Polishing pad

Abstract

The present invention suppresses waviness generated in boundary parts of air bags in a holding plate.　A polishing pad 3 comprises: a polishing layer 11 on which a polishing surface for polishing an object 2 to be polished is formed; and a base material layer 12 provided on the side opposite to the polishing surface of the polishing layer 11. The polishing surface of the polishing layer 11 has at least one surface structure selected from the group consisting of lattice grooves, radial grooves, spiral grooves, concentric circular grooves, and through-holes, and an adhesive surface of the base material layer 12 on the polishing layer side has at least one surface structure selected from the group consisting of lattice grooves, radial grooves, spiral grooves, concentric circular grooves, and through-holes.

Description

Polishing pad

[0001] The present invention relates to a polishing pad, and more specifically to a polishing pad having a polishing layer on which a polishing surface for polishing an object to be polished is formed, and a base layer provided on the opposite side of the polishing surface of the polishing layer and held on a polishing platen.

[0002] Conventionally, when polishing a workpiece such as a semiconductor substrate, a disc-shaped polishing pad is used, which has a polishing layer on which a polishing surface is formed and a base layer provided on the opposite side of the polishing surface of the polishing layer. The polishing pad is mounted on the polishing platen of the polishing apparatus, while the workpiece is held on a holding platen (Patent Document 1). In the polishing apparatus, so-called chemical mechanical polishing (CMP) is performed by pressing the workpiece against the polishing pad, rotating the holding platen and the polishing platen relative to each other, and further supplying a slurry containing chemical components between the workpiece and the polishing pad. It is known that the amount of polishing of the workpiece in CMP can be increased by increasing the polishing pressure, and in the polishing apparatus of Patent Document 1, multiple airbags are provided concentrically on the holding platen, and the pressure is adjusted for each of the multiple regions divided in the radial direction of the workpiece, thereby adjusting the pressure that the polishing platen acts on the workpiece and improving the flatness of the workpiece.

[0003] Special Publication No. 2008-528300

[0004] The amount of polishing a workpiece in CMP is affected by various polishing conditions, but as a general trend, the relationship between the amount of polishing and the polishing conditions can be expressed by Preston's equation, shown in (Equation 1) below. Preston's equation: RR = k・P・v (Equation 1) Here, RR is the polishing rate, P is the pressure applied to the workpiece against the polishing pad (polishing pressure), v is the relative velocity between the workpiece and the polishing pad, and k is an empirical parameter that depends on the type of slurry, temperature, etc. As can be seen from (Equation 1) above, the amount of polishing and the polishing pressure are proportional. For this reason, in semiconductor device manufacturing, increasing the polishing pressure is often used to improve manufacturing throughput. Thus, it is known that the amount of polishing a workpiece in CMP can be increased by increasing the polishing pressure. In the polishing apparatus of Patent Document 1, multiple airbags are provided concentrically on the holding platen, and the pressure is adjusted for each of the multiple regions divided in the radial direction of the workpiece, thereby adjusting the pressure that the polishing platen acts on the workpiece and improving the flatness of the workpiece. However, when concentric airbags are provided on the holding platen, the pressing force on the workpiece becomes lower at the boundary between adjacent airbags, and the repulsive force from the polishing pad pressed by the workpiece concentrates on the portion corresponding to this boundary. As a result, the portion of the workpiece corresponding to the boundary is over-polished, and concentric, wavy irregularities are formed in the radial direction of the workpiece (see Figure 5). The inventors of this application have decided to refer to such irregularities originating from the boundary portions of the airbags on the holding platen as "wavy." In view of these problems, the present invention provides a polishing pad that can suppress polishing defects (wavy) that occur at the boundary portions of the airbags on the holding platen.

[0005] The polishing pad according to claim 1 comprises a polishing layer having a polishing surface for polishing an object to be polished, and a base layer provided on the side opposite to the polishing surface of the polishing layer, wherein the polishing surface of the polishing layer has at least one surface structure selected from the group consisting of grid grooves, radial grooves, spiral grooves, concentric grooves, and through holes, and the adhesive surface of the base layer on the polishing layer side has at least one surface structure selected from the group consisting of grid grooves, radial grooves, spiral grooves, concentric grooves, and through holes. The polishing pad according to claim 5 is a polishing pad according to the invention described in claim 1, wherein a polishing layer side concentric groove is formed on the polishing surface of the polishing layer, which is composed of a plurality of concentric circular grooves, and is characterized in that a base layer side concentric groove is formed on at least one surface of the base layer, which is the adhesive surface on the polishing layer side, which is the holding surface on the polishing platen side, or which is the adhesive surface on the base layer side of the polishing layer, and the center of the polishing layer side concentric groove is separated from the center of the base layer side concentric groove, so that in a plan view, a plurality of intersection points are formed in the circular grooves that constitute the polishing layer side concentric groove, which intersect with the base layer side concentric groove. The polishing pad according to claim 13 is characterized in that, in the invention described in claim 1, a plurality of radial grooves are formed radially on at least one surface of the adhesive surface on the polishing layer side of the base layer, the adhesive surface on the base layer side of the polishing layer, or the holding surface on the polishing platen side of the base layer, and the ends of the radial grooves on the central side of the base layer or the polishing layer are separated from each other to form a flat portion in the central part of the base layer or the polishing layer.

[0006] According to the invention of claim 1, it is possible to provide a polishing pad that can suppress polishing defects (wavy) that occur at the boundary of the airbag in the holding platen. According to the invention of claim 5, when the polishing pad is viewed from a plan view, the concentric grooves on the base layer side intersect the circular grooves on the polishing layer side at multiple locations, so that the repulsive force from the polishing pad can be dispersed when the workpiece to be polished is pressed against the polishing pad. As a result, the repulsive force from the polishing pad does not concentrate at the part of the workpiece corresponding to the boundary of the airbag in the holding platen, and the occurrence of wavy can be suppressed. According to the invention of claim 13, by providing the radial grooves on at least one surface of the adhesive surface of the base layer, the holding surface of the base layer, or the adhesive surface of the polishing layer, when the workpiece to be polished is pressed against the polishing pad, the stress on the polishing pad is dispersed by the radial grooves, and the repulsive force from the polishing pad does not concentrate at the part corresponding to the boundary of the airbag in the holding platen. As a result, the occurrence of wavy can be suppressed.

[0007] Graphs illustrating the polishing apparatus, cross-sectional view of the polishing apparatus and polishing pad, diagram illustrating the airbag of the holding platen, diagram illustrating the combination of surface structure patterns used on the polishing surface of the polishing pad and the adhesive surface on the polishing layer side of the base layer, schematic diagram illustrating wavy, perspective view of the polishing apparatus, cross-sectional view of the polishing apparatus and polishing pad, diagram illustrating the airbag of the holding platen, plan view of the area near the center of the polishing pad, diagram illustrating the intersection of the concentric grooves on the polishing layer side and the concentric grooves on the base layer side, graph relating to the maximum number of intersections, graph evaluating the wavy of the workpiece polished by the polishing pad, graph showing the surface state of the workpiece polished by the polishing pad, diagram illustrating the suppression of wavy generation, diagram illustrating the generation of wavy, plan view of the polishing pad according to the second embodiment, cross-sectional view of the polishing pad according to the third embodiment, cross-sectional view of the polishing pad according to the fourth embodiment, perspective view of the polishing apparatus, cross-sectional view of the polishing apparatus and polishing pad, plan view of the base layer of the polishing pad, plan view of the base layer of the polishing pad according to the sixth embodiment, cross-sectional view of the polishing pad according to the seventh embodiment, diagram showing experimental results regarding the amount of wavy, regarding the surface state of the workpiece Figure 8 shows experimental results of the following: Cross-sectional view of a polishing pad according to an embodiment of the present invention Perspective view of a polishing apparatus Cross-sectional view of the polishing apparatus and polishing pad Diagram illustrating the airbag of the holding platen Plan view of the passage area E through which the workpiece to be polished passes in the adhesive layer when polishing Plan view of a group of radial grooves formed in the adhesive layer Plan view of a group of concentric grooves formed in the adhesive layer Plan view of a group of grooves formed in the adhesive layer that combine grid grooves and spiral grooves Plan view of a group of grooves formed in the adhesive layer that combine radial grooves and through holes Dispect view of a polishing apparatus Cross-sectional view of a polishing apparatus and polishing pad Diagram illustrating the airbag of the holding platen Perspective view of the height change surface when viewed from the surface (or back) side of the base material layer according to an embodiment of the present invention Explanatory diagram of profile processing used in an embodiment of the present invention Explanatory diagram of the result of profile processing used in an embodiment of the present invention A schematic diagram of a side view of a peak M having a height-changing ridge and a valley V having a height-changing inclined surface in an embodiment of the present invention, and a peak M having a height-changing ridge and a valley V having a height-changing inclined surface,A schematic diagram of the base material layer as seen from the surface (or back) side of the base material layer according to the embodiment of Figure 11 A perspective view of a portion of the base material layer as seen from the surface (or back) side of the base material layer according to the embodiment of Figure 11 A perspective view showing the polishing device Cross-sectional view of the polishing device and polishing pad A plan view of the base material layer as seen from the surface (or back) side of the base material layer according to the embodiment of Figure 12 A main part of the base material layer in the embodiment of Figure 12 where stress is applied to the base material layer and the cut portion has expanded Plan view of the base material layer according to the embodiment of Figure 13 ( Plan view of the main part when viewed from the front side (or back side) of the base material layer 12 according to the embodiment of the 13 embodiment when stress is applied to the base material layer and the cut portion is widened Plan view of the main part when viewed from the front side (or back side) of the base material layer 12 according to the embodiment of the 14 embodiment when stress is applied to the base material layer and the cut portion is widened Plan view of the main part when viewed from the front side (or back side) of the base material layer 12 according to the embodiment of the 15 embodiment Plan view of the main part when viewed from the front side (or back side) of the base material layer 12 according to the embodiment of the 16 embodiment,

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a perspective view of a polishing apparatus 1 equipped with a polishing pad 3 used for polishing an object to be polished 2 such as a semiconductor substrate, which is one embodiment of the present invention, and Figure 2 is a cross-sectional view of the polishing apparatus 1 and the polishing pad 3. Note that the dimensions of each part in the following figures are exaggerated for illustrative purposes.

[0009] The polishing apparatus 1 comprises a polishing platen 4 located below to support the polishing pad 3, a holding platen 5 located above to support the workpiece 2, and a slurry supply means 6 for supplying slurry S. The polishing pad 3 and the workpiece 2 are each substantially disc-shaped, and the polishing pad 3 has a larger diameter than the workpiece 2. A polishing surface is formed on the upper surface of the polishing pad 3 to contact and polish the workpiece 2, and the lower surface of the polishing pad 3 is fixed to the polishing platen 4 by double-sided tape or the like.

[0010] As shown in Figure 2, the holding platen 5 comprises a disc-shaped top ring 5a, an airbag A consisting of multiple concentrically arranged compartments on the lower surface of the top ring 5a, and an annular retainer 5b that holds the airbag A and the outer periphery of the workpiece 2 to be polished. The disc-shaped workpiece 2 is held in close contact with the lower surface of the airbag A inside the retainer 5b.

[0011] The polishing platen 4 and the holding platen 5 are each rotated by a driving means (not shown), and the holding platen 5 is further reciprocated radially from the center position of the polishing platen 4. As a result, the workpiece 2 held by the holding platen 5 slides radially along the polishing surface of the rotating polishing pad 3 while rotating.

[0012] The slurry supply means 6 supplies a slurry, in which abrasive particles are mixed in the required liquid, to the polishing surface of the polishing pad 3. This causes the slurry to penetrate between the polishing surface and the workpiece 2, thereby performing so-called chemical mechanical polishing (CMP).

[0013] Next, with reference to Figure 3, which is a bottom view of airbag A, the configuration of airbag A provided on the holding platen 5 will be described. As shown in Figure 3, the holding platen 5 is equipped with first to sixth airbags A1 to A6 arranged concentrically on the lower surface of the top ring 5a, and consists of a cylindrical first airbag A1 located in the center and ring-shaped second to sixth airbags A2 to A6 surrounding the first airbag A1. Each of the first to sixth airbags A1 to A6 has a roughly rectangular cross-section, and the flat lower surface is processed to allow it to adhere closely to and hold the surface of the workpiece 2 to be polished. Different pressures (P1 to P6) can be applied to the workpiece 2 to be polished from each of the first to sixth airbags A1 to A6.

[0014] The pressure applied to the first to sixth airbags A1 to A6 can be adjusted according to the workpiece 2 to be polished and various polishing conditions. Since such a holding plate 5 is known from the aforementioned Patent Document 1, further detailed explanation will be omitted.

[0015] As shown in Figure 2, the polishing pad 3 comprises a polishing layer 11 having a polishing surface that contacts the object to be polished 2, a base layer 12 provided on the side of the polishing layer 11 opposite to the polishing surface and held by the polishing platen 4, and an adhesive layer 13 that bonds the polishing layer 11 and the base layer 12.

[0016] A polyurethane sheet can be used for the polishing layer 11. As such a polyurethane sheet, a foamed polyurethane sheet can be used, which is formed by mixing an isocyanate-terminated prepolymer (hereinafter sometimes simply referred to as prepolymer), a curing agent, and a hollow body to form a polyurethane resin molded body, and then slicing the polyurethane resin molded body, and which has countless voids formed inside. Here, a polyurethane sheet refers to a polyurethane-based resin containing polyurethane and polyurethane polyurea.

[0017] A urethane sponge can be used for the base layer 12, and commercially available urethane sponges can be used as such. Alternatively, the same polyurethane sheet as the abrasive layer 11 may be used as the base layer 12.

[0018] The adhesive layer 13 is formed by applying a pressure-sensitive adhesive, such as an acrylic adhesive, to the front and back surfaces of a core material made of polyethylene terephthalate (PET). There are no particular restrictions on the adhesive layer 13, and it can be arbitrarily selected from double-sided tapes known in the art.

[0019] The polyurethane sheet used for the polishing layer 11 has a thickness of 0.5 to 2 mm, a Shore D hardness of 20.0 to 70.0, preferably 35.0 to 65.0, and a density of 0.60 to 1.10 g / cm³. ３ Each of these can be set accordingly. By setting the D hardness of the polishing layer 11 within the aforementioned range, the occurrence of scratches can be suppressed.

[0020] The urethane sponge used in the base layer 12 has a thickness of 0.5 to 2 mm, a Shore A hardness of 20.0 to 75.0, preferably 45.0 to 65.0, and a density of 0.20 to 0.70 g / cm³. ３ Each can be set accordingly.

[0021] Furthermore, the storage modulus (at 40°C) of the polishing layer 11 is 55 to 400 MPa, preferably 70 to 130 MPa, and the storage modulus (at 40°C) of the base layer 12 is 1 to 10 MPa, preferably 2 to 8 MPa. It is desirable that the ratio of the storage modulus of the polishing layer 11 to the storage modulus of the base layer 12 be in the range of 2 to 60, preferably 5 to 50. By setting it in this way, it becomes possible to polish the workpiece without damaging the edge shape of the workpiece.

[0022] The polishing surface of the polishing pad 3 and the adhesive surface of the base layer 12 on the polishing layer side are each formed with a surface structure having recesses containing grooves or holes of a specific pattern. In this embodiment, the polishing surface of the polishing pad 3 is provided with at least one surface structure selected from the group consisting of, for example, grid grooves, radial grooves, spiral grooves, concentric grooves, and through holes, and the adhesive surface of the base layer 12 on the polishing layer side is provided with at least one surface structure selected from the group consisting of, for example, grid grooves, radial grooves, spiral grooves, concentric grooves, and through holes. The selection of the surface structures on the polishing surface of the polishing pad 3 and the adhesive surface of the base layer 12 on the polishing layer side is arbitrary, and various combinations can be adopted. The surface structure of the adhesive surface of the base layer 12 on the polishing layer side is provided in a range that does not reach the outer circumference of the base layer 12 so that slurry does not penetrate into the adhesive layer 13 through the recesses.

[0023] In this embodiment, the surface structure provided on the base layer 12 is described as being provided on the adhesive surface on the polishing layer side. However, a similar surface structure may also be provided on the adhesive surface of the base layer 12 on the polishing platen side, or on the back surface of the polishing layer 11 (the adhesive surface on the base layer side). In these cases as well, it is possible to suppress polishing defects (wavy) that occur at the boundary of the airbag in the holding platen, just as when the surface structure is provided on the adhesive surface of the base layer 12 on the polishing layer side.

[0024] Figure 4 shows an example of a combination of multiple surface structure patterns used on the polishing surface of the polishing pad 3 and the adhesive surface on the polishing layer side of the base layer 12. The first row of Figure 4 schematically shows an example of the five types of surface structure patterns (from left to right: grid groove, radial groove, spiral groove, concentric groove, and through hole) applied to the adhesive surface on the polishing layer side of the base layer 12. On the other hand, the first column on the left of Figure 4 schematically shows an example of four of the five types of surface structure patterns (from top to bottom: grid groove, radial groove, spiral groove, and concentric groove) applied to the polishing surface of the polishing pad 3. In other words, Figure 4 illustrates 20 different patterns, which are combinations of the five types of surface structure patterns of the base layer 12 and the four types of surface structure patterns of the polishing pad 3. In each combination, the polishing pad is shown as viewed from above, with solid lines representing the surface structure of the polishing surface of the polishing layer 11 and dotted lines representing the surface structure of the base layer 12.

[0025] As shown in Figure 4, the surface structure patterns used in the polishing pad 3 and the base layer 12 may be the same or different, but it is preferable that the grooves, holes, and other recesses in both are offset from each other (for example, an arrangement where grooves intersect as much as possible, or where grooves (holes) are offset from each other). Therefore, when the same type and size of surface structure pattern is used in the polishing pad 3 and the base layer 12, the arrangement of the recesses in both surface structure patterns is offset by shifting the center position and orientation (rotation angle) of both surface structure patterns.

[0026] For example, when a grid groove is applied to the polishing layer 11 and a grid groove or radial groove is applied to the base layer 12, or vice versa, the grid lines and radial lines are made so as not to overlap, and the grid points and the centers of the radial lines are shifted vertically and horizontally so as not to overlap. Also, when radial grooves or helical grooves are applied to both the polishing layer 11 and the base layer 12, the center positions of each surface structure pattern are shifted, and the phases of the radial grooves or helical grooves in both surface structure patterns are shifted by relatively rotating both surface structure patterns. Furthermore, when helical grooves or concentric grooves are applied to both the polishing layer 11 and the base layer 12, the center positions of each surface structure pattern are shifted, for example, horizontally. On the other hand, in combinations of different surface structure patterns other than those mentioned above in Figure 4, if the recesses are offset (intersect) from each other even when simply overlapped, it is not necessary to shift the surface structures of the polishing layer 11 and the base layer 12.

[0027] Figure 2 shows a cross-sectional view along the grid groove 12a passing through the center of the polishing pad 3 when, among the combinations of surface structure patterns, concentric grooves 11a are used on the polishing surface of the polishing pad 3 and grid grooves 12a are used on the adhesive surface of the base layer 12 on the polishing layer side. In other words, in Figure 2, the center of the concentric groove 11a on the polishing surface is set to the center of the polishing pad 3, and one of the grid grooves 12a on the adhesive surface of the base layer 12 on the polishing layer side is arranged along the diameter of the polishing pad 3. The center of the concentric groove 11a on the polishing surface may be set eccentrically at a certain distance from the center of the polishing pad 3. The pitch between the concentric grooves 11a and the pitch between the grid grooves 12a, and the cross-sectional shape of the grooves 11a and 12a are arbitrary, but may be rectangular as shown in Figure 2.

[0028] When the polishing pad is viewed from a plan view, the grooves (recesses) formed in the polishing layer 11 and the grooves (recesses) formed in the base layer 12 intersect at multiple points. As a result, the repulsive force from the polishing pad is dispersed when the workpiece is pressed against the polishing pad. This prevents the repulsive force from the polishing pad from concentrating at the boundary positions of the first to sixth airbags A1 to A6 of the holding platen on the workpiece, thereby suppressing the occurrence of waviness.

[0029] The following describes the first to fourth embodiments. Figure 6 shows a perspective view of a polishing apparatus 102 equipped with a polishing pad 101 according to the present invention, which is used to polish an object to be polished 103 such as a semiconductor substrate. The polishing apparatus 102 includes a polishing platen 104 provided below to support the polishing pad 101, a holding platen 105 provided above to support the object to be polished 103, and a slurry supply means 106 for supplying slurry S. The polishing pad 101 and the object to be polished 103 each have a substantially disc shape, and the polishing pad 101 is formed to have a larger diameter than the object to be polished 103. A polishing surface is formed on the upper surface of the polishing pad 101 to contact and polish the object to be polished 103, and the lower surface of the polishing pad 101 is fixed to the polishing platen 104 by double-sided tape or the like. As shown in Figure 7, the holding platen 105 comprises a disc-shaped top ring 105a and a plurality of airbags A arranged concentrically on the lower surface of the top ring 105a, so that the disc-shaped workpiece 103 is held in close contact with the lower surface of the airbags A. The airbags A are also constructed to cover part or all of the holding platen 105 with a soft, flexible sheet (membrane) or the like (not shown) to the extent that it does not hinder the application of pressure to each different airbag A. The polishing platen 104 and the holding platen 105 rotate relative to each other by a driving means (not shown), and the holding platen 105 is provided to reciprocate radially from the center position of the polishing platen 104. As a result, the polishing pad 101 and the workpiece 103 slide relative to each other while rotating. The slurry supply means 106 supplies a slurry, in which abrasive particles are mixed in a required liquid, to the polishing surface of the polishing pad 101. This allows the slurry to penetrate between the polishing surface and the workpiece 103, thereby enabling so-called chemical mechanical polishing (CMP).

[0030] Figure 7 shows a cross-sectional view of the polishing apparatus 102 and polishing pad 101 according to the first embodiment. Note that the dimensions of each part in each figure are exaggerated for illustrative purposes. The holding platen 105 comprises first to sixth airbags A1 to A6 arranged concentrically on the lower surface of the top ring 105a, and a retainer ring 107 surrounding these first to sixth airbags A1 to A6. The retainer ring 107 is mounted on the top ring 105a and protrudes downward from the airbags A so as to surround the workpiece 103 when polishing it. The cross-sections of the first to sixth airbags A1 to A6 are each substantially rectangular, and the flat lower surfaces are processed to allow them to adhere closely to and hold the surface of the workpiece 103. As shown in Figure 8, the first to sixth airbags A1 to A6 are arranged concentrically, consisting of a circular first airbag A1 located in the center and ring-shaped second to sixth airbags A2 to A6 surrounding the first airbag A1. Each airbag A is capable of applying different pressures (P1 to P6) to the workpiece 103. The pressure applied to the first to sixth airbags A1 to A6 can be adjusted according to the workpiece 103 to be polished and various polishing conditions. Since such a holding platen 105 is known from Patent Document 1, further detailed explanation will be omitted.

[0031] The polishing pad 101 comprises a polishing layer 111 having a polishing surface that contacts the workpiece 103, a base layer 112 provided on the side of the polishing layer 111 opposite to the polishing surface and held by the polishing platen 104, and an adhesive layer (not shown) that bonds the polishing layer 111 and the base layer 112. The polishing layer 111 can be made of a polyurethane sheet, and such a polyurethane sheet can be made by mixing an isocyanate-terminated prepolymer (hereinafter sometimes simply referred to as a prepolymer), a curing agent, and a hollow body to form a polyurethane resin molded body, and then slicing the polyurethane resin molded body, and having countless voids formed inside. Here, the polyurethane sheet refers to a polyurethane resin containing polyurethane and polyurethane polyurea. The base layer 112 can be made of a urethane sponge, and such a urethane sponge can be a commercially available polyurethane sponge. Alternatively, the same polyurethane sheet as the polishing layer 111 may be used as the base layer 112. The adhesive layer consists of a pressure-sensitive adhesive, such as an acrylic adhesive, formed on the front and back surfaces of a core material made of polyethylene terephthalate (PET). There are no particular restrictions on the adhesive layer, and any double-sided tape known in the art can be arbitrarily selected and used.

[0032] The polyurethane sheet used for the abrasive layer 111 has a thickness of 0.5 to 2 mm, a Shore D hardness of 20.0 to 70.0, preferably 35.0 to 65.0, and a density of 0.60 to 1.10 g / cm³. ３ These can be set accordingly. By setting the Shore D hardness of the abrasive layer 111 within the above range, the occurrence of scratches can be suppressed. The urethane sponge used for the base layer 112 has a thickness of 0.5 to 2 mm, a Shore A hardness of 20.0 to 75.0, preferably 45.0 to 65.0, and a density of 0.2 to 0.7 g / cm³. ３These can be set accordingly. By setting the Shore A hardness of the base layer 112 within the above range, the cushioning of the polishing pad is improved, and the polishing rate can be improved. The storage modulus (40°C) of the polishing layer 111 is 55 to 400 MPa, preferably 70 to 130 MPa, and the storage modulus (40°C) of the base layer 112 is 1 to 10 MPa, preferably 2 to 8 MPa. It is desirable that the ratio of the storage modulus of the polishing layer 111 to the storage modulus of the base layer 112 be in the range of 2 to 60, preferably 5 to 50. By setting it in this way, it becomes possible to polish the workpiece without damaging the edge shape of the workpiece.

[0033] Figure 9 shows a view (hereinafter referred to as a plan view) of the area near the center of the concentric circular groove 113 on the polishing layer side of the polishing pad 101, as seen from the polishing surface side. The polishing surface of the polishing layer 111 has a polishing layer side concentric circular groove 113 formed by a plurality of concentric circular grooves 113a, and the adhesive surface of the base layer 112 on the polishing layer 111 side has a base layer side concentric circular groove 114 formed by a plurality of concentric circular grooves 114a, and the centers of these polishing layer side concentric circular grooves 113 and the centers of the base layer side concentric circular grooves 114 are spaced apart. Note that in Figure 9, the pitch of each concentric circular groove is shown with some spacing for illustrative purposes. In this embodiment, the center of the polishing layer side concentric circular groove 113 is set at a position 11 mm radially from the center of the polishing pad 101, and there are no limitations on the groove pitch or cross-sectional shape of adjacent circular grooves 113a, but the groove pitch is preferably 1.0 to 3.5 mm, and more preferably 1.2 to 3.0 mm. Here, the groove pitch of the circular grooves 113a is 1.7 mm, and the cross-section of each groove is approximately rectangular. On the other hand, the center of the concentric circular groove 114 on the base layer side is separated from the center of the concentric circular groove 113 on the polishing layer side by a required central distance, and there are no limitations on the groove pitch or cross-sectional shape of adjacent circular grooves 114a, but the groove pitch is preferably 1.0 to 3.5 mm, and more preferably 1.2 to 3.0 mm. Here, the groove pitch is the same as that of the concentric circular groove 113 on the polishing layer side, and the cross-section of each groove is approximately rectangular. Here, forming the concentric circular grooves 113 on the polishing surface of the polishing pad 101 is conventionally known, and by retaining the slurry inside when polishing the workpiece 103, it has the effect of improving polishing performance. In addition to the concentric grooves 113 on the polishing layer side, discharge grooves may be formed radially from the center of the polishing pad 101. By forming such discharge grooves, polishing debris and other materials generated during polishing can be discharged to the outside of the polishing pad 101 together with the slurry.

[0034] As shown in FIG. 9, by separating the center of the concentric circular groove 114 on the base material layer side from the center of the concentric circular groove 113 on the polishing layer side, when the polishing pad 101 is viewed in plan view, a plurality of intersection points Pc where the circular groove 113a constituting the concentric circular groove 113 on the polishing layer side intersects the concentric circular groove 114 on the base material layer side are formed. FIG. 10 is a diagram clearly showing the intersection point Pc between the concentric circular groove 113 on the polishing layer side and the concentric circular groove 114 on the base material layer side. For the sake of explanation, the circular groove 114a constituting the concentric circular groove 114 on the base material layer side is extended to the outside of the formed range of the polishing pad 101 and shown. For example, a total of four intersection points Pc are formed between the circular groove 113a located at the most central side in the concentric circular groove 113 on the polishing layer side and the plurality of circular grooves 114a constituting the concentric circular groove 114 on the base material layer side. On the other hand, 18 intersection points Pc are formed between each of the nine circular grooves 113a including the circular groove 113a located at the outermost side in the concentric circular groove 113 on the polishing layer side and the concentric circular groove 114 on the base material layer side. Among the circular grooves 113a constituting such a concentric circular groove 113 on the polishing layer side, the number of intersection points Pc formed in the circular groove 113a having the largest number of intersection points Pc is called the maximum number of intersection points, and this maximum number of intersection points is obtained by the circular groove 113a located on the outermost periphery of the concentric circular groove 113 on the polishing layer side.

[0035] The following formula 1 is the calculation formula for the maximum number of intersection points MAXPc. Here, MAXPc represents the maximum number of intersections, dc is the center distance between the concentric grooves 113 on the polishing layer side and the concentric grooves 114 on the base layer side, r is the radius of the outermost circular groove 113a among the concentric grooves 113 on the polishing layer side that are not connected to the outer circumference of the polishing pad 101 (hereinafter referred to as the maximum circular groove radius), and dsp is the groove pitch of the concentric grooves 114 on the base layer side. The first equation in Equation 1 is valid when the center distance dc is smaller than the maximum circular groove radius r, and the ratio of the groove pitch dsp of the concentric grooves 114 on the base layer side to the center distance dc is an integer. The second equation is valid when the center distance dc is smaller than the maximum circular groove radius r, and the ratio of the groove pitch dsp to the center distance dc is not an integer (it is a decimal multiple). The fourth equation is valid when the center distance dc is equal to the maximum circular groove radius r. The third equation holds when the central distance dc is greater than the maximum circular groove radius r. Finally, the fifth equation holds when the center point of the concentric groove 113 on the polishing layer side coincides with the center point of the concentric groove 114 on the base layer side.

[0036] Figure 11 shows a graph relating to the maximum number of intersections MAXPc according to equation 1. The horizontal axis represents the value of dc / dsp, and the vertical axis represents the maximum number of intersections MAXPc. Here, the maximum circular groove radius r is set to 1, and the groove pitch dsp of the concentric circular grooves 114 on the base layer side is set to 0.1. In this graph, when the first equation, i.e., dc / dsp is an integer, the value shifts vertically, and when the second equation, i.e., dc / dsp is not an integer, the graph shifts horizontally. Furthermore, when dc / dsp becomes 10, the center distance dc becomes equal to the maximum circular groove radius, so the fourth equation is applied. When dc / dsp becomes greater than 10, the center distance dc exceeds the maximum circular groove radius r, so the third equation is applied, and the maximum number of intersections MAXPc remains constant even if dc / dsp increases further. In Figure 9, the polishing pad 101 is designed so that when the maximum circular groove radius r is 1 and the pitch dsp of the concentric circular grooves 114 on the base material layer side is 0.1, dc / dsp is 4.4. As a result, according to the second equation, the maximum number of intersections MAXPc is 18.

[0037] Here, the verification of the maximum number of intersections MAXPc is performed using the number 1. Assuming a polishing pad 101 with a radius of 370 mm actually used, the maximum circular groove radius r of the concentric circular grooves 113 on the polishing layer side is set to a radius of 358.4 mm, and the groove pitches of the concentric circular grooves 113 on the polishing layer side and the concentric circular grooves 114 on the substrate layer side are each set to 1.7 mm. The lower limit of the maximum number of intersections MAXPc is the case where dc / dsp = 1. In other words, it is the case where the center distance dc is set to one pitch of the groove pitch dsp1 of the concentric circular grooves 114 on the substrate layer side. The maximum number of intersections MAXPc at this time is 4. On the other hand, the upper limit of the maximum number of intersections MAXPc is the case where dc / dsp = r / dsp = 210. That is, it is the case where the center distance dc is set to the maximum circular groove radius r. The maximum number of intersections MAXPc at this time is 842. However, although it is desirable that the maximum number of intersections MAXPc is large, increasing the maximum number of intersections MAXPc increases the center distance, so it becomes necessary to form a large number of circular grooves 114a of the concentric circular grooves 114 on the substrate layer side, resulting in a problem that the yield in manufacturing the substrate layer 112 deteriorates. Considering the yield, for example, it is conceivable to set the center distance dc to half of the maximum circular groove radius r. At this time, dc / dsp = (r / 2) / dsp = 105, and the maximum number of intersections MAXPc is 422. Thus, when considering both the yield while taking into account the suppression effect of Wavy, it is desirable that the maximum number of intersections MAXPc is between 16 and 422, and more desirably between 18 and 46.

[0038] Figure 16 is a plan view of the polishing pad according to the second embodiment. Compared to the first embodiment shown in Figure 9, the circular groove 114a of the concentric groove 114 on the base layer side formed on the adhesive surface of the base layer 112 is provided so as not to reach the outer circumference of the base layer 112, and the circular groove 114a is positioned so as to form a flat portion at the center of the base layer 112. The concentric groove 113 on the polishing layer side in this embodiment is provided at a required central distance from the center of the polishing pad 101, and the same settings as in the first embodiment can be used for the cross-sectional shape, depth, width, and groove pitch of the circular groove 113a. On the other hand, the concentric groove 114 on the base layer side is formed between a circular boundary line A shown by a dashed line set on the center side of the polishing layer 3 and a circular boundary line A shown by a dashed line set on the outer edge side of the polishing layer 3. The center of the boundary line A is set to the center of the polishing pad 101, and the region formed between them corresponds to the range of movement of the workpiece 103 and the retainer ring 107, which move relative to the polishing pad 101 during polishing. In this embodiment, the center of the concentric groove 114 on the base layer side coincides with the center of the polishing pad 101, and the cross-sectional shape, depth, width, and groove pitch of the other circular grooves 114a can be set to the same settings as in the first embodiment. Note that the center of the circular groove 114a of the concentric groove 114 on the base layer side may be set away from the center of the polishing pad 101, but in this case the circular groove 114a will be divided at the position where it intersects with the boundary line A, so processing to form the end of the circular groove 114a will be necessary.

[0039] In this way, by positioning the circular grooves 114a of the base layer side concentric grooves 114 so as not to reach the outer edge of the base layer 112, a hole is not formed on the side surface of the polishing pad 101 by the concentric grooves 114 on the base layer side after the polishing layer 111 and the base layer 112 are bonded together by the adhesive layer. This prevents the slurry S that has flowed down the side surface of the polishing pad 101 from entering between the base layer 112 and the adhesive layer via the concentric grooves 114 on the base layer side when the workpiece 103 is polished by the polishing pad 101, thereby preventing the base layer 112 and the adhesive layer from peeling off during polishing. Furthermore, by positioning the circular grooves 114a so that a flat portion is formed in the center of the base layer 112, the circular grooves 114a do not come too close together in the center of the base layer 112, preventing the central part of the polishing pad 101 from being excessively deformed by the workpiece 103, and thus reducing waviness. Furthermore, by providing the concentric grooves 114 on the base layer side in areas corresponding to the movement range of the workpiece 103 and the retainer ring 107, the stress when the workpiece 103 is pressed against the polishing pad 101 is distributed, thereby reducing waviness.

[0040] Figure 17 shows a cross-sectional view of the polishing pad 101 according to the third embodiment. In the first and second embodiments, the base layer 112 was provided with the base layer-side concentric groove 114, whereas in the third embodiment, the adhesive surface of the polishing layer 111 on the base layer 112 side is formed with a base layer-side concentric groove 116, which is composed of a plurality of concentric circular grooves 116a. The base layer-side concentric groove 116 can be formed with the same configuration as the base layer-side concentric groove 114 in the first and second embodiments, so that when the polishing pad 101 is viewed in plan view, a plurality of intersection points Pc are formed in the circular groove 113a that constitutes the polishing layer-side concentric groove 113, intersecting with the circular groove 116a of the base layer-side concentric groove 116. Furthermore, in this embodiment, since a concentric groove 113 on the polishing layer side and a concentric groove 116 on the base layer side are formed in the polishing layer 111, their depths can be set according to the thickness of the polishing layer 111. As for the circular grooves 116a of the concentric grooves 116 on the base layer side, as in the second embodiment, each circular groove 116a may be provided so as not to reach the outer edge of the polishing layer 111.

[0041] Furthermore, Figure 18 shows a cross-sectional view of the polishing pad 101 according to the fourth embodiment. In this embodiment, compared to the first embodiment shown in Figure 7, a base layer-side concentric groove 117, composed of a plurality of concentric circular grooves 117a, is provided on the holding surface of the base layer 112 on the polishing platen 104 side. The base layer-side concentric groove 117 can be formed with the same configuration as the base layer-side concentric groove in each of the above embodiments, so that when the polishing pad 101 is viewed in plan view, a plurality of intersection points Pc are formed in the circular groove 113a that constitutes the polishing layer-side concentric groove 113, intersecting with the circular groove 117a of the base layer-side concentric groove 117. The circular grooves 117a of the base layer-side concentric groove 117 may be provided so that each circular groove 117a does not reach the outer edge of the polishing layer 111, as in the second embodiment.

[0042] The following describes a method for manufacturing a polishing pad 101 comprising the polishing layer 111 and the base layer 112. Here, we will describe a method for manufacturing a polishing pad 101 according to the first embodiment. The polyurethane sheet constituting the polishing layer 111 is manufactured by a prepolymer method in which a polyurethane composition is obtained by adding and mixing an isocyanate-terminated prepolymer, which is a reaction intermediate between a polyol component and an isocyanate component, with a curing agent (chain extender) such as diamines or diols, a foaming agent, a catalyst, etc., and curing the resulting polyurethane composition. The prepolymer method includes, for example, a preparation step of preparing a urethane bond-containing isocyanate compound as an isocyanate-terminated prepolymer, a curing agent, and a hollow body; a mixing step of mixing the urethane bond-containing isocyanate compound and the curing agent to obtain a mixed liquid for molding a molded body; and a molded body molding step of molding a polyurethane polyurea resin molded body from the mixed liquid for molding a molded body. As a method for manufacturing the urethane sponge constituting the base layer 112, for example, a method of curing a composition containing a resin prepolymer, a curing agent, and a foaming agent by heating the composition, thereby foaming the composition. As the prepolymer and curing agent used in the manufacture of the sponge, those exemplified in the method for manufacturing the polishing layer can be used. Then, a polishing layer forming step is performed in which the polyurethane polyurea resin molded body obtained by such a prepolymer method is sliced ​​to a predetermined thickness to obtain a polishing layer 111; a base layer forming step is performed in which the urethane sponge is sliced ​​to a predetermined thickness to obtain a base layer 112; a groove forming step is performed in which the concentric grooves are formed in the polishing layer 111 and the base layer 112; and a cutting step is performed in which the polishing layer 111 and the base layer 112 are bonded together and then cut into a circular shape, thereby obtaining the disc-shaped polishing pad 101 according to this embodiment.

[0043] In the preparation step for manufacturing the polishing layer 111, at least a urethane bond-containing isocyanate compound, a curing agent, and a hollow body are used as raw materials for the polyurethane resin molded article. A polyol compound may also be used together with the above components, and other components may be used in combination as long as they do not impair the effects of the present invention. The urethane bond-containing isocyanate compound prepared in this preparation step is a compound obtained by reacting the following polyisocyanate compound and polyol compound under commonly used conditions, and contains a urethane bond and an isocyanate group in its molecule. In addition, other components may be included in the urethane bond-containing isocyanate compound as long as they do not impair the effects of the present invention. As the urethane bond-containing isocyanate compound, a commercially available one may be used, or one synthesized by reacting a polyisocyanate compound and a polyol compound may be used. There are no particular restrictions on the reaction, and an addition polymerization reaction may be carried out using methods and conditions known in the production of polyurethane resins. For example, it can be manufactured by adding a polyisocyanate compound heated to 50°C to a polyol compound heated to 40°C while stirring under a nitrogen atmosphere, raising the temperature to 80°C after 30 minutes, and then reacting at 80°C for another 60 minutes.

[0044] First, the term "polyisocyanate compound" refers to a compound having two or more isocyanate groups in its molecule. Furthermore, there are no particular limitations on what constitutes a polyisocyanate compound, as long as it has two or more isocyanate groups in its molecule. For example, diisocyanate compounds having two isocyanate groups in their molecule include m-phenylenediisocyanate, p-phenylenediisocyanate, 2,6-tolylenediisocyanate (2,6-TDI), 2,4-tolylenediisocyanate (2,4-TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), 3,3'-dimethoxy-4,4'-biphenyldiisocyanate, and 3,3'-dimeth Examples of polyisocyanate compounds include diphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate, and ethyridine diisothiocyanate. Furthermore, diisocyanate compounds are preferred as polyisocyanate compounds, with 2,4-TDI, 2,6-TDI, MDI, and hydrogenated MDI being more preferred, and particularly preferred to contain 2,4-TDI and / or 2,6-TDI. These polyisocyanate compounds may be used individually or in combination of multiple polyisocyanate compounds.

[0045] Next, the polyol compound refers to a compound having two or more alcoholic hydroxyl groups (OH) in its molecule. Examples of polyol compounds used in the synthesis of the urethane bond-containing isocyanate compound include diol compounds such as ethylene glycol, diethylene glycol (DEG), and butylene glycol, triol compounds, etc.; polyether polyol compounds such as poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) (PTMG), polyethylene glycol (PEG), and polypropylene glycol (PPG); polyester polyol compounds such as reaction products of ethylene glycol and adipic acid or reaction products of butylene glycol and adipic acid; polycarbonate polyol compounds, polycaprolactone polyol compounds, etc., and combinations thereof. In addition, trifunctional propylene glycol to which ethylene oxide has been added can also be used. Among these, combinations of polyester polyols such as PTMG and DEG, PPG and DEG, or reaction products of butylene glycol and adipic acid with DEG are preferred. The polyol compound may be used alone, or multiple polyol compounds may be used in combination.

[0046] Here, the NCO equivalent of the isocyanate-terminated prepolymer, which represents the molecular weight of PP (isocyanate-terminated prepolymer) per NCO group, is preferably 200 to 800, more preferably 300 to 700, and even more preferably 400 to 600. Specifically, the NCO equivalent of the isocyanate-terminated prepolymer can be determined as follows: NCO equivalent of isocyanate-terminated prepolymer = (parts by mass of polyisocyanate compound + parts by mass of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound × parts by mass of polyisocyanate compound / molecular weight of polyisocyanate compound) - (number of functional groups per molecule of polyol compound × parts by mass of polyol compound / molecular weight of polyol compound)]

[0047] As the curing agent (also called a chain extender), for example, a polyamine compound and / or a polyol compound can be used. A polyamine compound means a compound having two or more amino groups in its molecule, and aliphatic or aromatic polyamine compounds, especially diamine compounds, can be used. For example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA), and polyamine compounds having a structure similar to MOCA can be mentioned. Furthermore, the polyamine compound may also have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. As the polyamine compound, diamine compounds are preferred, more preferably MOCA, diaminodiphenylmethane, and diaminodiphenylsulfone, with MOCA being particularly preferred. The polyamine compound may be used alone or in combination of multiple polyamine compounds. To facilitate mixing with other components and / or to improve the uniformity of the bubble diameter in the subsequent molded article formation process, it is preferable to degas the polyamine compound under reduced pressure while heated as necessary. As a method for degassing under reduced pressure, any method known in the production of polyurethane may be used, for example, degassing can be performed using a vacuum pump at a vacuum of 0.1 MPa or less. When a solid compound is used as the curing agent (chain extender), it can be degassed under reduced pressure while being melted by heating.

[0048] Furthermore, any polyol compound such as diol compounds or triol compounds can be used as a curing agent without particular restrictions. It may also be the same as or different from the polyol compound used to form the isocyanate-terminated prepolymer. Specific examples include low molecular weight diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, and high molecular weight polyol compounds such as poly(oxytetramethylene) glycol, polyethylene glycol, and polypropylene glycol. The polyol compounds may be used individually or in combination of multiple polyol compounds.

[0049] Here, the components are mixed so that the R value, which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the isocyanate groups present at the ends of the urethane bond-containing isocyanate compound, is 0.60 to 1.40. The R value is preferably 0.65 to 1.30, and more preferably 0.70 to 1.20.

[0050] The term "hollow body" refers to a microsphere having voids. Microspheres include spherical, elliptical, and nearly spherical shapes. Examples of hollow bodies include unexpanded, heat-expandable microspheres consisting of an outer shell (polymer shell) made of a thermoplastic resin and a low-boiling-point hydrocarbon enclosed within the outer shell, or unexpanded, heat-expandable microspheres that have been heated and expanded. As the polymer shell, thermoplastic resins such as acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methyl methacrylate copolymer, and vinyl chloride-ethylene copolymer can be used, as disclosed in Japanese Patent Publication No. 57-137323, etc. Similarly, as the low-boiling-point hydrocarbon enclosed within the polymer shell, examples such as isobutane, pentane, isopentane, and petroleum ether can be used.

[0051] Next, the mixing process will be described. In this mixing process, the urethane bond-containing isocyanate compound as an isocyanate-terminated prepolymer, the curing agent, and the hollow body, which were prepared in the preparation process, are supplied to the mixer and stirred and mixed. The mixing process is carried out under conditions where the mixture is heated to a temperature that ensures the fluidity of each component. There are no particular restrictions on the mixing order, but it is preferable to prepare a mixture of the urethane bond-containing isocyanate compound and the hollow body, and a mixture of the curing agent and other components as needed, and to supply both mixtures to the mixer and stir them together. In this way, a mixture for molding a molded article is prepared.

[0052] Next, in the molding process, the mixed liquid for molding the molded body prepared in the mixing process is poured into a mold at 50 to 130°C and cured to form a polyurethane resin molded body. At this time, the mixed liquid hardens as the isocyanate-terminated prepolymer and curing agent react to form polyurethane resin.

[0053] The sponge used in the base layer 112 may be manufactured by known methods or obtained commercially. Polyurethane foam manufactured by Inoac Corporation, polyurethane foam manufactured by Sekisui Chemical Co., Ltd., or polyurethane foam manufactured by NHK Spring Co., Ltd. may be used.

[0054] Next, in the polishing layer formation step, the polyurethane resin molded body obtained is sliced ​​into a sheet of the required thickness to obtain the polishing layer 111. Similarly, in the base layer formation step, the urethane sponge obtained is sliced ​​into a sheet of the required thickness to obtain the base layer 112. The polishing layer 111 and base layer 112 obtained in this way are rectangular sheets, and in the groove formation step, concentric grooves 113 on the polishing layer side and concentric grooves 114 on the base layer side are formed on the surface of the sheet-shaped polishing layer 111 corresponding to the polishing surface and on the surface of the base layer 112 corresponding to the adhesive surface. Next, the polishing layer 111 and the base layer 112 with concentric grooves are bonded together using double-sided tape or the like that which constitutes the adhesive layer, and at this time, as described above, the center of the concentric groove 113 on the polishing layer side and the center of the concentric groove 114 on the base layer side are bonded together by a predetermined central distance. Subsequently, for example, by using the center of the concentric groove 113 on the polishing layer side of the polishing layer 111 as a reference, the bonded polishing layer 111 and the base layer 112 are cut in a circular shape to obtain a disc-shaped polishing pad 101.

[0055] Figure 12 shows the results of measuring the amount of wavy in the response area of ​​each airbag using the polishing pads 101 of Examples 1 to 3 of the present invention and the polishing pads 101 of Comparative Examples 1 and 2 as comparative examples. The pressure response area on the horizontal axis refers to the range over which the pressure applied to the workpiece 103 by the first to sixth airbags A1 to A6, corresponding to Figure 8, is transmitted. Here, the ranges are from the center of the workpiece 103 outward in the radial direction: Airbag A1: 0-30 mm, A2: 15-65 mm, A3: 45-87 mm, A4: 70-112 mm, A5: 95-130 mm, A6: 115-140 mm. The reason why the pressure response areas of each airbag A1 to A6 overlap is that each airbag A1 to A6 exerts a certain degree of stress on the workpiece 103. The vertical axis represents the amount of wavy in the airbag response area. The amount of wavy is the difference between the maximum and minimum polishing rates, and this difference is calculated within the range of the airbag response area.

[0056] Figure 13 is a graph showing the surface condition of a workpiece 103 polished using the polishing pads 101 according to Examples 1-3 and Comparative Examples 1 and 2. The horizontal axis of the graph shows the distance from the center of the workpiece 103 toward the outer circumference in the radial direction, and the vertical axis shows the polishing rate at a position corresponding to the distance from the center of the workpiece 103. In other words, the vertical axis shows the surface condition of the workpiece. For convenience, Comparative Examples 1, 2, and Examples 1-3 are shown side by side to make it easier to compare the surface conditions of the workpieces.

[0057] Example 1 The polishing pad 101 of Example 1 has a diameter of 740 mm, and the polishing layer 111 has a density of 0.88 g / cm³. ３A polyurethane sheet with a D hardness of 44.0 and a thickness of 1.6 mm was used for the polishing layer 111. A urethane sponge with a thickness of 1.0 mm and a Shore A hardness of 71 was used for the base layer 112, and double-sided tape with a PET core material with a thickness of 0.05 mm was used for the adhesive layer. The storage modulus of the polishing layer 111 (at 40°C) was 98.2 MPa, while the storage modulus of the base layer 112 (at 40°C) was 7.2 MPa. As a result, the ratio of the storage modulus of the polishing layer 111 to that of the base layer 112 was 13.6. The concentric circular grooves 113 formed on the entire polishing surface side of the polishing layer 111 were positioned at a distance of 11 mm from the center of the polishing pad 101, with a groove pitch of 1.7 mm, a width of 0.4 mm, and a depth of 0.8 mm. The maximum circular groove radius r at this time was 358.4 mm. Furthermore, the concentric circular grooves 114 on the substrate layer side, formed on the entire adhesive surface side of the substrate layer 112, have a center distance dc of 7.5 mm from the center of the concentric circular grooves 113 on the polishing layer side, and the groove pitch dsp is set to 1.7 mm, width to 0.4 mm, and depth to 0.5 mm. According to the above formula 2, dc / dsp = 4.4, and by applying the second formula, the maximum number of intersections MAXPc is 18.

[0058] Example 2 The polishing pad 101 of Example 2 uses a polishing layer 111 and a base layer 112 having the same hardness as the polishing pad 101 of Example 1, and also uses the same adhesive layer. On the polishing surface of the polishing layer 111, concentric circular grooves 113 are formed on the polishing layer side in the same arrangement as in Example 1, while concentric circular grooves 116 are formed on the entire adhesive surface side of the polishing layer 111 as in the third embodiment. The circular grooves 116a of the concentric circular grooves 116 on the base layer side are arranged in the same way as the circular grooves 114a of Example 1. In Example 2 as well, according to Equation 2, dc / dsp = 4.4, and by applying the second equation, the maximum number of intersections MAXPc is 18.

[0059] Example 3 The polishing pad 101 of Example 3 uses a polishing layer 111 and a base layer 112 having the same hardness as the polishing pad 101 of Example 1, and also uses the same adhesive layer. The concentric circular grooves 113 formed on the polishing surface of the polishing layer 111 are positioned at a distance of 11 mm from the center of the polishing pad 101, with a groove pitch of 1.7 mm, a width of 0.4 mm, and a depth of 0.8 mm. The maximum circular groove radius r at this time was 358.4 mm. In addition, a concentric circular groove 116 is formed on the adhesive surface of the polishing layer 111, as in Example 2, and the center of the concentric circular groove 116 is set to the center of the polishing pad 101, so that the circular groove 116a does not reach the outer edge of the polishing layer 3, as in the third embodiment. Specifically, the center of the concentric groove 116 on the base layer side was aligned with the center of the polishing pad 101, and the radius of the innermost circular groove 116a was set to 55 mm, and the radius of the outermost circular groove 116a was set to 335 mm. Within the range of the aforementioned area, the groove pitch dsp was set to 1.7 mm, the width to 0.4 mm, and the depth to 0.5 mm. According to the above formula 2, dc / dsp = 4.4, and by applying the second formula, the maximum number of intersections MAXPc is 18.

[0060] Comparative Example 1 In comparison to the above example, the polishing pad 101 used as a comparative example had the same hardness and other properties as the polishing pad 101 of Example 1, and the same adhesive layer was used. On the polishing surface of the polishing layer 111 of Comparative Example 1, concentric grooves 113 were formed on the polishing layer side in the same arrangement as in Example 1, while concentric grooves 114 were not formed on the base layer side.

[0061] Comparative Example 2 In contrast to the above example, the comparative example polishing pad 101 used an abrasive layer 111 and a base layer 112 having the same hardness as the polishing pad 101 of Example 1, and also used the same adhesive layer. On the polishing surface of the polishing layer 111 of Comparative Example 2, concentric circular grooves 113 on the polishing layer side were formed in the same arrangement as in Example 1, while the concentric circular grooves 114 on the base layer side were formed with their centers aligned with the concentric circular grooves 113 on the polishing layer side and with the same groove pitch as the concentric circular grooves 113 on the polishing layer side. However, the concentric circular grooves 114 on the base layer side were offset by half a pitch from the concentric circular grooves 113 on the polishing layer side, so that the circular grooves 114a of the concentric circular grooves 114 on the base layer side were positioned between the circular grooves 113a that constitute the concentric circular grooves 113 on the polishing layer side, so that the concentric circular grooves 113 on the polishing layer side and the concentric circular grooves 114 on the base layer side did not intersect.

[0062] Next, the polished layers 111 of Examples 1 to 3 and Comparative Examples 1 and 2 were obtained as follows: A first isocyanate-terminated urethane prepolymer with an NCO equivalent of 560 was prepared by reacting 2,4-tolylene diisocyanate (TDI), polypropylene glycol (PPG) with a number average molecular weight of 1000, and diethylene glycol (DEG). A second isocyanate-terminated urethane prepolymer with an NCO equivalent of 600 was prepared by reacting 2,4-tolylene diisocyanate (TDI), a polyester polyol with a number average molecular weight of 2000 obtained by reacting adipic acid and 1,4-butanediol, and diethylene glycol (DEG). Subsequently, the prepared first and second isocyanate-terminated urethane prepolymers were mixed in a weight ratio of 50:50 to prepare a mixed isocyanate-terminated urethane prepolymer with an NCO equivalent of 580. Furthermore, 3.5 parts of unexpanded microspheres with an average particle size of 8.5 μm, in which the outer shell consists of an acrylonitrile-vinylidene chloride copolymer and isobutane gas is contained within the shell, were added and mixed to 100 parts of the prepared mixed isocyanate-terminated urethane prepolymer to obtain a urethane prepolymer mixture. The obtained urethane prepolymer mixture was placed in the first liquid tank and kept warm at 80°C. Separately from the first liquid tank, 20.9 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (MOCA) as a curing agent were placed in the second liquid tank, heated and melted at 120°C, and mixed to obtain a curing agent molten solution. Next, the liquids from the first and second liquid tanks were injected through the respective inlets of a mixer equipped with two inlets, and stirred to obtain a mixed solution. At this time, the mixing ratio was adjusted so that the R value, which represents the equivalent ratio of amino groups and hydroxyl groups present in the curing agent to the isocyanate groups present at the ends of the urethane prepolymer, was 0.90. The resulting mixture was poured into a mold preheated to 80°C and primary cured at 80°C for 30 minutes. The formed block-shaped molded product was removed from the mold and secondary cured in an oven at 120°C for 4 hours to obtain a polyurethane resin molded product. After the obtained polyurethane resin molded product was allowed to cool to 25°C, it was heated again in an oven at 120°C for 5 hours, and then sliced ​​to a thickness of 1.6 mm to obtain a polished layer 111.

[0063] On the other hand, the base layer 112 of the above-mentioned examples and comparative examples was obtained by purchasing polyurethane foam from Sekisui Chemical Co., Ltd. and buffing it to a thickness of 1.0 mm to obtain the support layer 12.

[0064] The density of the polished layer 111 in the above examples and comparative examples (g / cm³) ３The Shore D hardness of the abrasive layer 111, made of polyurethane sheet, was measured in accordance with the Japanese Industrial Standard (JIS-K-6505). The Shore D hardness of the abrasive layer 111, made of polyurethane sheet, was measured using a D-type hardness tester in accordance with the Japanese Industrial Standard (JIS-K-6253). Here, the measurement sample was obtained by stacking multiple abrasive layers 111 as needed, so that the total thickness was at least 4.5 mm. On the other hand, the Shore A hardness of the base layer 112, made of urethane sponge, was measured using an A-type hardness tester in accordance with the Japanese Industrial Standard (JIS-K-7311). Here, the measurement sample was obtained by stacking multiple base layer 112 as needed, so that the total thickness was at least 4.5 mm. (Dynamic Viscoelasticity Test) Dynamic viscoelasticity tests were performed on the abrasive layer 111 and base layer 112 based on the following measurement conditions. The polished layer 111 and base layer 112, kept in a constant temperature and humidity chamber at a temperature of 23°C (±2°C) and relative humidity of 50% (±5%) for 40 hours, were used as samples. The polished layer was measured in tensile mode and the base layer in compression mode under normal atmospheric conditions (dry state). (Measurement conditions: polished layer) Measurement device: RSA-G2 (TA Instruments Co., Ltd.) Sample size (polished layer): 5 cm (length) x 0.5 cm (width) x 0.16 cm (thickness) Test length: 1 cm Test mode: tensile mode Frequency: 10 rad / s (1.6 Hz) Measurement temperature: 20-100°C Heating rate: 5°C / min Strain range: 0.10% Initial load: 148 g Measurement interval: 2 points / °C (Measurement conditions: substrate layer) Measurement device: RSA-G2 (TA Instruments Co., Ltd.) Frequency: 1 Hz Sample size (substrate layer): 1 cm (length) x 1 cm (width) x 0.1 cm (thickness) Test mode: compression Measurement temperature: 20-100°C Heating rate: 3°C / min Strain range: 0.10% Initial load: 100 g

[0065] Experiments were conducted on the polishing pads 101 of the above-mentioned examples and comparative examples obtained in this manner, based on the following polishing conditions, to determine whether or not wavy material was formed on the polished surface of the workpiece 103. In this experiment, the Cu film substrate was polished under the following polishing conditions, and the polished surface of the workpiece 103 was measured when the predetermined polishing was completed. (Polishing conditions) Polishing machine: F-REX300X (manufactured by Ebara Corporation) Disk: 34J (manufactured by KINIK Corporation) Rotation speed: (Holding platen) 90 rpm, (Polishing platen) 81 rpm Polishing pressure: 2.7 psi Polishing agent temperature: 20℃ Polishing agent discharge rate: 350 ml / min Polishing agent: CSL-9044C (CSL-9044C concentrate: pure water = weight ratio 1:9 mixture used) (manufactured by Fujifilm Planar Solutions Co., Ltd.) Workpiece 103 (metal film): Cu film substrate (disc shape with a diameter of 300 mm) Polishing time: 60 seconds Pad break: 20N 60 minutes Conditioning: In-situ, 20N

[0066] The presence or absence of wavy was evaluated as follows. In the graph in Figure 12, Comparative Examples 1 and 2 show large variations in the amount of wavy in the response areas of each airbag A1 to A6, and exhibit an overall undulating tendency, indicating that wavy is present. In contrast, Examples 1 to 3 show a relatively constant amount of wavy in each airbag, and in particular, Examples 1 and 2 have a wavy amount within 180 Å, and do not show an overall undulating tendency, confirming that wavy has been reduced.

[0067] Furthermore, in the graph of Figure 13, the boundary positions between the airbag A and the airbag A provided on the holding platen 105 correspond to positions of 20 mm, 50 mm, 75 mm, 100 mm, 120 mm, and 130 mm relative to the center of the workpiece 103 under the polishing conditions. When polishing was performed with the polishing pads 101 of Examples 1 to 3, it was confirmed that the irregularities generated at the boundary positions of the airbag A were smaller than when polishing was performed with the polishing pads 101 of Comparative Examples 1 and 2, confirming that the waviness was reduced.

[0068] The experimental results will be discussed below using Figures 14 and 15. Figure 14 shows the case using the polishing pad 101 of the first embodiment, and Figure 15 shows the case using the polishing pad 101 of Comparative Example 2. It is also considered that the same phenomenon will occur with the polishing pad 101 having the characteristics of the second and third embodiments and the embodiment 3. First, considering the mechanism of wave formation, when polishing the workpiece 103 with the polishing pad 101, the amount of polishing of the workpiece 103 is affected by various polishing conditions, but it is known that as a general trend, it can be expressed by the following Preston equation: (Equation 2) RR = kPv In Equation 2 above, RR is the amount of polishing, k is a proportionality constant determined by the polishing conditions, P is the polishing pressure when pressing the workpiece 103 against the polishing pad 101, and v is the polishing speed between the workpiece 103 and the polishing pad 101. According to equation 2, it can be understood that the amount of polishing is proportional to the polishing pressure. Therefore, in order to improve the throughput of the polishing process for the workpiece 103, the workpiece 103 is pressed against the polishing pad 101 with a large pressing force using the holding platen 105.

[0069] On the other hand, in order to uniformly polish the workpiece 103 while pressing it with a large pressing force, as in this embodiment, concentric airbags A are provided on the holding platen 105 to apply different pressures radially to the workpiece 103. However, when using a holding platen 105 equipped with multiple airbags A, at the boundary position B between adjacent airbags A, the pressure from each airbag A is not transmitted to the workpiece 103, and the pressing force at that position is lower than at other parts. As a result, the rebound force from the polishing pad 101 due to compression is concentrated in the part of the workpiece 103 corresponding to the boundary position B between airbags A, and this part is excessively polished, so that concentric irregularities are formed in line with the boundary position B, resulting in the wavy appearance.

[0070] Figures 14 and 15 show the state in which the workpiece 103 is fixed and the polishing pad 101 is rotating relative to it. When using the polishing pad 101 according to this embodiment shown in Figure 14, the cross-sectional shape of the polishing pad 101 in contact with the same position on the workpiece 103 changes moment by moment as shown in Figures 14(a), (b), and (c). The polishing pad 101 in Figure 14 is formed such that the first equation in Equation 2, i.e., dc / dsp, is an integer, by forming concentric circular grooves 113 on the polishing layer side and concentric circular grooves 114 on the base layer side. As described above, when the polishing pad 101 of this embodiment is used, as the workpiece 103 and the polishing pad 101 rotate relative to each other, the portion of the workpiece 103 corresponding to the boundary position B will repeatedly come into contact with the following areas: a portion where neither the polishing layer side concentric groove 113 nor the base layer side concentric groove 114 is formed; a portion where the polishing layer side concentric groove 113 and the base layer side concentric groove 114 do not overlap (a); a portion where the polishing layer side concentric groove 113 and the base layer side concentric groove 114 partially overlap (b); and a portion where an intersection point Pc is formed where the polishing layer side concentric groove 113 and the base layer side concentric groove 114 intersect (c). As a result, the cross-sectional shape of the contacting polishing pad 101 will change moment by moment. The states shown in (a), (b), and (c) will occur repeatedly at short intervals as the number of maximum intersection points MAXPc increases.

[0071] Furthermore, the portion of the polishing layer 111 and the base layer 112 in which grooves are formed has a reduced repulsive force on the workpiece 103 compared to the portion without grooves. As a result, the cross-sectional shape of the polishing pad 101 changes moment by moment, as shown in Figure 14, thereby dispersing the repulsive force on the workpiece 103. Therefore, it is presumed that even at the position B corresponding to the boundary position B of the airbag A on the workpiece 103, different repulsive forces act from the polishing pad 101 in each of the states (a), (b), and (c), suppressing stress concentration and preventing the formation of wavy surfaces.

[0072] In contrast, the polishing pad 101 shown in Figure 15 does not have concentric grooves 113 on the polishing layer side and concentric grooves 114 on the base layer side intersecting, as in Comparative Example 2. Therefore, when viewed at the same position on the workpiece 103, the cross-sectional shape of the contacting polishing pad 101 does not change, as shown in Figures 15(a) and (b). Furthermore, even when the concentric grooves 114 on the base layer side are not formed, as in Comparative Example 1, the cross-sectional shape of the contacting polishing pad 101 does not change. For this reason, it is presumed that at the position corresponding to the boundary position B on the workpiece 103, the repulsive force from the polishing pad 101 becomes constant, stress concentrates and excessive polishing occurs, resulting in the generation of concentric waves along the boundary position B.

[0073] In addition, in the polishing pad 101 of each of the above embodiments, it is also possible to fill the concentric grooves 114, 116, and 117 on the base layer side with the required resin. As the resin, UV-curable resin, urethane resin, silicone resin, acrylic resin, rubber, etc. can be used. As the rubber, natural rubber, nitrile rubber, polyurethane rubber, etc. can be used. The materials may be used individually or in combination of multiple materials. By filling the concentric grooves 114, 116, and 117 on the base layer side with resin in this way, the repulsive force when the object to be polished 103 is pressed against the polishing pad 101 can be made different between the resin portion forming the base layer 112 and the polishing layer 111 and the portion where the resin-filled concentric grooves 114, 116, and 117 are formed on the base layer side, and the same effect as the polishing pad 101 of each of the above embodiments can be expected.

[0074] Furthermore, in each of the above embodiments, the concentric grooves 114, 116, and 117 on the base layer side are formed on the adhesive surface on the polishing layer side of the base layer 112 (first embodiment), the adhesive surface on the base layer side of the polishing layer 111 (third embodiment), and the holding surface on the polishing platen 104 side (fourth embodiment), respectively. However, it is also possible to form them on the adhesive surface of the polishing layer and the adhesive surface of the base layer, for example. Moreover, even if the polishing device 102 has a configuration in which a pressure adjustment means composed of a plurality of concentrically arranged pressing means is provided instead of the airbag A of the holding platen 105, wavy may occur at the boundary between each pressing means. Therefore, by using the polishing pad 101 according to the present invention, it is possible to suppress the occurrence of such wavy.

[0075] The fifth to eighth embodiments will be described below. Figure 19 shows a polishing apparatus 202 equipped with a polishing pad 201 according to the present invention, which is used to polish an object to be polished 203 such as a semiconductor substrate. The polishing apparatus 202 includes a polishing platen 204 provided below to support the polishing pad 201, a holding platen 205 provided above to support the object to be polished 203, and a slurry supply means 206 for supplying slurry S. The polishing pad 201 and the object to be polished 203 each have a substantially disc shape, and the polishing pad 201 is formed to have a larger diameter than the object to be polished 203. The polishing pad 201 is held on the upper surface of the polishing platen 204 by double-sided tape or the like, and the object to be polished 203 is held on the lower surface of the holding platen 205 via an airbag A, which will be described later. The rotation center of the holding platen 205 is positioned offset from the rotation center of the polishing platen 204. When the polishing platen 204 and the holding platen 205 are rotated by a driving means (not shown), the polishing pad 201 and the workpiece 203 slide relative to each other while rotating. The slurry supply means 206 supplies a slurry S, in which abrasive particles are mixed in a required liquid, to the polishing surface of the polishing pad 201. This allows the slurry S to penetrate between the polishing surface and the workpiece 203, thereby performing so-called chemical mechanical polishing (CMP).

[0076] Figure 20 shows a cross-sectional view of a polishing apparatus 202 according to the fifth embodiment. Note that the dimensions of each part in each figure are exaggerated for illustrative purposes. The holding platen 205 comprises a disc-shaped top ring 205a that rotates by the driving means, concentric first to sixth airbags A1 to A6 provided on the lower surface of the top ring 205a, and a retainer ring 207 provided so as to surround the first to sixth airbags A1 to A6. The rotation center of the holding platen 205 is set to the center of the first to sixth airbags A1 to A6, and each airbag A has a substantially rectangular cross-section, and the flat lower surface is processed to allow it to adhere closely to and hold the surface of the workpiece 203 to be polished. Each of the first to sixth airbags A1 to A6 can apply different pressures to the workpiece 203 to be polished, and the pressure applied by the first to sixth airbags A1 to A6 can be adjusted according to the workpiece 203 to be polished and various polishing conditions. Furthermore, since such a holding plate 205 is known from Patent Document 1, a further detailed explanation will be omitted.

[0077] The retainer ring 207 is provided to protrude below the lower surfaces of the first to sixth airbags A1 to A6, and when the workpiece 203 is held by the airbag A during polishing, the workpiece 203 is housed inside the retainer ring 207. As described above, when the polishing platen 204 and the holding platen 205 are rotated, the workpiece 203 moves in a trajectory that rotates on its own axis while revolving around the center of the polishing pad 201, as shown in Figure 21, and a ring-shaped range of movement M is formed on the polishing pad 201 by the workpiece 203 and the retainer ring 207. The range of movement M of the workpiece 203 and the retainer ring 207 does not extend beyond the outer edge of the polishing pad 201, and a portion of the central part of the polishing pad 201 does not come into contact with the workpiece 203 and the retainer ring 207.

[0078] The polishing pad 201 comprises a polishing layer 211 having a polishing surface 211a that contacts the workpiece 203, a base layer 212 provided on the side of the polishing layer 211 opposite to the polishing surface 211a, and an adhesive layer 213 that bonds the polishing layer 211 and the base layer 212. The polishing layer 211 is not particularly limited, but a polyurethane sheet can be used. As such a polyurethane sheet, a foamed polyurethane sheet can be used, which is formed by mixing an isocyanate-terminated prepolymer (hereinafter sometimes simply referred to as prepolymer), a curing agent, and a hollow body to form a polyurethane resin molded body, and then slicing the polyurethane resin molded body, and which has countless voids formed inside. Here, the polyurethane sheet refers to a polyurethane-based resin containing polyurethane and polyurethane polyurea. The polyurethane sheet used for the polishing layer 211 has a thickness of 0.5 to 2 mm, a Shore D hardness of 20.0 to 70.0, preferably 35.0 to 65.0, and a density of 0.60 to 1.10 g / cm³. ３ These can be set accordingly. By setting the Shore D hardness of the polishing layer 211 within the above range, the occurrence of scratches can be suppressed. The base layer 212 is not particularly limited, but a urethane sponge can be used, and commercially available polyurethane sponges can be used as such a urethane sponge. Alternatively, a polyurethane sheet similar to that of the polishing layer 211 may be used as the base layer 212. The urethane sponge used for the base layer 212 may have a thickness of 0.5 to 2 mm, a Shore A hardness of 20.0 to 75.0, preferably 45.0 to 65.0, and a density of 0.20 to 0.70 g / cm³. ３ Each of these can be set accordingly. The adhesive layer 213 has a pressure-sensitive adhesive, such as an acrylic adhesive, formed on the front and back surfaces of a core material made of polyethylene terephthalate (PET). There are no particular restrictions on the adhesive layer 213, and any double-sided tape known in the art can be arbitrarily selected and used.

[0079] Multiple concentric circular grooves 214 are formed on the polishing surface 211a of the polishing layer 211. Such circular grooves 214 formed on the polishing surface 211a are conventionally known and have the effect of improving polishing performance by retaining slurry inside them when polishing the workpiece 203. The center of the circular grooves 214 on the polishing surface 211a may be set at the center of the polishing pad 201, or it may be set at a distance from the center of the polishing pad 201. There are no limitations on the pitch or cross-sectional shape of adjacent circular grooves 214, but here the cross-section of each groove is made to be approximately rectangular. In addition to the circular grooves 214, radial grooves formed radially from the center of the polishing pad 201 or grid grooves formed in a grid pattern may be provided, and these grooves have the effect of discharging polishing debris and other materials generated during polishing to the outside of the polishing pad 201 together with the slurry.

[0080] Figure 21 shows a plan view of the base layer 212, and the adhesive surface 212a on the polishing layer 211 side of the base layer 212 is provided with a plurality of radial grooves 215 formed radially from the center of the base layer 212. There are no limitations on the cross-sectional shape of the radial grooves 215, but here the cross-section of each groove is approximately rectangular. In this embodiment, the ends of the radial grooves 215 on the center side of the base layer 212 are separated from each other, and a flat portion 216a is formed in the central part of the base layer 212. The flat portion 216a is provided inside the movement range M of the workpiece 203 and the retainer ring 207, and in this embodiment, the movement range M is a region in the range of 7% to 98% of the radius from the center of the polishing pad 201, and the range of the region differs depending on the polishing device 202 used. The radial grooves 215 are formed in the radial direction, and when each radial groove 215 is extended toward the center of the base layer 212, they intersect at the center of the base layer 212.

[0081] On the other hand, the radial grooves 215 are formed such that the outer peripheral end of the base layer 212 does not reach the outer peripheral edge of the base layer 212, and are provided outside the range of movement M of the workpiece 203 and retainer ring 207 that move relative to the polishing pad 201. By not providing the outer peripheral end of the base layer 212 in the radial grooves 215 to the outer peripheral edge of the base layer 212, holes formed by the radial grooves 215 are prevented from forming on the side surface of the polishing pad 201 after the polishing layer 211 and the base layer 212 are bonded by the adhesive layer 213. As a result, when the workpiece 203 is polished by the polishing pad 201, slurry S that has flowed down to the side surface of the polishing pad 201 is prevented from entering between the base layer 212 and the adhesive layer 213 via the radial grooves 215, thereby preventing the base layer 212 and the adhesive layer 213 from peeling off during polishing. On the other hand, by providing the outer peripheral end of the base layer 212 in the radial groove 215 to the outside of the movement range M of the workpiece 203, the stress when the workpiece 203 is pressed against the polishing pad 201 is distributed, and waviness can be reduced. In this embodiment, eight radial grooves 215 are formed, and the angle between adjacent radial grooves 215 is set to 45°. When adjacent radial grooves 215 are spaced apart in this way, it is desirable to form the central end of the base layer 212 of the radial groove 215 to the inside of the movement range M. This distributes the stress when the workpiece 203 is pressed against the polishing pad 201, and waviness can be reduced. The number of radial grooves 215, the groove width of the radial grooves 215, and the position of the central end of the base layer 212 of each radial groove 215 can be set in various ways depending on the hardness of the polishing layer 211 and base layer 212, and the pressure applied when the workpiece 203 is pressed against it. The groove depth of the radial grooves 215 is not particularly limited, but is preferably 20% or more of the thickness of the base layer 212, more preferably 30% or more, and even more preferably 50% or more. When the groove depth of the radial grooves 215 is 20% or more of the thickness of the base layer 212, the stress when the workpiece 203 is pressed against the polishing pad 201 is more easily distributed, making it easier to reduce waviness. It is also possible to slightly incline the radial grooves 215 with respect to the radial direction.

[0082] Figure 22 shows a plan view of the base material layer 212 of the polishing pad 201 according to the sixth embodiment, and compared to the embodiment in Figure 21, the angle between adjacent radial grooves 215 is set to be smaller. In this embodiment, the angle between radial grooves 215 is set to 22.5°, and accordingly, long radial grooves 215a and short radial grooves 215b are provided alternately. Similar to the embodiment in Figure 21, the ends of the long radial grooves 215a on the central side of the base material layer 212 are formed to the inside of the movement range M, while the ends of the short radial grooves 215b on the central side of the base material layer 212 are kept inside the movement range M. With this configuration, the radial grooves 215 do not come too close to each other near the flat portion 216a of the base material layer 212, preventing the central part of the polishing pad 201 from being excessively deformed by the workpiece 203, and reducing waviness. In contrast, if the central end of the base layer 212 of all radial grooves 215 is set to the same position, the radial grooves 215 will come into close proximity near the flat portion 216a of the base layer 212, which may cause the polishing pad 201 to deform excessively and result in waviness. Furthermore, excessive deformation near the flat portion 216a may impair the flatness of the edges of the workpiece 203 after polishing. The angle between radial grooves 215a and 215b, and the position of the central end of the base layer 212 of each radial groove 215 can be set in various ways depending on the hardness of the polishing layer 211 and base layer 212, and the pressure applied to the workpiece 203.

[0083] By using the polishing pad 201 having the above configuration, the waviness generated by polishing the workpiece 203 can be reduced. Considering the principle of waviness generation, when polishing the workpiece 203 with the polishing device 202, the workpiece 203 is pressed against the polishing pad 201, and the workpiece 203 is rotated while revolving around the polishing pad 201. At that time, concentric airbags A provided on the holding platen 205 apply different radial pressures to the workpiece 203. When the workpiece 203 is pressed by the holding platen 205 equipped with multiple airbags A in this way, at the boundary position between adjacent airbags A, the pressure from each airbag A is not transmitted to the workpiece 203, and the pressing force at that boundary position becomes lower than at other parts. As a result, in the polishing pad 201 pressed by the workpiece 203, the repulsive force from the polishing pad 201 is concentrated at the part corresponding to the boundary position of the airbags A, and that part may bulge. As a result, the bulging portion of the polishing pad 201 causes excessive polishing of the portion of the workpiece 203 corresponding to the boundary position of airbag A, which is thought to generate a wavy surface consisting of concentric irregularities formed along the boundary position of airbag A. In other words, the polishing pad of the present invention is suitable for polishing devices equipped with a holding platen in which a plurality of concentrically arranged airbags can each press the workpiece with the required pressure.

[0084] In this embodiment, the polishing pad 201 has radial grooves 215 on the adhesive surface 212a of the base layer 212, and a flat portion 216a formed in the central part of the base layer 212, thereby dispersing the repulsive force when the object to be polished 203 is pressed against the polishing pad 201. As a result, the repulsive force from the polishing pad 201 does not concentrate in the area corresponding to the boundary of the airbag A, and the waviness caused by the concentrically arranged airbag A is prevented.

[0085] Figure 23 shows a cross-sectional view of the polishing pad 201 according to the seventh embodiment, and compared to the fifth and sixth embodiments described above, radial grooves 215 are provided on the adhesive surface 211b on the base layer 212 side of the polishing layer 211. The shape and arrangement of the radial grooves 215 can be the same as those of the polishing pad 201 according to the fifth and sixth embodiments, that is, the ends of the radial grooves 215 on the central side of the polishing layer 211 are separated from each other so that a flat portion 216b is formed in the central part of the polishing layer 211, and the ends of the radial grooves 215 on the outer circumference side of the polishing layer 211 are formed so that they do not reach the outer edge of the polishing layer 211. With this configuration, the radial grooves 215 do not come too close to each other near the flat portion 216b of the polishing layer 211, preventing the central part of the polishing pad 201 from being excessively deformed by the workpiece 203, and reducing waviness. Here, the lower limit of the groove depth of the radial grooves 215 is preferably 15% or more, or 20% or more, of the thickness of the polishing layer 211, and the upper limit is preferably 40% or less, or 35% or less. When the groove depth of the radial grooves 215 is within the above numerical range, the stress when the workpiece 203 is pressed against the polishing pad 201 is more easily distributed, and waviness is more easily reduced. The groove depth of the radial grooves 215 can be appropriately set according to the thickness of the polishing layer 211 and the groove depth of the circular grooves 214, since the circular grooves 214 and radial grooves 215 are formed on the polishing surface 211a and the adhesive surface 211b, respectively. Preferably, the central end of the polishing layer 211 in the radial groove 215 is located at a distance of 5% or more, 10% or more, or 13% or more of the radius from the center of the polishing layer 211, and preferably the outer peripheral end of the polishing layer 211 in the radial groove 215 is located at a distance of 99% or less, 95% or less, or 93% or less of the radius from the center of the polishing layer 211. When each end of the radial groove 215 is within the above numerical range, the stress when the workpiece 203 is pressed against the polishing pad 201 is more easily distributed, and wavy is more easily reduced.

[0086] The following describes a method for manufacturing a polishing pad 201 comprising the polishing layer 211 and the base layer 212. The polyurethane sheet constituting the polishing layer 211 is manufactured by a prepolymer method, in which a polyurethane composition is obtained by adding and mixing an isocyanate-terminated prepolymer, which is a reaction intermediate between a polyol component and an isocyanate component, with a curing agent (chain extender) such as diamines or diols, a foaming agent, a catalyst, etc., and curing the resulting polyurethane composition. The prepolymer method includes, at least, a preparation step of preparing a urethane bond-containing isocyanate compound as an isocyanate-terminated prepolymer, a curing agent, and a hollow body; at least a mixing step of mixing the urethane bond-containing isocyanate compound and the curing agent to obtain a mixed liquid for molding a molded article; and a molded article molding step of molding a polyurethane polyurea resin molded article from the mixed liquid for molding a molded article. As a method for manufacturing the urethane sponge constituting the base layer 212, for example, a method of curing the composition while foaming it by heating a composition containing a resin prepolymer, a curing agent, and a foaming agent. The prepolymer and curing agent used in the manufacture of the sponge can be those exemplified in the method for manufacturing the polishing layer. Then, by performing a polishing layer forming step to obtain a polishing layer 211 by slicing the polyurethane polyurea resin molded body obtained by such a prepolymer method to a predetermined thickness, a base layer forming step to obtain a base layer 212 by slicing a urethane sponge to a predetermined thickness, a groove forming step to form the circular groove and radial groove in the polishing layer 211 and the base layer 212, and a cutting step to bond the polishing layer 211 and the base layer 212 and then cut them into a circular shape, a disc-shaped polishing pad 201 according to this embodiment can be obtained.

[0087] In the preparation step for manufacturing the polishing layer 211, at least a urethane bond-containing isocyanate compound, a curing agent, and a hollow body are used as raw materials for the polyurethane resin molded article. Furthermore, a polyol compound may be used together with the above components, and other components may be used in combination as long as they do not impair the effects of the present invention. The urethane bond-containing isocyanate compound prepared in this preparation step is a compound obtained by reacting the following polyisocyanate compound and polyol compound under commonly used conditions, and contains a urethane bond and an isocyanate group in its molecule. In addition, other components may be included in the urethane bond-containing isocyanate compound as long as they do not impair the effects of the present invention. As the urethane bond-containing isocyanate compound, a commercially available one may be used, or one synthesized by reacting a polyisocyanate compound and a polyol compound may be used. There are no particular restrictions on the above reaction, and an addition polymerization reaction may be carried out using methods and conditions known in the production of polyurethane resins. For example, it can be manufactured by adding a polyisocyanate compound heated to 50°C to a polyol compound heated to 40°C while stirring under a nitrogen atmosphere, raising the temperature to 80°C after 30 minutes, and then reacting at 80°C for another 60 minutes.

[0088] First, the term "polyisocyanate compound" refers to a compound having two or more isocyanate groups in its molecule. Furthermore, there are no particular limitations on what constitutes a polyisocyanate compound, as long as it has two or more isocyanate groups in its molecule. For example, diisocyanate compounds having two isocyanate groups in their molecule include m-phenylenediisocyanate, p-phenylenediisocyanate, 2,6-tolylenediisocyanate (2,6-TDI), 2,4-tolylenediisocyanate (2,4-TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), 3,3'-dimethoxy-4,4'-biphenyldiisocyanate, and 3,3'-dimeth Examples of polyisocyanate compounds include diphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate, and ethyridine diisothiocyanate. Furthermore, diisocyanate compounds are preferred as polyisocyanate compounds, with 2,4-TDI, 2,6-TDI, MDI, and hydrogenated MDI being more preferred, and particularly preferred to contain 2,4-TDI and / or 2,6-TDI. These polyisocyanate compounds may be used individually or in combination of multiple polyisocyanate compounds.

[0089] Next, the polyol compound refers to a compound having two or more alcoholic hydroxyl groups (OH) in its molecule. Examples of polyol compounds used in the synthesis of the urethane bond-containing isocyanate compound include diol compounds such as ethylene glycol, diethylene glycol (DEG), and butylene glycol, triol compounds, etc.; polyether polyol compounds such as poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) (PTMG), polyethylene glycol (PEG), and polypropylene glycol (PPG); polyester polyol compounds such as reaction products of ethylene glycol and adipic acid or reaction products of butylene glycol and adipic acid; polycarbonate polyol compounds, polycaprolactone polyol compounds, etc., and combinations thereof. In addition, trifunctional propylene glycol to which ethylene oxide has been added can also be used. Among these, combinations of polyester polyols such as PTMG and DEG, PPG and DEG, or reaction products of butylene glycol and adipic acid with DEG are preferred. The polyol compound may be used alone, or multiple polyol compounds may be used in combination.

[0090] Here, the NCO equivalent of the isocyanate-terminated prepolymer, which represents the molecular weight of PP (isocyanate-terminated prepolymer) per NCO group, is preferably 200 to 800, more preferably 300 to 700, and even more preferably 400 to 600. Specifically, the NCO equivalent of the isocyanate-terminated prepolymer can be determined as follows: NCO equivalent of isocyanate-terminated prepolymer = (parts by mass of polyisocyanate compound + parts by mass of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound × parts by mass of polyisocyanate compound / molecular weight of polyisocyanate compound) - (number of functional groups per molecule of polyol compound × parts by mass of polyol compound / molecular weight of polyol compound)]

[0091] As the curing agent (also called a chain extender), for example, a polyamine compound and / or a polyol compound can be used. A polyamine compound means a compound having two or more amino groups in its molecule, and aliphatic or aromatic polyamine compounds, especially diamine compounds, can be used. For example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA), and polyamine compounds having a structure similar to MOCA can be mentioned. Furthermore, the polyamine compound may also have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. As the polyamine compound, diamine compounds are preferred, more preferably MOCA, diaminodiphenylmethane, and diaminodiphenylsulfone, with MOCA being particularly preferred. The polyamine compound may be used alone or in combination of multiple polyamine compounds. To facilitate mixing with other components and / or to improve the uniformity of the bubble diameter in the subsequent molded article formation process, it is preferable to degas the polyamine compound under reduced pressure while heated as necessary. As a method for degassing under reduced pressure, any method known in the production of polyurethane may be used, for example, degassing can be performed using a vacuum pump at a vacuum of 0.1 MPa or less. When a solid compound is used as the curing agent (chain extender), it can be degassed under reduced pressure while being melted by heating.

[0092] Furthermore, any polyol compound such as diol compounds or triol compounds can be used as a curing agent without particular restrictions. It may also be the same as or different from the polyol compound used to form the isocyanate-terminated prepolymer. Specific examples include low molecular weight diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol, and high molecular weight polyol compounds such as poly(oxytetramethylene) glycol, polyethylene glycol, and polypropylene glycol. The polyol compounds may be used individually or in combination of multiple polyol compounds.

[0093] Here, the components are mixed so that the R value, which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the isocyanate groups present at the ends of the urethane bond-containing isocyanate compound, is 0.60 to 1.40. The R value is preferably 0.65 to 1.30, and more preferably 0.70 to 1.20.

[0094] The term "hollow body" refers to a microsphere having voids. Microspheres include spherical, elliptical, and nearly spherical shapes. Examples of hollow bodies include unexpanded, heat-expandable microspheres consisting of an outer shell (polymer shell) made of a thermoplastic resin and a low-boiling-point hydrocarbon enclosed within the outer shell, or unexpanded, heat-expandable microspheres that have been heated and expanded. As the polymer shell, thermoplastic resins such as acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methyl methacrylate copolymer, and vinyl chloride-ethylene copolymer can be used, as disclosed in Japanese Patent Publication No. 57-137323, etc. Similarly, as the low-boiling-point hydrocarbon enclosed within the polymer shell, examples such as isobutane, pentane, isopentane, and petroleum ether can be used.

[0095] Next, the mixing process will be described. In this mixing process, the urethane bond-containing isocyanate compound as an isocyanate-terminated prepolymer, the curing agent, and the hollow body, which were prepared in the preparation process, are supplied to the mixer and stirred and mixed. The mixing process is carried out under conditions where the mixture is heated to a temperature that ensures the fluidity of each component. There are no particular restrictions on the mixing order, but it is preferable to prepare a mixture of the urethane bond-containing isocyanate compound and the hollow body, and a mixture of the curing agent and other components as needed, and to supply both mixtures to the mixer and stir them together. In this way, a mixture for molding a molded article is prepared.

[0096] Next, in the molding process, the mixed liquid for molding the molded body prepared in the mixing process is poured into a mold at 50 to 130°C and cured to form a polyurethane resin molded body. At this time, the mixed liquid hardens as the isocyanate-terminated prepolymer and curing agent react to form polyurethane resin.

[0097] The sponge used in the base layer 212 may be manufactured by known methods or obtained commercially. Polyurethane foam manufactured by Inoac Corporation, polyurethane foam manufactured by Sekisui Chemical Co., Ltd., or polyurethane foam manufactured by NHK Spring Co., Ltd. may be used.

[0098] Next, in the polishing layer formation step, the polyurethane resin molded body obtained is sliced ​​into a sheet of the required thickness to obtain the polishing layer 211. Similarly, in the base layer formation step, the urethane sponge obtained is sliced ​​into a sheet of the required thickness to obtain the base layer 212. The polishing layer 211 and base layer 212 obtained in this way are rectangular sheets. In the groove formation step, circular grooves 214 are formed on the surface of the sheet-shaped polishing layer 211 corresponding to the polishing surface, and radial grooves 215 are formed on at least one surface of the base layer 212 corresponding to the adhesive surface, the base layer 212 holding surface, or the adhesive surface of the polishing layer 211. Subsequently, the polishing layer 211 with the circular grooves 214 and the base layer 212 are bonded together using double-sided tape or the like that constituting the adhesive layer 213. Subsequently, in the cutting process, the bonded polishing layer 211 and the base layer 212 are cut into a circular shape to obtain a disc-shaped polishing pad 201.

[0099] Figures 24 and 25 show the experimental results for the polishing pad 201 according to the seventh embodiment (Example 4) and a comparative polishing pad 201 (Comparative Example 3). Figure 24 shows the amount of wavy in the response area of ​​each airbag, and Figure 25 is a graph showing the surface state of the workpiece 203 polished using the polishing pad 201.

[0100] Example 4 The polishing pad 201 in Example 4 had a diameter of 740 mm. The polishing layer 211 was made of a polyurethane sheet with a density of 0.88 g / cm³, a D hardness of 44.0, and a thickness of 1.6 mm. The base layer 212 was made of a urethane sponge with a thickness of 1.0 mm and a Shore A hardness of 71. The adhesive layer was made of double-sided tape with a PET core material that was 0.05 mm thick. The storage modulus of the polishing layer 211 (at 40°C) was 98.2 MPa, while the storage modulus of the base layer 212 (at 40°C) was 7.2 MPa. As a result, the ratio of the storage modulus of the polishing layer 211 to the storage modulus of the base layer 212 was 13.6. Of the circular grooves 214 formed on the polishing surface 211a of the polishing layer 211, the innermost circular groove 214 was positioned at a radius of 11 mm from the center of the polishing pad 201, and grooves with a pitch of 1.7 mm, a width of 0.4 mm, and a depth of 0.8 mm were provided outside of it. At this time, the radius of the outermost circular groove 214 was 358.4 mm. In addition, the radial grooves 215 formed on the adhesive surface 211b of the polishing layer 211 were set to have 32 grooves (groove angle pitch of 11.25°), a groove width of 1.5 mm, and a groove depth of 0.5 mm. The end of each radial groove 215 on the side closer to the center of the polishing layer 211 was at a distance of 55 mm from the center of the polishing layer 211, which was at a position of 15% of the radius of the polishing layer 211. In addition, the end of each radial groove 215 on the side closer to the outer circumference of the polishing layer 211 was at a distance of 335 mm from the center of the polishing layer 211, which was at a position of 91% of the radius of the polishing layer 211.

[0101] Comparative Example 3: In contrast to Example 4, the polishing pad 201 in Comparative Example 3 used a polishing layer 211 and a base layer 212 having the same hardness as the polishing pad 201 in Example 4, and also used the same adhesive layer. Circular grooves 214 were formed on the polishing surface 211a of the polishing layer 211 of Comparative Example 3 in the same arrangement as in Example 4, while radial grooves 215 were not formed on the adhesive surface 211b.

[0102] Next, the polished layers 211 of Example 4 and Comparative Example 3 were obtained as follows: A first isocyanate-terminated urethane prepolymer with an NCO equivalent of 560 was prepared by reacting 2,4-tolylene diisocyanate (TDI), polypropylene glycol (PPG) with a number average molecular weight of 1000, and diethylene glycol (DEG). A second isocyanate-terminated urethane prepolymer with an NCO equivalent of 600 was prepared by reacting 2,4-tolylene diisocyanate (TDI), a polyester polyol with a number average molecular weight of 2000 obtained by reacting adipic acid and 1,4-butanediol, and diethylene glycol (DEG). Subsequently, the prepared first and second isocyanate-terminated urethane prepolymers were mixed in a weight ratio of 50:50 to prepare a mixed isocyanate-terminated urethane prepolymer with an NCO equivalent of 580. Furthermore, 3.5 parts of unexpanded microspheres with an average particle size of 8.5 μm, in which the outer shell consists of an acrylonitrile-vinylidene chloride copolymer and isobutane gas is contained within the shell, were added and mixed to 100 parts of the prepared mixed isocyanate-terminated urethane prepolymer to obtain a urethane prepolymer mixture. The obtained urethane prepolymer mixture was placed in the first liquid tank and kept warm at 80°C. Separately from the first liquid tank, 20.9 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (MOCA) as a curing agent were placed in the second liquid tank, heated and melted at 120°C, and mixed to obtain a curing agent molten solution. Next, the liquids from the first and second liquid tanks were injected through the respective inlets of a mixer equipped with two inlets, and stirred to obtain a mixed solution. At this time, the mixing ratio was adjusted so that the R value, which represents the equivalent ratio of amino groups and hydroxyl groups in the curing agent to the isocyanate groups at the ends of the urethane prepolymer, was 0.90. The resulting mixture was poured into a mold preheated to 80°C and primary cured at 80°C for 30 minutes. The formed block-shaped molded product was removed from the mold and secondary cured in an oven at 120°C for 4 hours to obtain a polyurethane resin molded product. After the obtained polyurethane resin molded product was allowed to cool to 25°C, it was heated again in an oven at 120°C for 5 hours and then sliced ​​to a thickness of 1.6 mm to obtain a polished layer 211.

[0103] On the other hand, the base layer 212 of Example 4 and Comparative Example 3 was obtained by purchasing polyurethane foam from Sekisui Chemical Co., Ltd. and buffing it to a thickness of 1.0 mm.

[0104] The density (g / cm³) of the polishing layer 211 in Example 4 and Comparative Example 3 was measured in accordance with the Japanese Industrial Standard (JIS-K-6505). The Shore D hardness of the polishing layer 211 made of polyurethane sheet was measured using a D-type hardness tester in accordance with the Japanese Industrial Standard (JIS-K-6253). Here, the measurement sample was obtained by stacking multiple polishing layers 211 as necessary, so that the total thickness was at least 4.5 mm. On the other hand, the Shore A hardness of the base layer 212 made of urethane sponge was measured using an A-type hardness tester in accordance with the Japanese Industrial Standard (JIS-K-7311). Here, the measurement sample was obtained by stacking multiple base layer 212 as necessary, so that the total thickness was at least 4.5 mm. (Dynamic Viscoelasticity Test) A dynamic viscoelasticity test was performed on the polishing layer 211 and base layer 212 based on the following measurement conditions. The polished layer 211 and base layer 212, kept in a constant temperature and humidity chamber at a temperature of 23°C (±2°C) and relative humidity of 50% (±5%) for 40 hours, were used as samples. The polished layer was measured in tensile mode and the base layer in compression mode under normal atmospheric conditions (dry state). (Measurement conditions: polished layer) Measurement device: RSA-G2 (TA Instruments Co., Ltd.) Sample size (polished layer): 5 cm (length) x 0.5 cm (width) x 0.16 cm (thickness) Test length: 1 cm Test mode: tensile mode Frequency: 10 rad / s (1.6 Hz) Measurement temperature: 20-100°C Heating rate: 5°C / min Strain range: 0.10% Initial load: 148 g Measurement interval: 2 points / °C (Measurement conditions: substrate layer) Measurement device: RSA-G2 (TA Instruments Co., Ltd.) Frequency: 1 Hz Sample size (substrate layer): 1 cm (length) x 1 cm (width) x 0.1 cm (thickness) Test mode: compression Measurement temperature: 20-100°C Heating rate: 3°C / min Strain range: 0.10% Initial load: 100 g

[0105] The polishing pads 201 obtained in the above-mentioned Example 4 and Comparative Example 3 were subjected to polishing on a Cu film substrate under the following polishing conditions. When the predetermined polishing was completed, the polished surface of the workpiece 203 was measured, and it was determined from the experimental results shown in Figures 24 and 25 whether or not a wavy surface had been formed on the polished surface of the workpiece 203.

[0106] (Polishing conditions) Polishing machine: F-REX300X (manufactured by Ebara Corporation) Disk: 34J (manufactured by KINIK Corporation) Rotation speed: (Holding platen) 90 rpm, (Polishing platen) 81 rpm Polishing pressure: 2.7 psi Polishing agent temperature: 20℃ Polishing agent discharge rate: 350 ml / min Polishing agent: CSL-9044C (CSL-9044C concentrate: pure water = weight ratio 1:9 mixture used) (manufactured by Fujifilm Planar Solutions Co., Ltd.) Workpiece 203 (metal film): Cu film substrate (disc shape with a diameter of 300 mm) Polishing time: 60 seconds Pad break: 20N 60 minutes Conditioning: In-situ, 20N Here, the workpiece 203 to be polished is held so that its center coincides with the holding platen 205 that constitutes the polishing machine, and the rotation center of the holding platen 205 is set at a position 125 mm away from the rotation center of the polishing platen 204. The holding platen 205 of the polishing machine is provided with airbags A1 to A6, which are provided in the radially outward direction in the ranges of A1: 0-20 mm, A2: 20-50 mm, A3: 50-75 mm, A4: 75-100 mm, A5: 100-120 mm, and A6: 120-130 mm, and a retainer ring 207 is provided on the outer circumference of airbag A6.

[0107] Figure 24 shows the measurement results for the amount of wavy in the response area of ​​each airbag. The horizontal axis represents the pressure response areas of the first to sixth airbags A1 to A6, corresponding to Figure 20, and the vertical axis represents the amount of wavy in each pressure response area. The pressure response area on the horizontal axis refers to the range over which the pressure applied by each airbag A1 to A6 of the holding platen 205 to the workpiece 203 is transmitted. Here, the ranges are from the center of the workpiece 203 outward in the radial direction: A1: 0-30 mm, A2: 15-65 mm, A3: 45-87 mm, A4: 70-112 mm, A5: 95-130 mm, A6: 115-140 mm. The reason why the pressure response areas of each airbag A1 to A6 overlap is that each airbag A1 to A6 exerts a certain degree of stress on the workpiece 203. The wavy amount on the vertical axis represents the difference between the maximum and minimum polishing rates, and is calculated as the difference between the maximum and minimum polishing rates within the range of the airbag response area. From the experimental results, it can be seen that when using the polishing pad 201 of Example 4, the wavy amount in each response area is reduced compared to when using the polishing pad of Comparative Example 3.

[0108] Figure 25 is a graph showing the surface condition of the workpiece 203. The horizontal axis represents the distance from the center of the workpiece 203 towards the radial outer circumference, and the vertical axis represents the polishing rate at positions corresponding to the distance from the center of the workpiece 203. In other words, the vertical axis represents the surface condition of the workpiece. For convenience, Comparative Example 3 and Example 4 are shown side by side to facilitate comparison of the surface conditions of the workpieces. Here, the boundary positions of airbags A1 to A6 on the holding platen 205 correspond to positions of 20 mm, 50 mm, 75 mm, 100 mm, 120 mm, and 130 mm relative to the center of the workpiece 203, respectively. According to the experimental results, when using the polishing pad 201 of Example 4, the difference in polishing rate between the boundary positions of each airbag A and the intermediate portions between each boundary position was smaller compared to when using the polishing pad 201 of Comparative Example 3, confirming that the waviness caused by the airbag boundaries was reduced.

[0109] Figure 26 shows a cross-sectional view of the polishing pad 201 according to the eighth embodiment, and compared to the fifth to seventh embodiments described above, radial grooves 215 are provided on the holding surface 212b on the polishing platen 204 side of the base layer 212. The shape and arrangement of the radial grooves 215 can be the same as those of the polishing pad 201 according to the fifth to seventh embodiments, that is, the ends of the radial grooves 215 on the central side of the base layer 212 are separated from each other so that a flat portion 216c is formed in the central part of the base layer 212, and the ends of the radial grooves 215 on the outer circumference side of the base layer 212 are formed so that they do not reach the outer edge of the base layer 212. This configuration prevents the radial grooves 215 from coming into excessive proximity near the flat portion 216c of the base layer 212, thereby preventing the central portion of the polishing pad 201 from being excessively deformed by the workpiece 203, reducing waviness, and ensuring that the flatness of the edges of the workpiece 203 is not impaired due to excessive deformation near the flat portion 216a.

[0110] Furthermore, even if the polishing device 202 is configured with a pressure adjustment means composed of multiple pressing means arranged concentrically, instead of the airbag A of the holding platen 205, there is still a possibility of waviness occurring at the boundary between each pressing means. Therefore, by using the polishing pad 201 according to the present invention, it is possible to suppress the occurrence of such waviness. In addition, in the polishing pad 201 of each embodiment, it is also possible to fill the radial grooves 215 with the required material such as resin or rubber. As the resin, UV-curable resin, urethane resin, silicone resin, acrylic resin, etc. can be used, and as the rubber, natural rubber, nitrile rubber, polyurethane rubber, etc. can be used. The materials may be used individually or in combination of multiple materials. By filling the radial grooves 215 with resin or rubber in this way, the repulsive force when the object to be polished 203 is pressed against the polishing pad 201 can be made different between the portion where the base layer 212 and the polishing layer 211 are formed and the portion where the resin or rubber-filled radial grooves 215 are formed, and the same effect as the polishing pad 201 of each embodiment can be expected.

[0111] The polishing pad according to the ninth embodiment will be described below. In each figure, the same components are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensions of each part in each figure are exaggerated for illustrative purposes, and their ratios differ from those of actual parts. Figure 27 shows a perspective view of a polishing apparatus 302 equipped with a polishing pad 301 according to an embodiment of the present invention, which is used to polish an object to be polished 303 such as a semiconductor substrate. The polishing apparatus 302 includes a polishing platen 304 provided below to support the polishing pad 301, and a holding platen 305 provided above to hold the object to be polished 303.

[0112] The polishing pad 301 and the workpiece 303 are each substantially disc-shaped, with the polishing pad 301 having a larger diameter than the workpiece 303. The upper surface of the polishing pad 301 has a polishing surface that contacts the workpiece 303 to perform polishing. Slurry S is supplied to this polishing surface from the slurry supply means 306. The lower surface of the polishing pad 301 is fixed to the polishing platen 304 by double-sided tape or the like.

[0113] As shown in Figures 28 and 29, the holding platen 305 comprises a disc-shaped top ring 305a and a plurality of airbags A arranged concentrically on the lower surface of the top ring 305a, so that the disc-shaped workpiece 303 is held in close contact with the lower surface of the airbags A.

[0114] As shown in Figure 28, the holding platen 305 comprises a disc-shaped top ring 305a, an airbag A consisting of a plurality of concentrically arranged compartments on the lower surface of the top ring 305a, and an annular retainer 305b that holds the outer periphery of the airbag A and the workpiece 303. The disc-shaped workpiece 303 is held in close contact with the lower surface of the airbag A inside the retainer 305b.

[0115] The polishing platen 304 and the holding platen 305 are each rotated by a driving means (not shown), and the holding platen 305 is further reciprocated radially from the center position of the polishing platen 304. As a result, the workpiece 303 held by the holding platen 5 slides radially along the polishing surface of the rotating polishing pad 301 while rotating.

[0116] The slurry supply means 306 supplies a slurry, in which abrasive particles are mixed in a required liquid, to the polishing surface of the polishing pad 301. This allows the slurry to penetrate between the polishing surface and the workpiece 303, thereby performing so-called chemical mechanical polishing (CMP).

[0117] Figure 28 shows a cross-sectional view of the polishing apparatus 302 and polishing pad 301 according to this embodiment. Note that the dimensions of each part in each figure are exaggerated for illustrative purposes. The holding platen 305 is equipped with first to sixth airbags A1 to A6 concentrically on the lower surface of the top ring 305a, and each airbag A has a substantially rectangular cross-section, and its flat lower surface is processed to allow it to adhere closely to and hold the surface of the workpiece 303 to be polished.

[0118] As shown in Figure 29, the first to sixth airbags A1 to A6 are arranged concentrically and consist of a circular first airbag A1 located in the center and ring-shaped second to sixth airbags A2 to A6 surrounding the first airbag A1. Each airbag A (A1 to A6) is capable of applying different pressures (P1 to P6) to the workpiece 303. The pressure applied to the first to sixth airbags A1 to A6 can be adjusted according to the workpiece 303 to be polished and various polishing conditions, and since such a holding platen 305 is known from Patent Document 1 and other documents, further detailed explanation will be omitted.

[0119] As shown in Figure 28, the polishing pad 301 comprises a polishing layer 311 having a polishing surface that contacts the workpiece 303, a base layer 312 provided on the side of the polishing layer 311 opposite to the polishing surface and held by the polishing platen 304, and an adhesive layer 313 that bonds the polishing layer 311 and the base layer 312.

[0120] The polishing layer 311 can use a polyurethane sheet. As such a polyurethane sheet, an isocyanate-terminated prepolymer (hereinafter sometimes simply referred to as a prepolymer), a curing agent, and a hollow body are mixed to form a polyurethane resin molded body, and the polyurethane resin molded body is sliced to form a foamed polyurethane sheet having innumerable voids inside, and such a foamed polyurethane sheet can be used. Here, the polyurethane sheet refers to a polyurethane-based resin including polyurethane and polyurethane-polyurea.

[0121] The base material layer 312 can use a urethane sponge. As such a urethane sponge, a commercially available urethane sponge or the like can be used. Note that the same polyurethane sheet as the polishing layer 311 may be used as the base material layer 312.

[0122] As the polyurethane sheet used for the polishing layer 311, the thickness can be set to 0.5 to 2 mm, the Shore D hardness can be set to 20.0 to 70.0, preferably 35.0 to 65.0, and the density can be set to 0.60 to 1.10 g / cm ３ respectively. By setting the D hardness of the polishing layer 311 within the above range, the generation of scratches can be suppressed.

[0123] As the urethane sponge used for the base material layer 312, the thickness can be set to 0.5 to 2 mm, the Shore A hardness can be set to 20.0 to 75.0, preferably 45.0 to 65.0, and the density can be set to 0.20 to 0.70 g / cm ３ respectively.

[0124] Further, the storage elastic modulus (40°C) of the polishing layer 311 is 55 to 400 MPa, preferably 70 to 130 MPa, and the storage elastic modulus (40°C) of the base material layer 312 is 1 to 10 MPa, preferably 2 to 8 MPa. And it is desirable that the ratio of the storage elastic modulus of the polishing layer 311 to the storage elastic modulus of the base material layer 312 is in the range of 2 to 60, preferably 5 to 50. By setting it in this way, it becomes possible to polish the workpiece without damaging the end shape of the workpiece.

[0125] Surface structures such as grooves and through holes can be arbitrarily formed on the polishing surface of the polishing layer 311. These surface structures allow the slurry to be retained on the polishing surface when polishing the workpiece 303, or allow the slurry on the polishing surface to be discharged to the outside. Conventional known shapes can be used as surface structures, such as grid grooves, radial grooves, concentric grooves, and through holes.

[0126] In the aforementioned polishing pad 301, in order to uniformly polish the workpiece 303 while pressing it with a large pressing force, a concentric airbag A is provided on the holding platen 305 to apply different radial pressures to the workpiece 303.

[0127] As described above, when using a holding platen 305 equipped with multiple airbags A, at the boundary position B between adjacent airbags A, the pressure from each airbag A is not transmitted to the workpiece 303, and the pressing force at that position is lower than at other parts. As a result, the rebound force from the polishing pad 301 due to compression is concentrated in the part of the workpiece 303 corresponding to the boundary position B between airbags A, and this part is excessively polished, causing concentric irregularities to form in line with the boundary position B, which is thought to be the cause of the wavy surface.

[0128] In this embodiment, the adhesive layer 313 in the polishing pad has the following configuration. The adhesive layer 313 adheres the base material layer 312 and the polishing layer 311. The adhesive layer 313 may be formed by forming adhesive on the front and back surfaces of a core material made of polyethylene terephthalate (PET). As for the type of adhesive, rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, etc., can be used, and in terms of form, pressure-sensitive type or hot-melt type can be used. When a group of grooves described later is provided in the adhesive layer, an acrylic-based pressure-sensitive type is preferably used. Furthermore, the core material made of polyethylene terephthalate (PET) is not required. There are no particular restrictions on the adhesive layer 313, and it can be arbitrarily selected from various types of double-sided tapes.

[0129] The adhesive layer 313 interposed between the base layer 312 and the polishing layer 311 has a first groove group 332 excavated from the base layer 312 towards the polishing layer 311 and / or a second groove group 331 excavated from the polishing layer 311 towards the base layer 312 (Figure 28). Here, a groove group obviously refers to a group of multiple continuous grooves. In addition, even a single continuous groove in a spiral shape can be referred to as a groove group if multiple adjacent recesses (grooves) are formed in a plane.

[0130] The first groove group 332 and the second groove group 331 may have a wall portion at the position where they reach the periphery of the adhesive layer 313, so that there are no groove groups at the periphery of the adhesive layer 313. In this way, when there are no groove groups at the periphery of the adhesive layer 313, adhesion between the base layer 312 and the polishing layer 311 can be accurately achieved at the periphery, and peeling can be prevented. The first groove group 332 and the second groove group 331 have shapes selected from the group consisting of, for example, grid grooves, radial grooves, spiral grooves, concentric grooves, and holes.

[0131] When polishing is performed using the polishing pad 301 according to this embodiment, the passage area E through which the workpiece 303 passes on the polishing pad 301 is shown in Figure 30. In this embodiment, it is preferable to provide the first groove group 332 and the second groove group 331 at positions on the surface of the adhesive layer 313 corresponding to the passage area E. Figure 31 shows the case of radial grooves. The center of the passage area E is a non-passage area through which the workpiece 303 does not pass. The center positions of the first groove group 332 and the second groove group 331 may coincide with the center of the passage area E, or they may be offset (misaligned) as shown in Figure 32. The groove group shown in Figure 32 represents concentric grooves. The groove group may also be a combination of two or more patterns. Figure 33 shows a combination (overlapping) of grid grooves and spiral grooves, and Figure 34 shows a combination of radial grooves and holes. Of course, it is also acceptable to combine (superimpose) two pernes selected from the group consisting of grid grooves, radial grooves, spiral grooves, concentric grooves, and holes.

[0132] Even with the polishing pad 301 according to the above embodiment, the adhesive layer 313, which has a first group of grooves 332 excavated from the base layer 312 toward the polishing layer 311 and / or a second group of grooves 331 excavated from the polishing layer side 11 toward the base layer 312, is expected to have a reduced repulsive force on the workpiece 303 due to the gaps formed between the base layer 312 and the adhesive layer 313 and / or between the polishing layer 311 and the adhesive layer 313 caused by the presence of the grooves, thereby dispersing the repulsive force on the workpiece 303. For this reason, it can be inferred that even at the position B corresponding to the boundary position B of the airbag A on the workpiece 303, the irregularities generated at the boundary position of the airbag A will be smaller compared to conventional polishing pads, and this is expected to lead to a reduction in waviness.

[0133] In other words, the polishing pad 301 of the ninth embodiment described above is constructed according to the following invention. Firstly, the polishing pad comprises a polishing layer having a polishing surface formed thereon for polishing an object to be polished, and a base layer provided on the opposite side of the polishing surface of the polishing layer and held on a polishing platen of a polishing device, wherein a first group of grooves excavated from the base layer side toward the polishing layer and / or a second group of grooves excavated from the polishing layer side toward the base layer are formed between the base layer and the polishing layer, and an adhesive layer is provided to bond the base layer and the polishing layer, wherein the first group of grooves and the second group of grooves have a wall portion at the position where they reach the periphery of the adhesive layer. Secondly, the first group of grooves and / or the second group of grooves are formed in a range corresponding to the area on the polishing surface where the object to be polished moves. Thirdly, the grooves of the first groove group and the grooves of the second groove group are formed around predetermined positions in areas corresponding to the surface region of the base layer and the surface region of the polishing layer, respectively, and the centers of the first groove group and the centers of the second groove group are not coincident. Fourthly, the grooves of the first groove group and the grooves of the second groove group are concentric, radial, grid-like, spiral, or perforated. Fifthly, the adhesive layer is characterized by having an adhesive layer on the polishing layer side and an adhesive layer on the base layer side via a PET layer.

[0134] The polishing pads according to the 10th and 11th embodiments will be described below. In each figure, the same components are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensions of each part in each figure are exaggerated for illustrative purposes, and their ratios differ from those of actual parts. Figure 35 shows a perspective view of a polishing apparatus 402 equipped with a polishing pad 401 according to an embodiment of the present invention, which is used to polish an object to be polished 403 such as a semiconductor substrate. The polishing apparatus 402 includes a polishing platen 404 provided below to support the polishing pad 401, and a holding platen 405 provided above to hold the object to be polished 403.

[0135] The polishing pad 401 and the workpiece 403 are each substantially disc-shaped, with the polishing pad 401 having a larger diameter than the workpiece 403. The upper surface of the polishing pad 401 has a polishing surface that contacts the workpiece 403 to perform polishing. Slurry is supplied to this polishing surface from a slurry supply means 406. The lower surface of the polishing pad 401 is fixed to the polishing platen 404 by double-sided tape or the like.

[0136] As shown in Figures 36 and 37, the holding platen 405 comprises a disc-shaped top ring 405a and a plurality of airbags A arranged concentrically on the lower surface of the top ring 405a, so that the disc-shaped workpiece 403 is held in close contact with the lower surface of the airbags A.

[0137] As shown in Figure 36, the holding platen 405 comprises a disc-shaped top ring 405a, an airbag A consisting of a plurality of concentrically arranged compartments on the lower surface of the top ring 405a, and an annular retainer ring 405b that holds the airbag A and the outer periphery of the workpiece 403. The disc-shaped workpiece 403 is held in close contact with the lower surface of the airbag A inside the retainer ring 405b.

[0138] The polishing platen 404 and the holding platen 405 are each rotated by a drive mechanism (not shown), and the holding platen 405 is further reciprocated radially from the center position of the polishing platen 404. As a result, the workpiece 403 held by the holding platen 405 slides radially along the polishing surface of the rotating polishing pad 401 while rotating.

[0139] The slurry supply means 406 supplies a slurry, in which abrasive particles are mixed in a required liquid, to the polishing surface of the polishing pad 401. This allows the slurry to penetrate between the polishing surface and the workpiece 403, thereby performing so-called chemical mechanical polishing (CMP).

[0140] Figure 36 shows a cross-sectional view of a polishing apparatus 402 and polishing pad 401 according to the tenth embodiment. Note that the dimensions of each part in each figure are exaggerated for illustrative purposes. The holding platen 405 is equipped with first to sixth airbags A1 to A6 concentrically on the lower surface of the top ring 405a, and each airbag A has a substantially rectangular cross-section, and its flat lower surface is processed to allow it to adhere closely to and hold the surface of the workpiece 403 to be polished.

[0141] As shown in Figure 37, the first to sixth airbags A1 to A6 are arranged concentrically and consist of a circular first airbag A1 located in the center and ring-shaped second to sixth airbags A2 to A6 surrounding the first airbag A1. Each airbag A (A1 to A6) is capable of applying different pressures (P1 to P6) to the workpiece 403 to be polished.

[0142] Furthermore, the pressure applied to the first to sixth airbags A1 to A6 can be adjusted according to the workpiece 403 to be polished and various polishing conditions, and since such a holding plate 405 is known from the aforementioned Patent Document 1, etc., further detailed explanation will be omitted.

[0143] As shown in Figure 36, the polishing pad 401 comprises a polishing layer 411 having a polishing surface that contacts the workpiece 403, a base layer 412 provided on the side of the polishing layer 411 opposite to the polishing surface and held by the polishing platen 404, and an adhesive layer 413 that bonds the polishing layer 411 and the base layer 412. The adhesive layer 413 can be made of a core material made of polyethylene terephthalate (PET) with a pressure-sensitive adhesive such as an acrylic adhesive formed on the front and back surfaces, respectively. There are no particular restrictions on the adhesive layer 413, and it can be arbitrarily selected from various types of double-sided tapes.

[0144] A polyurethane sheet can be used for the polishing layer 411. As such a polyurethane sheet, a foamed polyurethane sheet can be used, which is formed by mixing an isocyanate-terminated prepolymer (hereinafter sometimes simply referred to as prepolymer), a curing agent, and a hollow body to form a polyurethane resin molded body, and then slicing the polyurethane resin molded body, and which has countless voids formed inside. Here, a polyurethane sheet refers to a polyurethane-based resin containing polyurethane and polyurethane polyurea.

[0145] A urethane sponge can be used for the base layer 412, and commercially available polyurethane sponges can be used as such. Alternatively, the same polyurethane sheet as the abrasive layer 411 may be used as the base layer 412.

[0146] The polyurethane sheet used for the abrasive layer 411 has a thickness of 0.5 to 2 mm, a Shore D hardness of 20.0 to 70.0, and a density of 0.60 to 1.10 g / cm³. ３ Each of these can be set accordingly. By setting the Shore D hardness of the polishing layer 411 within the aforementioned range, the occurrence of scratches can be suppressed.

[0147] The urethane sponge used in the base layer 412 has a thickness of 0.5 to 2 mm, a Shore A hardness of 20.0 to 75.0, and a density of 0.20 to 0.70 g / cm³. ３Each of these can be set accordingly. By setting the Shore A hardness of the base layer 412 within the aforementioned range, the cushioning properties of the polishing pad 401 are improved, and the polishing rate can be increased.

[0148] Furthermore, the storage modulus (at 40°C) of the polishing layer 411 is 55 to 400 MPa, preferably 70 to 130 MPa, and the storage modulus (at 40°C) of the base layer 412 is 1 to 10 MPa, preferably 2 to 8 MPa. It is desirable that the ratio of the storage modulus of the polishing layer 411 to the storage modulus of the base layer 412 be in the range of 2 to 60, preferably 5 to 50. By setting it in this way, it becomes possible to polish the workpiece without damaging the edge shape of the workpiece.

[0149] In the aforementioned polishing pad 401, in order to uniformly polish the workpiece 403 while pressing it with a large pressing force, a concentric airbag A is provided on the holding platen 405 to apply different radial pressures to the workpiece 403.

[0150] As described above, when using a holding platen 405 equipped with multiple airbags A, at the boundary between adjacent airbags A, the pressure from each airbag A is not transmitted to the workpiece 403, and the pressing force at that location is lower than at other locations.

[0151] As a result, the rebound force from the polishing pad 401 due to compression is concentrated in the portion of the workpiece 403 corresponding to the boundary between the airbags A and the other airbags A. This causes the portion to be excessively polished, resulting in the formation of concentric irregularities along the boundary, which is thought to cause the wavy surface.

[0152] In this embodiment, the base material layer 412 of the polishing pad 401 has the following configuration. That is, the surface and / or back surface of the base material layer 412 according to this embodiment are processed to be a height-changing surface 414 with a flat-concave or curved shape.

[0153] As shown in Figure 38, the polishing pad 401 of the tenth embodiment has its surface and / or the height-changing surface 414 on the back side of the base material layer 412 processed into a curved surface shape by profile processing, where the surface on the front side and / or the height-changing surface 414 on the back side of the base material layer 412 consists of a mountain portion M having a height-changing ridge and a valley portion V having a height-changing inclined surface.

[0154] Here, profiling is known as the following processing method. As shown in Figure 39, for example, pressure P is applied with a roller to the required part of a rectangular elastic body shown by the dashed line, and a recessed portion is created in the plane in the M and X directions. In this state, it is sliced ​​with a horizontal plane H, the roller is removed, and the pressure is released.

[0155] As a result, as shown in Figure 40, it is divided into two pieces, with the part that was under pressure returning to its original shape to become the peak M, and the part that was not under pressure becoming the valley V. In practice, the peak M and valley V of the desired size are created by applying pressure with a roller having a set-sized uneven surface.

[0156] In the tenth embodiment shown in Figure 38, the dimension L (Figure 41) connecting the vertex of the peak M and the bottom point of the valley V with a straight line when the peak M and the valley V are viewed from above is processed to be continuous with the same dimension.

[0157] In the tenth embodiment shown in Figure 38, the dimension L (Figure 40) connecting the apex of the peak M and the bottom point of the valley V with a straight line when the peak M and the valley V are viewed from above is shown to be the same. However, this dimension L may be of multiple types and may be processed accordingly.

[0158] A height-changing surface 414, which is a curved surface formed by profile processing, consisting of a peak M having a height-changing ridge and a valley V having a height-changing inclined surface, can also be defined by the area of ​​the valley when the peak and valley are viewed from above. Figure 41 shows a schematic diagram of the peak M having a height-changing ridge and the valley V having a height-changing inclined surface in a side view in Figure 41(a). Figure 41 shows a schematic diagram of the peak M having a height-changing ridge and the valley V having a height-changing inclined surface in a plan view in Figure 41(b). In Figure 41(b), the area of ​​the peak M when viewed from above is shown by S1, and the area of ​​the valley V is shown by S2. Furthermore, the height dimension (d in Figure 40) between the vertex of the peak M and the bottom point of the valley V may be processed to be of multiple types.

[0159] The height dimension d between the peak of the peak M and the bottom of the valley V is not particularly limited, but is preferably 20% to 80% of the thickness of the base layer 412, more preferably 25% to 75%, and even more preferably 30% to 70%. When the height dimension d between the peak of the peak M and the bottom of the valley V is 20% to 80% of the thickness of the base layer 412, the stress when the workpiece 403 is pressed against the polishing pad 401 is more easily distributed, and wavyness is more easily reduced.

[0160] The distance between the vertex of one peak M and the adjacent vertex of another peak M is not particularly limited, but is preferably 2 mm or more and 10 mm or less. By having a distance of 2 mm or more and 10 mm or less between the vertex of one peak M and the adjacent vertex of another peak M, the adhesion between the polishing layer 411 and the base material layer 412 is ensured, while the stress when the workpiece 403 is pressed against the polishing pad 401 is more easily distributed, making it easier to reduce waviness.

[0161] In this embodiment, when the peak portion M and the valley portion V are viewed from above, the area S1 of the peak portion M may be the same or different. Of course, when the peak portion M and the valley portion V are viewed from above, the area S1 of the peak portion M and the area S2 of the valley portion V may be different, the same, or even set to any desired area. Furthermore, the height dimension between the vertex of the peak portion M and the base of the valley portion V may be processed to be of multiple types or a single type.

[0162] In any case, polishing is performed with the area above the polishing layer 12 supported near the peak of the peak M on the height-changing surface 414, allowing for flexible movement in response to the load and dispersing the repulsive force on the workpiece 403. Therefore, it can be inferred that the irregularities generated at the boundary of the airbag A on the workpiece 403 will be smaller than those of conventional polishing pads, leading to a reduction in waviness.

[0163] Figures 42 and 43 are perspective views of a portion of the base material layer 412 as viewed from the front (or back) side according to the 11th embodiment. In this 11th embodiment, the surface on the front side and / or the height-changing surface 414 on the back side of the base material layer 412 is processed to be a bottomed porous surface. In this embodiment, the height-changing surface 414 is processed so that each hole in the bottomed porous surface is continuous. Here, continuous means that the holes are close together and have a width or diameter equal to or the same as the width or diameter of the holes. Therefore, the space between a hole in the height-changing surface 414 and an adjacent hole is flat, but it has a function equivalent to the peak M in the 10th embodiment.

[0164] In this embodiment, the opening shape of the holes in the bottomed porous structure is of several different types. In Figures 42 and 43, the opening shapes are shown as circular and elliptical, but they may also be oval, polygonal, or irregular in shape. Furthermore, the depth of the holes may also be of multiple types.

[0165] The depth of the holes is not particularly limited, but is preferably 20% to 80% of the thickness of the base layer 412, more preferably 25% to 75%, and even more preferably 30% to 70%. When the depth of the holes is 20% to 80% of the thickness of the base layer 412, the stress when the workpiece 403 is pressed against the polishing pad 401 is more easily distributed, making it easier to reduce waviness.

[0166] In this embodiment, since each hole is continuous and the space between a hole and an adjacent hole functions as a ridge M, polishing is performed with the upper part of the polishing layer supported by the space between the holes and the adjacent holes, and it is expected that the pad will move flexibly in response to the load, thereby dispersing the repulsive force on the workpiece 403. For this reason, it is presumed that even at the position corresponding to the boundary of the airbag A on the workpiece 403, the irregularities generated at the boundary of the airbag A will be smaller than those of conventional polishing pads, and it is expected that this will lead to a reduction in waviness.

[0167] The distance between the ridge M formed between one hole and an adjacent hole and the adjacent ridge M is not particularly limited, but is preferably 2 mm to 10 mm. By having a distance of 2 mm to 10 mm between the ridge M and the adjacent ridge M, the adhesion between the polishing layer 411 and the base layer 412 is ensured, while the stress when the workpiece 403 is pressed against the polishing pad 401 is more easily distributed, making it easier to reduce waviness.

[0168] In other words, the polishing pad 401 of the 10th to 11th embodiments is constructed according to the following invention. Firstly, the polishing pad comprises a polishing layer on which a polishing surface for polishing an object to be polished is formed, and a base layer provided on the opposite side of the polishing surface of the polishing layer and held on the polishing platen of a polishing device, characterized in that the surface on the front side and / or the back side of the base layer are processed as a height-changing surface with a flat-concave or curved shape. Secondly, the height-changing surface on the front side and / or the back side of the base layer is processed to be a bottomed-porous surface. Thirdly, the height-changing surface processed to be a bottomed-porous surface is characterized in that each hole in the bottomed-porous surface is processed to be continuous. Fourthly, the opening shape of the holes in the bottomed-porous surface is of several different types. Fifthly, the area shape of the opening of the holes in the bottomed-porous surface is of several different types. Sixthly, the depth of the holes in the bottomed-porous surface is of multiple types. Seventh, the surface and / or back surface of the base material layer is divided into multiple areas, and the depth of the holes in the bottomed porous material is different in each area. Eighth, the surface on the surface side and / or the height-changing surface on the back side of the base material layer is processed by profile processing to form a curved surface in which peaks having height-changing ridges and valleys having height-changing inclined surfaces are connected. Ninth, the dimensions of the lines connecting the peaks and valleys, when viewed from above, are the same and continuous. Tenth, the dimensions of the lines connecting the peaks and valleys, when viewed from above, are processed to be of multiple types. Eleventh, the areas of the peaks are the same or different when viewed from above. Twelfth, the areas of the valleys are the same or different when viewed from above. Thirteenth, the height dimension between the peak of the mountain section and the bottom of the valley section is processed to be of multiple types.The polishing pad according to an embodiment of the present invention comprises a polishing layer having a polishing surface for polishing an object to be polished, and a base layer provided on the opposite side of the polishing surface of the polishing layer and held on the polishing platen of a polishing device. The surface on the front side and / or the back side of the base layer are processed to have a flat-concave or curved shape with varying heights. As a result, the base layer having these varying heights deforms flexibly in response to a load, making it less likely for pressure to concentrate in a specific area, and it is expected that the rebound of the polishing layer that occurs at the boundary of the airbag will be reduced in the base layer. This makes it possible to suppress the occurrence of waviness without significantly changing the polishing characteristics by modifying the material of the polishing layer.

[0169] The polishing pads according to the 12th to 15th embodiments will be described below. In each figure, the same components are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensions of each part in each figure are exaggerated for illustrative purposes, and their ratios differ from those of actual parts. Figure 44 shows a perspective view of a polishing apparatus 502 equipped with a polishing pad 501 according to an embodiment of the present invention, which is used to polish an object to be polished 503 such as a semiconductor substrate. The polishing apparatus 502 includes a polishing platen 504 provided below to support the polishing pad 501, and a holding platen 505 provided above to hold the object to be polished 503.

[0170] The polishing pad 501 and the workpiece 503 are each substantially disc-shaped, with the polishing pad 501 having a larger diameter than the workpiece 503. The upper surface of the polishing pad 501 has a polishing surface that contacts the workpiece 503 to perform polishing. Slurry is supplied to this polishing surface from the slurry supply means 506. The lower surface of the polishing pad 501 is fixed to the polishing platen 504 by double-sided tape or the like.

[0171] As shown in Figures 45 and 46, the holding platen 505 comprises a disc-shaped top ring 505a and a plurality of airbags A arranged concentrically on the lower surface of the top ring 505a, so that the disc-shaped workpiece 503 is held in close contact with the lower surface of the airbags A.

[0172] As shown in Figure 45, the holding platen 505 comprises a disc-shaped top ring 505a, an airbag A consisting of a plurality of concentrically arranged compartments on the lower surface of the top ring 505a, and an annular retainer ring 505b that holds the airbag A and the outer periphery of the workpiece 503. The disc-shaped workpiece 503 is held in close contact with the lower surface of the airbag A inside the retainer ring 505b.

[0173] The polishing platen 504 and the holding platen 505 are each rotated by a driving means (not shown), and the holding platen 505 is further reciprocated radially from the center position of the polishing platen 504. As a result, the workpiece 503 held by the holding platen 505 slides radially along the polishing surface of the rotating polishing pad 501 while rotating.

[0174] The slurry supply means 506 supplies a slurry, in which abrasive particles are mixed in a required liquid, to the polishing surface of the polishing pad 501. This allows the slurry to penetrate between the polishing surface and the workpiece 503, thereby performing so-called chemical mechanical polishing (CMP).

[0175] Figure 45 shows a cross-sectional view of a polishing apparatus 502 and polishing pad 501 according to the twelfth embodiment. Note that the dimensions of each part in each figure are exaggerated for illustrative purposes. The holding platen 505 is equipped with first to sixth airbags A1 to A6 concentrically on the lower surface of the top ring 505a, and each airbag A has a substantially rectangular cross-section, and its flat lower surface is processed to allow it to adhere closely to and hold the surface of the workpiece 503 to be polished.

[0176] As shown in Figure 46, the first to sixth airbags A1 to A6 are arranged concentrically and consist of a circular first airbag A1 located in the center and ring-shaped second to sixth airbags A2 to A6 surrounding the first airbag A1. Each airbag A (A1 to A6) is capable of applying different pressures (P1 to P6) to the workpiece 503 to be polished.

[0177] Furthermore, the pressure applied to the first to sixth airbags A1 to A6 can be adjusted according to the workpiece 503 to be polished and various polishing conditions, and since such a holding plate 505 is known from the aforementioned Patent Document 1, etc., further detailed explanation will be omitted.

[0178] As shown in Figure 45, the polishing pad 501 comprises a polishing layer 511 having a polishing surface that contacts the workpiece 503, a base layer 512 provided on the side of the polishing layer 511 opposite to the polishing surface and held by the polishing platen 504, and an adhesive layer 513 that adheres the polishing layer 511 and the base layer 512. The adhesive layer 513 can be made of a core material made of polyethylene terephthalate (PET) with a pressure-sensitive adhesive such as an acrylic adhesive formed on the front and back surfaces, respectively. There are no particular restrictions on the adhesive layer 513, and it can be arbitrarily selected from various types of double-sided tapes.

[0179] A polyurethane sheet can be used for the polishing layer 511. As such a polyurethane sheet, a foamed polyurethane sheet can be used, which is formed by mixing an isocyanate-terminated prepolymer (hereinafter sometimes simply referred to as prepolymer), a curing agent, and a hollow body to form a polyurethane resin molded body, and then slicing the polyurethane resin molded body, and which has countless voids formed inside. Here, a polyurethane sheet refers to a polyurethane-based resin containing polyurethane and polyurethane polyurea.

[0180] A urethane sponge can be used for the base layer 512, and commercially available polyurethane sponges can be used as such. Alternatively, the same polyurethane sheet as the abrasive layer 511 may be used as the base layer 512.

[0181] The polyurethane sheet used for the abrasive layer 511 has a thickness of 0.5 to 2 mm, a Shore D hardness of 20.0 to 70.0, and a density of 0.60 to 1.10 g / cm³. ３ Each of these can be set accordingly. By setting the Shore D hardness of the polishing layer 511 within the aforementioned range, the occurrence of scratches can be suppressed.

[0182] The urethane sponge used in the base layer 512 has a thickness of 0.5 to 2 mm, a Shore A hardness of 20.0 to 75.0, and a density of 0.20 to 0.70 g / cm³. ３ Each of these can be set accordingly. By setting the Shore A hardness of the base layer 512 within the aforementioned range, the cushioning properties of the polishing pad 501 can be improved, and the polishing rate can be increased.

[0183] Furthermore, the storage modulus (at 40°C) of the polishing layer 511 is 55 to 400 MPa, preferably 70 to 130 MPa, and the storage modulus (at 40°C) of the base layer 512 is 1 to 10 MPa, preferably 2 to 8 MPa. It is desirable that the ratio of the storage modulus of the polishing layer 511 to the storage modulus of the base layer 512 be in the range of 2 to 60, preferably 5 to 50. By setting it in this way, it becomes possible to polish the workpiece without damaging the edge shape of the workpiece.

[0184] In the aforementioned polishing pad 501, in order to uniformly polish the workpiece 503 while pressing it with a large pressing force, a concentric airbag A is provided on the holding platen 505 to apply different radial pressures to the workpiece 503.

[0185] As described above, when using a holding platen 505 equipped with multiple airbags A, the pressure from each airbag A is not transmitted to the workpiece 503 at the boundary between adjacent airbags A, and the pressing force at that location is lower than at other locations. As a result, the rebound force from the polishing pad 501 due to compression is concentrated in the part of the workpiece 503 corresponding to the boundary between airbags A, and this part is excessively polished, causing concentric irregularities to form along the boundary, which is thought to be the cause of the wavy surface.

[0186] In this embodiment, the polishing pad 501 employs the following configuration for the polishing layer 511. Specifically, the surface and / or back surface of the base material layer 512 according to this embodiment are provided with notches 514 in an auxetic pattern.

[0187] Here, an auxetic structure is characterized by the fact that when stress is applied to stretch or compress it, it expands or contracts in a direction perpendicular to the stress, and unlike ordinary materials and structures, it has the characteristic of having a negative Poisson's ratio. Furthermore, auxetics are said to be geometric patterns with numerous periodically placed incisions on a plane, and they have the characteristic of expanding vertically when stretched horizontally.

[0188] The aforementioned Poisson's ratio is ν ｘ = -ε ｘ / ε ｚ ν ｙ = -ε ｙ / ε ｚ It is represented as follows.

[0189] In other words, when a uniaxial stress (stress acting in only one direction) is applied to an object in the z-axis direction, the object's dimensions in the z-axis direction elongate due to its elasticity, generating a longitudinal strain εx. Incidentally, transverse strains εx and ε also occur in the x and y axes perpendicular to the z-axis. This phenomenon is called the Poisson effect. The Poisson ratio is obtained by dividing this transverse strain by the longitudinal strain and multiplying by -1.

[0190] Figure 47 is a plan view of the base material layer 512 as seen from the front (or back) side according to the twelfth embodiment. In this embodiment, as shown in Figure 47(b), three cuts 514 along the line segments extending from each vertex of an equilateral triangle to the centroid of the triangle are considered as one unit. A linear cut section C is formed by arranging a large number of triangles with their vertices facing upwards in the figure. In this way, the cuts 514 are provided along discontinuous cut line segments.

[0191] Figure 48 is a plan view of the twelfth embodiment in which stress is applied to the base layer 512 and the notch C is expanded. In this way, during polishing, the notch C is expected to move to exhibit a closed state and an expanded state, thereby dispersing the repulsive force on the workpiece 503. For this reason, it can be inferred that even at the position corresponding to the boundary position of the airbag A on the workpiece 503, the irregularities generated at the boundary position of the airbag A will be smaller compared to conventional polishing pads, and this is expected to lead to a reduction in waviness.

[0192] The depth of the notch 514 in the base layer 512 is not particularly limited, but is preferably 70% or more of the thickness of the base layer 512, more preferably 80% or more, and even more preferably 90% or more. When the depth of the notch 514 is 70% or more of the thickness of the base layer 512, the stress when the workpiece 503 is pressed against the polishing pad 501 is more easily distributed, and wavy is more easily reduced.

[0193] Figure 49 is a plan view of the base material layer 512 as seen from the front (or back) side according to the 13th embodiment. As shown in Figure 49(b), this 13th embodiment has a shape in which a dashed line H extending in the vertical direction and a dashed line L extending in the horizontal direction are perpendicular to each other at the break point S of each dashed line. The portion of the line segments of dashed line H and dashed line L is a cut line. In this way, the cut 514 is provided along the discontinuous cut line segment.

[0194] Figure 50 is a plan view of the 13th embodiment in which stress is applied to the base layer 512 and the notch C is expanded. In this way, during polishing, the notch is expected to move to exhibit both a closed state and an expanded state, thereby dispersing the repulsive force on the workpiece 503.

[0195] Figure 51 is a plan view of the base material layer 512 as seen from the front (or back) side according to the 14th embodiment. This 14th embodiment has a shape in which two trapezoidal shapes without a top base are joined at the top base side and the resulting sake bottle shape is continuous both vertically and horizontally. Cut lines are formed on the sides of the trapezoidal shapes without a top base, excluding the vertices. That is, the cuts are made along discontinuous cut line segments. The "shape in which two trapezoidal shapes without a top base are joined at the top base side and the resulting sake bottle shape is continuous both vertically and horizontally" can be called a cell region, and a pattern is formed on the front and / or back side of the base material layer 512 in which a large number of cell regions surrounded by the discontinuous cut line segments are arranged.

[0196] Figure 52 is a plan view showing the state in which stress is applied and the notch expands in the base layer 512 in the 14th embodiment. In this way, during polishing, it is expected that the notch will move to exhibit a closed state and an expanded state, thereby dispersing the repulsive force on the workpiece 503.

[0197] Figure 53 is a plan view of the notch 514 as seen from the surface (or back) side of the base layer 512 according to the 15th embodiment. In this 15th embodiment, horizontal dashed lines, in which line segments of a predetermined length are arranged horizontally at predetermined intervals, are arranged vertically at predetermined intervals. Multiple first diagonal dashed lines are arranged diagonally by arranging line segments of a predetermined length at predetermined intervals so as to connect the gaps where the line segments in each horizontal dashed line are interrupted. Multiple second diagonal dashed lines are arranged diagonally by arranging line segments of a predetermined length at predetermined intervals so as to connect the gaps where the line segments in the first diagonal dashed lines are interrupted. The positions of these line segments are defined as the notch 514. In this embodiment as well, it is expected that the notch will move to exhibit a closed state or an open state, thereby dispersing the repulsive force on the workpiece 503.

[0198] Figure 54 is a plan view of the notch 514 as seen from the surface (or back) side of the base layer 512 according to the 16th embodiment. The notch 514 is formed by joining a first V-shaped line, which is formed by joining two line segments from the left and right at a first angle, and a second V-shaped line, which is formed by joining two line segments from the left and right at a second angle, to create a V-shape. A shape is created by arranging these V-shapes horizontally, and multiple rows of these horizontally arranged V-shapes are provided vertically. The notch 514 is provided along this V-shape. The notch 514 forms an auxetic pattern of notches. The V-shaped portion can be called a cell region. In the base layer 512 of this fifth embodiment as well, during polishing, it is expected that the notches will move to exhibit closed and open states, thereby dispersing the repulsive force on the workpiece 503.

[0199] In each of the above embodiments, the cell regions on the front or back surface of the base layer 512 can be the same or different in size (area). That is, cell regions of the same size may be continuous, or cell regions of different sizes (areas) may be continuous. Furthermore, the numerous cell regions may be the same or different in shape. Accordingly, the shape of the notches 514 provided in the cell regions may be the same or different for each cell region.

[0200] Furthermore, the surface and / or back surface of the base material layer 512 may be divided into multiple areas, and the depth of the cuts may be different or the same. The depth of the cuts is preferably 70% or more of the thickness of the base material layer 512, more preferably 80% or more, and even more preferably 90% or more. When the depth of the cuts is 70% or more of the thickness of the base material layer 512, the stress when the workpiece 503 is pressed against the polishing pad 501 is more easily distributed, and waviness is more easily reduced.

[0201] In other words, the polishing pad 501 of the 10th to 11th embodiments is constructed according to the following invention. Firstly, the polishing pad comprises a polishing layer on which a polishing surface for polishing an object to be polished is formed, and a base layer provided on the opposite side of the polishing surface of the polishing layer and held on the polishing platen of a polishing device, wherein the surface and / or back side of the base layer is provided with notches in an auxetic pattern. Secondly, the notches are provided along discontinuous notch lines. Thirdly, the surface and / or back side of the base layer is provided with a pattern in which a large number of cell regions surrounded by the discontinuous notch lines are arranged. Fourthly, the large number of cell regions are of the same or different sizes (areas). Fifthly, the large number of cell regions are of the same or different shapes. Sixthly, the surface and / or back side of the base layer is divided into a plurality of areas, and the depth of the notches is different for each area. The polishing pad according to the above embodiment comprises a polishing layer having a polishing surface for polishing the workpiece, and a base layer provided on the opposite side of the polishing surface of the polishing layer and held on the polishing platen of the polishing device. Since notches in an auxetic pattern are provided on the surface and / or back side of the base layer, the base layer deforms flexibly in response to load due to the movement of these notches, so that pressure is less likely to concentrate on specific parts and it is expected that the rebound of the polishing layer that occurs at the boundary of the airbag can be reduced. As a result, the occurrence of waviness can be suppressed without significantly changing the polishing characteristics by modifying the material of the polishing layer.

[0202] 1 Polishing device 2 Workpiece 3 Polishing pad 4 Polishing platen 5 Holding platen 11 Polishing layer 11a Grooves (recesses) in the surface structure of the polishing surface of the polishing layer 12 Base layer 12a Grooves (recesses) in the adhesive surface of the base layer on the polishing layer side 101 Polishing pad 102 Polishing device 103 Workpiece 104 Polishing platen 105 Holding platen 111 Polishing layer 112 Base layer 113 Concentric grooves on the polishing layer side 114, 116, 117 Concentric grooves on the base layer side Pc Intersection 201 Polishing pad 202 Polishing device 203 Workpiece 204 Polishing platen 205 Holding platen 211 Polishing layer 212 Base layer 214 Circular groove 215 Radial groove 215a Long radial groove 215b Short radial groove 216a Flat portion on the adhesive surface of the base layer 216b Flat portion on the adhesive surface of the polishing layer 216c Flat portion on the holding surface of the base layer M Movement range 301 Polishing pad 302 Polishing device 303 Workpiece to be polished 304 Polishing platen 305 Holding platen 305a Top ring 306 Slurry supply means 311 Polishing layer 312 Base layer 313 Adhesive layer 331 Second groove group 332 First groove group 401 Polishing pad 402 Polishing device 403 Workpiece to be polished 404 Polishing platen 405 Holding platen 405a Top ring 406 Slurry supply means 411 Polishing layer 412 Base layer 413 Adhesive layer 414 Height changing surface 501 Polishing pad 502 Polishing device 503 Workpiece to be polished 504 Polishing platen 505 Holding platen 505a Top ring 506 Slurry supply means 511 Polishing layer 512 Base layer 513 Adhesive layer 514 Cut

Claims

1. A polishing pad comprising a polishing layer having a polishing surface for polishing an object to be polished, and a base layer provided on the side opposite to the polishing surface of the polishing layer, wherein the polishing surface of the polishing layer has at least one surface structure selected from the group consisting of grid grooves, radial grooves, spiral grooves, concentric grooves, and through holes, and the adhesive surface of the base layer on the polishing layer side has at least one surface structure selected from the group consisting of grid grooves, radial grooves, spiral grooves, concentric grooves, and through holes.

2. The polishing pad according to claim 1, characterized in that the surface structure of the adhesive surface of the base material layer on the polishing layer side does not extend to the outer circumference of the base material layer.

3. The polishing pad according to claim 1, characterized in that the surface structure of the adhesive surface of the base material layer on the polishing layer side and the surface structure of the polishing surface of the polishing layer have the same surface pattern.

4. The polishing pad according to claim 3, characterized in that the arrangement of recesses in the surface structure of the polishing surface of the polishing layer is misaligned with the arrangement of recesses in the surface structure of the adhesive surface of the base layer on the polishing layer side.

5. The polishing pad according to claim 1, wherein a polishing layer has a polishing layer side concentric groove formed on the polishing surface of the polishing layer, the base layer side concentric groove formed on at least one surface of the base layer on the polishing layer side adhesive surface, the polishing platen side holding surface, or the base layer side adhesive surface of the polishing layer, and the center of the polishing layer side concentric groove and the center of the base layer side concentric groove are separated so that, in a plan view, multiple intersections are formed in the circular grooves constituting the polishing layer side concentric groove that intersect with the base layer side concentric groove.

6. The polishing pad according to claim 5, characterized in that the distance between the center of the concentric groove on the polishing layer side and the center of the concentric groove on the base material layer side is set to be equal to or greater than one groove pitch of the concentric groove on the base material layer side.

7. The polishing pad according to claim 5, characterized in that the maximum number of intersections formed in the circular grooves of the concentric grooves on the polishing layer side is 4 or more.

8. The polishing pad according to claim 5, characterized in that the groove pitch of the concentric grooves on the polishing layer and the base material layer side is 1.0 mm to 3.5 mm.

9. The polishing pad according to claim 5, characterized in that the polishing layer is made of a polyurethane sheet and has a Shore D hardness of 20.0° to 60.0°.

10. The polishing pad according to claim 5, characterized in that the base material layer is a urethane sponge and has a Shore A hardness of 20.0° to 75.0°.

11. The polishing pad according to claim 5, characterized in that the ratio of the storage modulus of the polishing layer to the storage modulus of the base layer is in the range of 2 to 60.

12. The polishing pad according to claim 5, characterized in that the ends of the circular grooves of the concentric grooves on the base layer side are provided so as not to reach the outer circumference of the base layer or polishing layer.

13. A polishing pad characterized in that a plurality of radial grooves are formed radially on at least one surface of the base material layer on the adhesive surface on the polishing layer side, the polishing layer on the adhesive surface on the base material layer side, or the holding surface of the base material layer on the polishing platen side, and the ends of the radial grooves on the central side of the base material layer or the polishing layer are separated from each other to form a flat portion in the central part of the base material layer or the polishing layer.

14. The polishing pad according to claim 13, characterized in that the outer peripheral end of the radial groove does not reach the outer peripheral of the base material layer or the polishing layer.

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