MPa and 70 parts by weight of DMF. The resulting resin-containing solution was filtered to remove insoluble components. The solution was cast onto a polyester sheet using a knife coater to a uniform coating thickness. The polyester sheet onto which the resin-containing solution had been cast was then immersed in a coagulation bath (the coagulation liquid was water) to coagulate the resin-containing solution. The polyester sheet was then peeled off, washed, and dried to obtain a polyurethane first sheet. The surface of the resulting first sheet was buffed to a thickness of 1.07 mm, and a 0.188 mm thick PET resin substrate was bonded to the side opposite the buffed surface with an adhesive. The first sheet was embossed from the front side to form a grid pattern of grooves with a rectangular cross section, each with a groove width of 1 mm, a groove spacing of 4 mm, and a groove depth of 0.7 mm. The grooved first sheet was cut into 800 mm squares and placed in a predetermined position on the cutting machine (hole forming unit) with the groove-treated surface facing up. Drawing data in which 25 mm diameter circles were arranged at 120° intervals on a 381 mm diameter circle was input into a personal computer (controller) in advance, and then the input data from the personal computer was output to a linked cutting machine and cut to form first through holes. A double-sided tape (a second sheet (a double-sided adhesive tape with a polyethylene terephthalate core), 0.242 mm) having release paper on one side was attached to the side of the resin substrate to which the first sheet was not attached using a laminator, and the first sheet was again placed in a predetermined position on the cutting machine. A film made of release paper cut into a 24 mm diameter circle by a cutting machine on the adhesive surface exposed to the first through holes was inserted into the three first through holes. The entire first sheet was photographed with a camera installed above the first sheet, and the position information of the first through hole was obtained based on the color shading of the first sheet and the film, and a second through hole with a diameter of 9 mm was cut at the center of the first through hole. At this time, the center of the first through hole and the center of the second through hole were programmed to be the same.Furthermore, a center position equidistant from the three first through holes was identified from the position coordinates of the first through holes, and the pad was cut into a circle with a diameter of 762 mm centered on that position using a cutting machine. A 0.4 mm thick acrylic plate with a roughened surface was prepared as a window member, and cut to a diameter of 24 mm using a cutting machine. The film inside the first through hole was removed, and the window member was inserted so that the roughened surface was facing up. The first sheet was placed in a predetermined position in a press (an apparatus used for embossing), and 0.3 mm thick spacers were placed at the four corners of the press. The entire pad was pressed at a pressure of 0.3 MPa for 5 seconds to press the window member, thereby producing a polishing pad with a window member.

[0070] [Example 2] A polishing pad with a window member was manufactured in the same manner as in Example 1, except that the thickness of the first sheet after buffing was 1.28 mm, the 0.188 mm PET substrate was replaced with a 0.678 mm polyurethane resin-impregnated nonwoven fabric substrate, the thickness of the acrylic plate serving as the window member was 0.8 mm, and the thickness of the spacer was 1.5 mm.

[0071] Comparative Example 1 A polishing pad was produced in the same manner as in Example 2, except that pressing with a press was not carried out after fitting the window member.

[0072] Comparative Example 2 A polishing pad was produced in the same manner as in Example 1, except that pressing was carried out without using a spacer.

[0073] Comparative Example 3 A polishing pad was produced in the same manner as in Example 1, except that the thickness of the spacer was 1.7 mm.

[0074] Comparative Example 4 A polishing pad was produced in the same manner as in Example 2, except that the pressure of the press was set to 1.0 MPa.

[0075] The appearance defects (pad crushing, adhesive overflow, air trapped between the window member and the adhesive surface) of Examples 1 and 2 and Comparative Examples 1 to 4 were checked, as well as the average depth from the polishing surface to the window upper surface before and after pressing, and the difference between the maximum and minimum depths from the polishing surface to the window upper surface before and after pressing. The difference between the maximum and minimum depths from the polishing surface to the window upper surface indicates the degree of variation in the depth from the polishing surface to the window upper surface, and the smaller the difference between the maximum and minimum depths, the smaller the variation and the more preferable it is. Note that H, Tave1, Tave2, and Tmax were determined as follows. H: The thickness of the polishing pad was measured in accordance with Japanese Industrial Standards (JIS K 6505) using a Schopper-type thickness meter (pressure surface: circular with a diameter of 1 cm). Specifically, three 10 cm x 10 cm sample pieces were prepared by cutting the first sheet remaining after cutting the polishing pad into a circular shape in the cutting process. Each sample piece was set in a predetermined position in a thickness measuring instrument, and a pressure surface with a load of 100 g / cm was placed on the surface of the sample piece. After 5 seconds, the thickness was measured. The thickness was measured at five locations on each sample piece and the arithmetic mean was calculated. Furthermore, the arithmetic mean of three sample pieces was also calculated. If it is difficult to obtain three 10 cm x 10 cm sample pieces due to the size of the polishing pad, the thickness of the polishing pad may be measured at 15 locations within the polishing pad and the arithmetic mean was calculated. Tave 1: For each of the three window members before pressing, the depth from the polishing surface to the top surface of the window member was measured using a depth gauge at four locations on the outer periphery of the top surface of the window member and one location in the center. The arithmetic mean of the 15 depth measurements was calculated and defined as Tave 1. Tave2: For each of the three window members after pressing, the depth from the polished surface to the top surface of the window member was measured using a depth gauge at four locations on the outer periphery of the top surface of the window member and one location in the center, and the arithmetic average of the 15 depth measurements was calculated to obtain Tave2. Tmax1: The largest value of the depths from the polished surface to the top surface of the window member at 15 locations was determined when calculating Tave1. Tmin1: The smallest value of the depths from the polished surface to the top surface of the window member at 15 locations was determined when calculating Tave1. Tmax2: The largest value of the depths from the polished surface to the top surface of the window member at 15 locations was determined when calculating Tave2.Tmin2: The smallest value of the depth from the polished surface to the upper surface of the window member at 15 locations when calculating Tave2 was found.

[0076]

[0077] In the table, the appearance defects were evaluated based on the presence or absence of air trapped between the adhesive surface of the exposed portion of the second sheet and the window member, the adhesive protruding into the inside of the second through-hole, and the crushed pad (air bubbles in the pad are crushed by pressing, and the crushed shape does not fully return to normal even after pressing). If one or more of these were present, it was determined that there was an appearance defect.

[0078] In Comparative Example 1, in which pressing was not performed, the maximum and minimum depths from the polished surface to the window surface were as large as 30 μm, and air was present between the back surface of the window member and the adhesive surface of the exposed portion of the second sheet, preventing the window member from adhering to the exposed portion. In this case, slurry seeped between the window member and the exposed portion during polishing, making the window member more likely to peel off. In Comparative Example 2, in which pressing was performed without using a spacer, the window member was pressed too far with the press, causing the adhesive to protrude into the second through-holes, which serve as light-transmitting portions, thereby undesirably impeding light transmission. In Comparative Example 3, in which the spacer was thick and the amount of depression of the press was small, the window member did not come into contact with the upper surface plate, and air was trapped between the window member and the adhesive surface. In this case, as in Comparative Example 1, the window member was more likely to peel off during polishing. In Comparative Example 4, where the pressing pressure was high, the change in Tave (Tave1 - Tave2) was large at 53 μm, and the depth from the polishing surface to the upper surface of the window after pressing was significantly smaller than before pressing, indicating pad crushing. The polishing pad of Comparative Example 4, where pad crushing was observed, had the disadvantage of a reduced pad thickness, resulting in a shorter product life than usual. There were also problems such as higher density than usual and a reduction in compression recovery due to plastic deformation, making polishing scratches more likely to occur. On the other hand, in Examples 1 and 2, the change in Tave (Tave1 - Tave2) was 9 μm and 16 μm, respectively, indicating little variation in the depth from the polishing surface to the window surface before and after pressing. The pressing reduced the range between the maximum and minimum values ​​of the depth from the polishing surface to the window surface, thereby reducing depth variation. Furthermore, no external defects such as air entrapment between the adhesive surface of the exposed portion and the window member, adhesive spillage into the inside of the second through hole, or pad crushing were observed. Therefore, it was judged that the polishing pad was practical, and the durability (peel prevention performance) of the window member was further tested.

[0079] <Window Member Durability Verification Test> To confirm the durability of the window adhesive state, an accelerated dressing test was performed on the pad of Example 1 under high dressing pressure conditions of 60 N, which is six times the normal pressure condition, until the pad was worn down to 600 μm. (Dressing Conditions) Polishing machine used: Speedfam, product name "FAM-12BS" Platen rotation speed (polishing pad rotation speed): 30 rpm Slurry: pure water Flow rate: 80 ml / min Dresser: 3M diamond dresser, model number "A188" Dresser rotation speed: 30 rpm Dressing pressure: 60 N

[0080] When the polishing pad is worn down by 600 μm in an accelerated test, the upper part of the window member approaches the polishing surface, which can cause the surface of the window member to come into contact with the dresser. In fact, scratches caused by contact with the dresser were confirmed on the surface of the window member of Example 1 after the test. However, even when the pad was worn down beyond its normal use limit under such high pressure and came into contact with the dresser, the window member did not peel off with the polishing pad of Example 1, demonstrating that the window member was sufficiently fixed. In addition, the entire polishing pad after dressing (four diameters at 45-degree angle differences, i.e., the ranges on lines in the north-south, northeast-southwest, east-west, and southeast-northwest directions (Line A, Line B, Line C, and Line D) from the center of the pad) and a 70 mm radius range from the center of the end point detection window (four diameters at 45-degree angle differences, i.e., the ranges on lines in the north-south, northeast-southwest, east-west, and southeast-northwest directions (Line A, Line B, Line C, and Line D) from the center of the window) were observed with a laser microscope (VK-X1000, manufactured by KEYENCE Corporation), and height information profile measurements were performed based on the obtained laser images (Figures 8 to 11). As a result, no abnormal unevenness was observed in the profile (≒ roughness curve) of the entire pad or around the window member, and there was no uneven wear of the pad due to the window member. Note that Figure 8 shows the pad thickness of the entire pad in Example 1. 9 to 11 are diagrams showing the pad thickness around each of the three window members of the polishing pad of Example 1. It can be seen from Fig. 8 that there are no abnormal irregularities around the entire pad of Example 1. It can also be seen from Figs. 9 to 11 that there are no abnormal irregularities around the window member of Example 1.

[0081] According to the present invention, the pad is not significantly crushed when pressed, and the adhesion between the back surface of the window member of a polishing pad with an endpoint detection window (window member) and the adhesive surface of the second sheet can be improved. This makes it possible to manufacture a polishing pad in which the window member is less likely to peel off from the polishing pad. Furthermore, according to the present invention, a polishing pad with an endpoint detection window can be manufactured simply and efficiently, reducing the amount of manual operation required by humans. Therefore, the method of the present invention is extremely useful industrially.

[0082] DESCRIPTION OF SYMBOLS 1... Polishing pad 2... First sheet 3... Second sheet 4... Window member 4'... Top of window member 5... First through hole 5'... Outer periphery of first through hole 6... Second through hole 6'... Outer periphery of second through hole 7... Exposed portion 8... Groove 8'... Bottom of groove 9... Object to be polished 10... Polishing debris 11... Centrifugal force 12... Film 13... Polishing layer 14... Base layer 15... Spacer 16... Lower surface plate of press machine 17... Upper surface plate of press machine 18... Pressing force

Claims

1. A polishing pad comprising a first sheet having a first through hole, a second sheet having a second through hole, and a window member, wherein the first sheet has a polishing surface for polishing an object to be polished, the second sheet is bonded to the surface of the first sheet opposite to the polishing surface, the second through hole is formed such that, when the first sheet is viewed in the thickness direction from the polishing surface side, the outer periphery of the second through hole is covered by the outer periphery of the first through hole, and the window member is disposed within the first through hole and on the second sheet so that, when the polishing surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface, the uppermost part of the window member is lower than the polishing surface, the method comprising the steps of: preparing the polishing pad; and placing the polishing pad on a lower platen of a press having an upper platen and a lower platen, placing spacers of a predetermined thickness on the lower platen around the polishing pad, and pressing the polishing pad with the press, The manufacturing method, wherein the thickness S of the spacer is within the range of the thickness of the second sheet≦S≦(H−Tave1), and the pressing pressure is 0.8 MPa or less (where S is the thickness of the spacer, H is the thickness of the polishing pad before pressing, and Tave1 is the average depth from the polishing surface to the upper surface of the window member before pressing).

2. The manufacturing method according to claim 1, further comprising pressing the polishing pad with a press so that |Tave1 - Tave2| ≦ 40 μm (where Tave1 is the average depth from the polishing surface to the upper surface of the window member before pressing, and Tave2 is the average depth from the polishing surface to the upper surface of the window member after pressing).

3. The step of preparing a polishing pad includes the following steps: preparing a first sheet having a polishing surface and a surface opposite to the polishing surface (opposite surface), and a second sheet having an adhesive on at least one surface of the sheet; forming a first through hole penetrating the thickness direction from the polishing surface of the first sheet to the opposite surface; bonding the first sheet and the second sheet together so that the opposite surface of the first sheet and the surface of the second sheet having the adhesive face each other; arranging a film in the first through hole of the first sheet to which the second sheet is bonded, wherein the film is a colored film and has approximately the same shape as the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and acquiring position information of the first through hole.

2. The manufacturing method according to claim 1, comprising: a step of forming a second through hole penetrating the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side based on the acquired position information; wherein the second through hole is formed such that an outer periphery of the second through hole is covered by an outer periphery of the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and a step of removing the film after forming the second through hole and placing a window member within the first through hole and on the adhesive-bearing surface of the second sheet.

4. The manufacturing method according to claim 3, wherein the film has a color different from the color of the polished surface of the first sheet, and the step of acquiring the position information includes identifying the position of the first through hole by utilizing the difference in color between the film and the polished surface.

5. A manufacturing method as described in claim 3, further comprising the step of preparing a cutting device comprising: a photographing unit that photographs the first sheet from above the polished surface of the first sheet when the polished surface of the first sheet is placed on top; a control unit that identifies the position of a first through hole from the image photographed by the photographing unit and, based on information about the identified position of the first through hole, commands the formation of a second through hole that penetrates the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polished surface side; and a hole forming unit that forms the second through hole in accordance with instructions from the control unit, wherein the step of acquiring the position information includes the control unit identifying the position of the first through hole from the image photographed by the photographing unit.

6. The manufacturing method described in claim 5, wherein the step of acquiring the position information includes the control unit identifying the position of the film by identifying the difference in color between the film and the polished surface in the image captured by the photographing unit.

7. A manufacturing method as described in claim 5, wherein the step of forming the second through hole includes the hole forming unit forming a second through hole that penetrates the second sheet within the first through hole when viewing the first sheet in the thickness direction from the polishing surface side, based on the acquired position information of the first through hole.

8. A manufacturing method as described in claim 3 or 5, wherein the step of forming the second through hole includes forming the second through hole based on position information of the first through hole so that the center of the first through hole and the center of the second through hole are approximately the same when viewing the first sheet in the thickness direction from the polishing surface side.

9. A manufacturing method as described in claim 3 or 5, further comprising a step of acquiring information on positions (equidistant positions) that are equidistant from the centers of all first through holes when the first sheet is viewed in the thickness direction from the polishing surface side based on the position information of the first through holes, and a step of cutting the first sheet to which the second sheet is attached into a circle with an arbitrary radius, centered on the equidistant position, so as to encompass the first through holes, based on the equidistant position information.

10. A manufacturing method according to claim 3 or 5, wherein the shape of the first through hole and the shape of the second through hole when viewed in the thickness direction from the polishing surface side of the polishing pad are both circular.

11. The manufacturing method according to claim 3 or 5, wherein the circle-equivalent diameter of the first through hole is 5 to 30 mm larger than the circle-equivalent diameter of the second through hole.

12. The method of claim 3 or 5, further comprising the step of providing grooves (e.g., embossed grooves) in the abrasive surface of the first sheet.

13. A manufacturing method as described in claim 3 or 5, wherein the step of positioning the window member includes positioning the window member so that, when the polished surface is the upper surface and the surface of the second sheet opposite to the surface bonded to the first sheet is the lower surface, the top of the window member is higher than the bottom of the groove.

14. A method for manufacturing a polishing pad, comprising the following steps: preparing a first sheet having a polishing surface and a surface opposite to the polishing surface (opposite surface), and a second sheet having an adhesive on at least one surface of the sheet; forming a first through hole penetrating the thickness direction from the polishing surface of the first sheet to the opposite surface; bonding the first sheet and the second sheet together so that the opposite surface of the first sheet and the surface of the second sheet having the adhesive face each other; arranging a film in the first through hole of the first sheet to which the second sheet is bonded, wherein the film is a colored film and has approximately the same shape as the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and acquiring position information of the first through hole. a step of forming a second through hole penetrating the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side based on the acquired position information, wherein the second through hole is formed such that the outer periphery of the second through hole is covered by the outer periphery of the first through hole when the first sheet is viewed in the thickness direction from the polishing surface side; and a step of removing the film after the second through hole is formed, and placing a window member within the first through hole and on the adhesive-bearing surface of the second sheet.

15. A manufacturing method as described in claim 14, further comprising the step of preparing a cutting device including: a photographing unit that photographs the first sheet from above the polished surface of the first sheet when the polished surface of the first sheet is placed on top; a control unit that identifies the position of a first through hole from the image photographed by the photographing unit and, based on information about the identified position of the first through hole, commands the formation of a second through hole that penetrates the second sheet within the first through hole when the first sheet is viewed in the thickness direction from the polished surface side; and a hole forming unit that forms the second through hole in accordance with instructions from the control unit, and wherein the step of acquiring the position information includes the control unit identifying the position of the first through hole from the image photographed by the photographing unit.

16. The manufacturing method described in claim 15, wherein the step of acquiring the position information includes the control unit identifying the position of the film by identifying the difference in color between the film and the polished surface in the image captured by the photographing unit.

Images