Polishing pad, polishing method, and method for manufacturing semiconductor

Abstract

The present invention relates to a polishing pad and a polishing method employing said polishing pad, the polishing pad including a polishing layer having a circular polishing surface, wherein: the polishing layer has one or more grooves α, each having a first end portion Eα1 and a second end portion Eα2 closer to the outer circumferential side of the polishing surface than the first end Eα1, each groove α extending from the first end portion Eα1 toward the second end portion Eα2; the first end portion Eα1 of each groove α exists in a region (1) which is in a range of 70.0 to 99.0% of the radius of the polishing surface from the center of the polishing surface; and the second end portion Eα2 of each groove α is not connected to the outer circumference of the polishing layer.

Description

Polishing pad, polishing method, and semiconductor manufacturing method

[0001] The present invention relates to a polishing pad, a polishing method, and a method for manufacturing a semiconductor.

[0002] BACKGROUND ART Chemical mechanical polishing (CMP) has been used in the past to polish substrate materials such as semiconductors and silicon wafers; and glass, which is a material for hard disks, liquid crystal displays, lenses, etc., to a mirror finish; and to flatten irregularities in insulating films, metal films, etc., in the manufacturing process of semiconductor devices. In this method, a polishing material is pressed against a polishing pad while a polishing slurry (hereinafter also simply referred to as slurry) is dropped onto the polishing surface of the polishing pad.

[0003] Polishing pads for CMP have grooves such as spiral grooves, concentric grooves, lattice grooves, and radial grooves formed therein for the purposes of retaining slurry evenly on the polishing surface, discharging polishing debris, and preventing damage due to adsorption of the material to be polished.

[0004] For example, Patent Document 1 discloses a polishing pad including a polishing layer having a circular polishing surface, the polishing surface comprising a central region that is 0 to 10% of the radius from the center of the polishing surface, and a peripheral region that is 90 to 100% of the radius, the polishing layer comprising at least one spiral groove or a concentric groove consisting of a plurality of concentrically arranged annular grooves, arranged from the central region to the peripheral region, and further comprising radial grooves that are at least two linear grooves extending from the central region toward the peripheral region, the centers of the spiral groove, the concentric groove, and the radial groove being present in the central region, the linear grooves having an average length that is 30 to 65% of the radius of the polishing surface, and having a first end in a region that is 5 to 10% of the radius from the center of the radial groove and a second end in a region that is 35 to 70% of the radius of the polishing surface, and a cross-sectional area Sa (mm ２ ) and a cross-sectional area Sb (mm ２ ) and satisfies 0.1≦Sb / Sa<1.0.

[0005] Furthermore, for example, Patent Document 2 discloses a polishing pad including a polishing layer, the polishing layer including at least two concentric grooves, the innermost concentric groove being defined as the first concentric circle and the outermost concentric groove being defined as the second concentric circle, the distance from the center of the polishing layer to the innermost of the first concentric circle being W1, the distance from the outermost of the second concentric circle to the edge of the polishing layer being W3, and the radius of the polishing layer being R, the first polishing region is the inner region of the first concentric circle, the second polishing region is the region where the distance between the first concentric circle and the second concentric circle is W2 = R - W1 - W3, the third polishing region is the region where the distance between the second concentric circle and the edge of the polishing layer is W3, the third polishing region further includes a third groove, the outer end of the third groove is connected to the edge of the polishing layer, and the inner end of the third groove is located inside the second polishing region.

[0006] Furthermore, Patent Document 3 discloses a polishing pad for CMP having a plurality of grooves on its surface, the pad having concentric pad circles (circular grooves) centered on the rotation axis of the rotary pad, the plurality of grooves being substantially perpendicular to a first pad circle, and the deviation of the radial component of the plurality of grooves being substantially greater than the deviation of the circumferential component as the plurality of grooves extend from the center of the pad to the outside of the pad.

[0007] International Publication No. 2023 / 013576 Chinese Patent Application Publication No. 112809550 International Publication No. 2006 / 093670

[0008] In CMP, a polishing pad that can achieve higher polishing speed and polishing accuracy is required. However, according to the investigations of the present inventors, it has been difficult to achieve both a high polishing speed and high polishing uniformity in the region near the outer edge of the polished material (hereinafter also referred to as the "outer edge region").

[0009] The present invention has been made in consideration of the above-mentioned conventional problems, and has as its object to provide a polishing pad that can obtain a high polishing rate in CMP and achieve excellent polishing uniformity in the outer edge region of the workpiece, a polishing method that uses the polishing pad, and a semiconductor manufacturing method that uses the polishing method.

[0010] The present inventors focused on improving the uniformity of slurry distribution in the polishing area and discovered that a polishing pad with specific grooves in a polishing layer can solve the above-mentioned problems, thereby completing the present invention. The present invention relates to the following [1] to

[15] . [1] A polishing pad including a polishing layer with a circular polishing surface, wherein the polishing layer has one or more grooves α each having a first end Eα1 and a second end Eα2 located closer to the outer periphery of the polishing surface than the first end Eα1, the grooves α extending from the first end Eα1 to the second end Eα2, the first end Eα1 of the groove α being located within a region (1) that is 70.0 to 99.0% of the radius of the polishing surface from the center of the polishing surface, and the second end Eα2 of the groove α not connected to the outer periphery of the polishing layer. [2] The polishing pad according to [1] above, wherein the first end Eα1 of the groove α is located within a region (1) that is 70.0 to 95.0% of the radius of the polishing surface from the center of the polishing surface. [3] The polishing pad according to [1] or [2] above, wherein the second end Eα2 of the groove α is located in a region of 85.0 to 99.9% of the radius of the polishing surface from the center of the polishing surface. [4] The polishing pad according to any of [1] to [3] above, wherein the number of grooves α is 2 to 36. [5] The polishing pad according to any of [1] to [4] above, wherein the groove α is linear. [6] The polishing pad according to any of [1] to [5] above, wherein the polishing layer further comprises a reference recess β, and the reference recess β is a spiral, annular, or lattice-shaped reference groove β1, or a reference hole β2 consisting of a plurality of holes. [7] The polishing pad according to [6] above, wherein the polishing layer comprises the reference groove β1, and the groove α intersects with the reference groove β1 at at least one point. [8] The polishing pad according to [6] or [7] above, wherein the groove α has a depth 0.5 to 2.5 times the depth of the reference groove β1.[9] The polishing pad according to any one of [1] to [8] above, wherein the polishing layer further comprises one or more grooves γ each having a first end Eγ1 and a second end Eγ2 located closer to the outer periphery of the polishing surface than the first end Eγ1, the grooves γ extending from the first end Eγ1 to the second end Eγ2, and the first end Eγ1 of the groove γ is located within a region (2) that is less than 70.0% of the radius of the polishing surface from the center of the polishing surface.

[10] The polishing pad according to [9] above, wherein the first end Eα1 of the groove α is located closer to the outer periphery of the polishing surface than the second end Eγ2 of the groove γ.

[11] The polishing pad according to

[10] above, wherein the difference (distance A - distance B) between the center of the polishing surface and the first end Eα1 of the groove α and the distance B from the center of the polishing surface to the second end Eγ2 of the groove γ is 8.0 to 50.0% of the radius of the polishing surface.

[12] The polishing pad according to any one of [9] to

[11] above, wherein the length of the groove α is 5.0 to 100.0% of the length of the groove γ.

[13] The polishing pad according to any one of [9] to

[12] above, wherein at least one of the groove α or the groove γ is linear.

[14] A polishing method for polishing a workpiece using the polishing pad according to any one of [1] to

[13] above, wherein the groove α is positioned below a retainer ring that surrounds the workpiece.

[15] A method for manufacturing a semiconductor, comprising the step of polishing a semiconductor material by the polishing method according to

[14] above.

[0011] According to the present invention, it is possible to provide a polishing pad that can achieve a high polishing rate in CMP and achieve excellent polishing uniformity in the outer edge region of the workpiece, a polishing method that uses the polishing pad, and a semiconductor manufacturing method that uses the polishing method.

[0012] 9A is a schematic plan view of a polishing pad 10, which is one embodiment of the polishing pad of the present invention. FIG. 9B is a schematic plan view illustrating the region of the polishing surface of the polishing pad 10. FIG. 9C is a schematic cross-sectional view illustrating the shape of a cross section in a direction perpendicular to the length direction of a groove. FIG. 9D is a schematic cross-sectional view illustrating the shape of a cross section in a direction perpendicular to the length direction of a groove. FIG. 9E is a schematic plan view of a polishing pad 20, which is one embodiment of the polishing pad of the present invention. FIG. 9F is a schematic plan view illustrating the region of the polishing surface of the polishing pad 20. FIG. 9G is a schematic cross-sectional view of the polishing pad 10 in the thickness direction. FIG. 9H is an explanatory view illustrating CMP. FIG. 9A is a schematic plan view illustrating the position of a polishing head in CMP, and FIG. 9B is a schematic cross-sectional view of the polishing head and the polishing layer.

[0013] The following describes an example of an embodiment of the present invention. However, the embodiments described below are merely examples for embodying the technical concept of the present invention, and the present invention is not limited to the following description. The present invention also includes any embodiment or combination of any of the features described herein. In this specification, preferred specifications can be selected arbitrarily, and combinations of preferred specifications are considered more preferable. In this specification, the expression "XX to YY" means "XX or more and YY or less." In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60."

[0014] [Polishing Pad] The polishing pad of this embodiment will be described below with reference to the drawings. FIG. 1 is a schematic plan view illustrating a polishing pad 10, which is an example of a polishing pad of this embodiment. In the polishing pad 10, the polishing surface of the polishing layer 1 is circular. The polishing layer 1 has 16 grooves α, each having a first end Eα1 and a second end Eα2 that is located closer to the outer periphery of the polishing surface than the first end Eα1, extending from the first end Eα1 toward the second end Eα2. The polishing layer 1 also has one spiral groove H, with the center G of the polishing surface as the spiral center. The 16 grooves α are linear and are formed radially at equal intervals in the outer periphery of the polishing surface, with the center G of the polishing surface as the radial center. In the polishing pad 10, the portions where the grooves α and spiral grooves H are not formed become land areas that contact and polish the polished surface of the workpiece.

[0015] 2 is an explanatory diagram illustrating regions on the polishing surface of the polishing pad 10. In the polishing pad 10, the region indicated by diagonal lines, which is 70.0 to 99.0% of the radius R of the polishing surface from the center G of the polishing surface, is region (1). The region from the center G of the polishing surface to the radius R of the polishing surface is a region where the distance from the center of the polishing surface is R × 70.0% or more, and the region from the center G of the polishing surface to the radius R of the polishing surface is a region where the distance from the center of the polishing surface is R × 99.0% or less. The first end Eα1 and second end Eα2 of the 16 grooves α are located within region (1), and the second end Eα2 is not connected to the outer periphery of the polishing layer 1.

[0016] The polishing layer provided in the polishing pad of this embodiment will be described in detail below.

[0017] <Polishing layer> As described above, the polishing layer provided in the polishing pad of this embodiment is a groove having a first end Eα1 and a second end Eα2 that is located closer to the outer periphery of the polishing surface than the first end Eα1, and has one or more grooves α extending from the first end Eα1 toward the second end Eα2.

[0018] (Groove α) In the polishing pad of this embodiment, the first end Eα1 of the groove α is located within a region (1) that is 70.0 to 99.0% of the radius of the polishing surface from the center of the polishing surface. The presence of the first end Eα1 of the groove α within region (1) prevents the dischargeability of the slurry in the polishing region from becoming too high, improving the fluidity of the slurry in the polishing region while maintaining a good polishing rate, thereby improving the polishing uniformity in the outer edge region. The region in which the first end Eα1 of the groove α is located is not particularly limited, but is preferably in the range of 70.0 to 95.0%, more preferably 75.0 to 94.0%, and even more preferably 80.0 to 93.0% of the radius of the polishing surface from the center of the polishing surface. When the region in which the first end Eα1 of the groove α is located is within the above range, better polishing rates and polishing uniformity in the outer edge region tend to be easily obtained.

[0019] In the polishing pad of this embodiment, the second end Eα2 of the groove α is not connected to the outer periphery of the polishing layer. Since the second end Eα2 of the groove α is not connected to the outer periphery of the polishing layer, the dischargeability of the slurry in the polishing region is not too high, and the fluidity of the slurry in the polishing region is improved while maintaining a good polishing rate, thereby improving the polishing uniformity in the outer peripheral region. The region in which the second end Eα2 of the groove α exists is not particularly limited, but is preferably in the range of 85.0 to 99.9%, more preferably 86.0 to 99.5%, and even more preferably 94.0 to 99.0% of the radius of the polishing surface from the center of the polishing surface. When the region in which the second end Eα2 of the groove α exists is in the above range, a better polishing rate and polishing uniformity in the outer peripheral region tend to be easily obtained.

[0020] The length of the groove α is not particularly limited, but is preferably 9 to 100 mm, more preferably 20 to 80 mm, and even more preferably 25 to 70 mm. When the length of the groove α is equal to or greater than the above-mentioned lower limit, the supply and discharge of slurry to the polishing region is improved, and better polishing uniformity in the outer edge region tends to be easily obtained. Furthermore, when the length of the groove α is equal to or less than the above-mentioned upper limit, the discharge of slurry does not become too high, and a better polishing rate tends to be easily obtained. In this specification, the "length" of the groove means the length from one end to the other end along the longest axis of the groove.

[0021] The number of grooves α in the polishing layer is 1 or more, preferably 2 to 36, more preferably 4 to 26, and even more preferably 6 to 20. When the number of grooves α is equal to or greater than the above-mentioned lower limit, the supply and discharge of slurry to the polishing region is improved, and better polishing uniformity in the outer edge region tends to be easily obtained. On the other hand, when the number of grooves α is equal to or less than the above-mentioned upper limit, the discharge of slurry is not too high, and a better polishing rate tends to be easily obtained.

[0022] From the viewpoint of polishing uniformity in the outer edge region, the grooves α are preferably formed radially with the center of the polishing surface as the radial center, and more preferably formed radially at equal intervals in the outer circumferential direction of the polishing surface.

[0023] The shape of the grooves α may be linear or curved. Examples of curved shapes include arc shapes. The polishing layer may have both linear and curved grooves α. Among these, linear grooves α are preferred because they can easily prevent slurry from pooling in the polishing region. In this specification, the groove shape refers to the shape of the polishing layer when viewed from above.

[0024] The cross-sectional shape of the groove α may be, for example, a quadrilateral shape such as a rectangle, a square, a trapezoid, or an inverted trapezoid; a triangular shape (V-shape), a semicircular shape, a semi-elliptical shape, or the like. Among these, a quadrilateral shape is preferred from the viewpoint of processability and slurry fluidity. In this specification, the cross-sectional shape of the groove means the shape of the cross section in a direction perpendicular to the longitudinal direction of the groove.

[0025] 3(a) to 3(c) show schematic cross-sectional views of a groove cut perpendicular to its length. To suppress the generation of burrs during polishing, the groove α preferably has a cross-sectional shape that is inclined so that the groove tapers inversely toward the opening. Specifically, as shown in FIG. 3(b), the groove may have a so-called Y-shape, in which two corners forming a rectangular groove located on the polishing surface are chamfered and tapered at a predetermined angle S. Alternatively, as shown in FIG. 3(c), the groove may have an inverted trapezoidal cross section, in which the hypotenuse is inclined at a predetermined angle S relative to the two corners forming the base angle. In this embodiment, the Y-shaped groove is considered to be included in the concept of a "quadrilateral shape." The angle S of inclination is not particularly limited, but is preferably 20 degrees or more and less than 90 degrees, more preferably 25 to 80 degrees, and even more preferably 30 to 75 degrees. The inclination formed on the groove wall may be formed on both sides of the groove wall, or only on one side of the groove wall. When the inclination is formed on the groove walls on both sides of the groove, the inclination angles S may or may not be the same. Examples of combinations in which the groove wall angles on both sides of the groove are not the same include 90° / 60°, 80° / 60°, 80° / 50°, 70° / 50°, 70° / 40°, 60° / 40°, and 60° / 30°. When the groove walls on both sides of the groove are present on the inner and outer periphery of the polishing pad, the angle of the groove wall on the inner periphery of the polishing pad may be larger than the angle of the groove wall on the outer periphery, or the angle of the groove wall on the inner periphery of the polishing pad may be smaller than the angle of the groove wall on the outer periphery. Furthermore, when the groove walls on both sides of the groove are present on the rotation direction side and the opposite side of the polishing pad, the angle of the groove wall on the rotation direction side may be larger than the angle of the groove wall on the opposite side, or the angle of the groove wall on the rotation direction side may be smaller than the angle of the groove wall on the opposite side. When the inclination angle is within the above range, the generation of burrs that tend to occur at the corners of the groove during polishing is easily suppressed, and a decrease in the polishing rate, a decrease in polishing uniformity, etc. are easily suppressed.

[0026] The groove width of the groove α is not particularly limited, but is preferably 0.1 to 10 mm, more preferably 0.13 to 5 mm, and even more preferably 0.15 to 3 mm. When the groove width of the groove α is within the above range, the area of ​​the groove α and the land area are well balanced, which tends to facilitate obtaining a better polishing rate and polishing uniformity in the outer edge region. Herein, the groove width in this specification refers to the width of the cross-section of the groove when cut in a direction perpendicular to the longitudinal direction, as indicated by W in FIG. 3( a). However, the groove width is defined as follows depending on the cross-sectional shape of the groove. When the cross-sectional shape is rectangular or square, it is defined as the width at the polishing surface. Furthermore, when the cross-sectional shape is trapezoidal or inverted trapezoidal, it is defined as the average width of the lower base. Furthermore, when a chamfered tapered portion is formed, such as in a Y-shape, it is defined as the width of the groove cross-section on the polishing surface as if the tapered portion were not formed. Furthermore, when the cross-sectional shape is triangular, semicircular, or semi-elliptical, it is defined as the width at half the depth.

[0027] The depth of the groove α is not particularly limited, but is preferably 0.3 to 3.0 mm, more preferably 0.5 to 2.5 mm, and even more preferably 0.8 to 2.0 mm. When the depth of the groove α is equal to or greater than the above-mentioned lower limit, accumulation of slurry in the groove α is suppressed, and better polishing uniformity in the outer edge region tends to be easily obtained. Furthermore, when the depth of the groove α is equal to or less than the above-mentioned upper limit, the influence of wear on the polishing surface can be reduced, and even when the polishing pad is continuously used, the polishing rate and polishing uniformity in the outer edge region tend to be easily maintained. In this specification, the groove depth means the average depth of the deepest part of the groove.

[0028] (Reference Recess β) The polishing layer preferably further includes a reference recess β. The reference recess β is preferably a spiral, annular, or lattice-shaped reference groove β1, or a reference hole β2 consisting of a plurality of holes.

[0029] 1, as one embodiment of the reference recess β, a spiral groove H having 10 turns and a substantially uniform groove pitch P is formed from the spiral center coincident with the center G of the polishing surface of the polishing layer 1. A spiral with a uniform groove pitch is also called an Archimedes spiral.

[0030] From the viewpoint of spreading the slurry evenly over the polishing area, the reference recess β is preferably formed over an area of ​​5.0% or less to 90.0% or more of the radius of the polishing surface from the center of the polishing surface, more preferably over an area of ​​4.5% or less to 95.0% or more, and even more preferably over an area of ​​4.0% or less to 100.0%.

[0031] (Reference groove β1) The reference groove β1 is a spiral groove, an annular groove, or a lattice groove. Among these, a spiral groove or annular groove is preferred from the viewpoint of the polishing rate and the polishing uniformity of the outer edge region. As the annular groove, a concentric groove is preferred. When the reference groove β1 is a spiral groove, the position of the start point of the spiral groove is not particularly limited, but is preferably within a range of 5.0% or less, more preferably 4.5% or less, and even more preferably 4.0% or less of the radius of the polishing surface from the center of the polishing surface, and the position of the end point of the spiral groove is preferably within a range of 90.0% or more, more preferably 95.0% or more of the radius of the polishing surface from the center of the polishing surface, and it is even more preferred that it reaches the outer periphery of the polishing layer. When the reference recess β is a concentric groove, the area through which the annular groove closest to the center of the polishing surface passes is not particularly limited, but is preferably in the range of 5.0% or less, more preferably 4.5% or less, and even more preferably 4.0% or less of the radius of the polishing surface from the center of the polishing surface, and the area through which the annular groove farthest from the center of the polishing surface passes is preferably in the range of 90.0% or more, more preferably 95.0% or more of the radius of the polishing surface from the center of the polishing surface.

[0032] The cross-sectional shape of the reference groove β1 is not particularly limited, and may be the same as the cross-sectional shape of the groove α. Among these, a rectangular shape is preferred from the viewpoints of processability, slurry retention, and supply stability. From the same viewpoint as in the case of the groove α, the cross-sectional shape of the reference groove β1 also preferably has an inclined cross section so that the groove is reverse tapered toward the opening. The preferred aspect of the inclined cross section is the same as in the case of the groove α.

[0033] The groove width of the reference groove β1 is not particularly limited, but is preferably 0.1 to 4 mm, more preferably 0.13 to 2 mm, and even more preferably 0.15 to 1 mm. When the groove width of the reference groove β1 is within the above range, the area of ​​the reference groove β1 and the land area are well balanced, and a better polishing rate and polishing uniformity in the outer edge region tend to be easily obtained.

[0034] The depth of the reference groove β1 is not particularly limited, but is preferably 0.2 to 3.0 mm, more preferably 0.4 to 2.5 mm, and even more preferably 0.8 to 2.0 mm. When the depth of the reference groove β1 is equal to or less than the upper limit, the supply of slurry to the polishing area and the deformation resistance of the polishing pad tend to be improved. Furthermore, when the depth of the reference groove β1 is equal to or greater than the lower limit, the amount of slurry retained in the polishing area becomes sufficient, and a better polishing rate tends to be obtained.

[0035] When the polishing layer has a reference groove β1, the depth of the groove α is not particularly limited, but is preferably 0.5 to 2.5 times, more preferably 0.7 to 1.8 times, and even more preferably 0.9 to 1.4 times the depth of the reference groove β1. When the depth of the groove α relative to the depth of the reference groove β1 is equal to or greater than the above-mentioned lower limit, the influence of wear on the polishing surface can be reduced, and even when the polishing pad is used continuously, the polishing rate and polishing uniformity in the outer edge region tend to be easily maintained. Furthermore, when the depth of the groove α relative to the depth of the reference groove β1 is equal to or less than the above-mentioned upper limit, slurry accumulation in the groove α is suppressed, and better polishing uniformity in the outer edge region tends to be easily obtained.

[0036] In the spiral groove, concentric groove, or grid-like groove serving as the reference groove β1, the groove pitch P, which is the distance between adjacent grooves, is not particularly limited, but is preferably 1 to 15 mm, more preferably 1.5 to 12 mm, and even more preferably 2 to 10 mm. When the groove pitch P is equal to or greater than the lower limit, the amount of slurry supplied to the polishing region becomes sufficient, and a better polishing rate tends to be obtained. Furthermore, when the groove pitch P is equal to or less than the upper limit, the balance between the areas of the reference groove β1 and the land area becomes good, and a better polishing rate and polishing uniformity tend to be obtained. Figure 4 shows a schematic cross-sectional view of a groove cut perpendicular to its longitudinal direction. In this specification, the groove pitch P refers to the distance between adjacent grooves, as indicated by P in Figure 4.

[0037] The spiral groove serving as the reference groove β1 may be a single spiral groove, or may be two or more spiral grooves in which a plurality of spiral grooves are arranged in parallel. Specifically, the number of parallel spiral grooves is preferably 1 to 16, and more preferably 1 to 10.

[0038] The spiral groove or concentric groove serving as the reference groove β1 preferably has its center coincident with the center of the polishing surface from the viewpoint of easily obtaining uniform fluidity of the slurry, whereas the spiral groove or concentric groove may be eccentric and not coincident with the center of the polishing surface from the viewpoint of easily suppressing transfer of the shape of each groove to the polishing surface of the workpiece caused by excessive polishing along each groove.

[0039] The polishing layer preferably includes a reference groove β1, and the groove α intersects with the reference groove β1 at at least one point. In the polishing surface of the polishing layer 1 of the polishing pad 10 shown in Figure 1, the 16 grooves α each form an intersection with the spiral groove H. The intersection of the groove α and the reference groove β1 improves the supply and discharge of slurry to the polishing area, as well as improving the fluidity of the slurry in the polishing area, thereby further improving the uniformity of the slurry distribution in the polishing area.

[0040] The reference holes β2 are preferably formed in a predetermined pattern, such as a circle, an ellipse, or a polygon, when viewed from above the polishing layer. The holes are preferably recessed and do not penetrate the polishing layer. The depth of the holes constituting the reference holes β2 is not particularly limited, but is preferably less than or equal to the thickness of the polishing layer, and is preferably 0.2 to 5.0 mm, more preferably 0.3 to 3.0 mm, and even more preferably 0.4 to 2.5 mm.

[0041] 5 is a plan view schematic diagram illustrating a polishing pad 20, an example of a polishing pad according to this embodiment. The polishing layer 1 of the polishing pad 20 includes the same grooves α and spiral grooves H as those of the polishing pad 10 shown in FIG. 1 , and further includes 16 grooves γ each having a first end Eγ1 and a second end Eγ2 located closer to the outer periphery of the polishing surface than the first end Eγ1, the grooves extending from the first end Eγ1 to the second end Eγ2. The 16 grooves γ are linear and are formed radially at equal intervals in the outer periphery of the polishing surface, with the center G of the polishing surface as the radial center. The grooves γ and grooves α are each formed on the same straight line connecting the center G of the polishing surface and the outer periphery of the polishing surface.

[0042] 6 is an explanatory diagram illustrating regions on the polishing surface of polishing pad 20. In polishing pad 20, the circular region indicated by solid diagonal lines and ranging from 70.0 to 99.0% of the radius from the center G of the polishing surface is region (1), and the region indicated by dashed diagonal lines and ranging from the center G of the circular polishing surface to less than 70.0% of the radius is region (2). The first end Eγ1 and second end Eγ2 of the 16 grooves γ are located within region (2).

[0043] (Groove γ) In the polishing pad of this embodiment, the first end Eγ1 of the groove γ is located within a region (2) that is less than 70.0% of the radius of the polishing surface from the center of the polishing surface. The presence of the first end Eγ1 of the groove γ within region (2) tends to ensure a sufficient amount of slurry is supplied to the polishing region, making it easier to achieve a better polishing rate. The region in which the first end Eγ1 of the groove γ is located is not particularly limited, but is preferably in the range of 0.0 to 20.0%, more preferably 2.0 to 15.0%, and even more preferably 3.0 to 10.0% of the radius of the polishing surface from the center of the polishing surface. When the region in which the first end Eγ1 of the groove γ is located is within the above range, slurry dropped onto the polishing surface tends to penetrate the groove γ at an appropriate timing, making it easier to uniformly distribute the slurry in the polishing region. Note that when the polishing layer has two or more grooves γ, the first end Eγ1 of the groove γ refers to the end of the groove γ closest to the center of the polishing surface. Furthermore, the region where the first end Eγ1 exists is 0% of the radius of the polishing surface from the center of the polishing surface, meaning that the position of the first end Eγ1 is the center of the polishing surface. Furthermore, in this embodiment, when the position of the first end Eγ1 is 0% of the radius of the polishing surface from the center of the polishing surface, the grooves γ may be connected to each other at the center of the polishing surface. Even in such a case, the connected grooves γ are not counted as one groove, but are counted as a number corresponding to the number of second ends.

[0044] The region where the second end Eγ2 of the groove γ exists is not particularly limited, but is preferably in the range of 30.0 to 80.0%, more preferably 40.0 to 75.0%, and even more preferably 45.0 to 70.0% of the radius of the polishing surface from the center of the polishing surface. The presence of the second end Eγ2 of the groove γ in this region tends to ensure that the slurry that has entered the groove γ is appropriately sent to the polishing region, and the dischargeability of the slurry is not too high, making it easier to achieve a better polishing rate. Note that when the polishing layer has two or more grooves γ, the second end Eγ2 of the groove γ refers to the end of the groove γ that is farthest from the center of the polishing surface.

[0045] It is preferable that the first end Eα1 of the groove α be located closer to the outer periphery of the polishing surface than the second end Eγ2 of the groove γ. This tends to prevent excessive discharge of slurry from the polishing region, and to facilitate improved polishing uniformity in the outer peripheral region while maintaining a good polishing rate. From the same perspective, the difference (distance A - distance B) between the distance A from the center of the polishing surface to the first end Eα1 of the groove α and the distance B from the center of the polishing surface to the second end Eγ2 of the groove γ is not particularly limited, but is preferably 8.0 to 50.0%, more preferably 10.0 to 45.0%, and even more preferably 15.0 to 40.0% of the radius of the polishing surface.

[0046] The number of grooves γ in the polishing layer is not particularly limited, but is preferably at least 1, more preferably 2 to 36, even more preferably 4 to 26, and even more preferably 6 to 20. When the number of grooves γ is within the above range, the balance between the slurry supplyability and dischargeability is excellent, and the slurry retention force in the polishing region tends to be improved. The number of grooves α and the number of grooves γ in the polishing layer may be the same or different.

[0047] The shape of the grooves γ may be linear or curved. The polishing layer may also have both linear and curved grooves γ. Among these, linear grooves γ are preferred because they facilitate suppressing accumulation of slurry in the polishing region. When the polishing pad of this embodiment has grooves α and γ, it is preferred that at least one of the grooves α and γ be linear.

[0048] From the viewpoint of polishing uniformity in the outer edge region, the grooves γ are preferably formed radially from the center of the polishing surface as the radial center, and more preferably formed radially at equal intervals in the circumferential direction of the polishing surface. When the grooves γ and the grooves α are formed radially from the center of the polishing surface as the radial center, the grooves γ and the grooves α may be formed on the same straight line connecting the center of the polishing surface and the periphery of the polishing surface, or may be formed on different straight lines, but from the viewpoint of ease of processing the grooves, they are preferably formed on the same straight line.

[0049] The cross-sectional shape of the groove γ is not particularly limited, and may be the same as the cross-sectional shape of the groove α. Among these, a rectangular shape is preferred from the viewpoints of processability, slurry retention, and supply stability. From the same viewpoint as in the case of the groove α, the cross-sectional shape of the groove γ also preferably has an inclined cross section so that the groove is reverse tapered toward the opening. The preferred aspect of the inclined cross section is the same as in the case of the groove α.

[0050] The groove width of the groove γ is not particularly limited, but is preferably 0.1 to 10 mm, more preferably 0.13 to 5 mm, and even more preferably 0.15 to 3 mm. When the groove width of the groove γ is within the above range, the balance between the areas of the groove γ and the land area becomes good, and better polishing rate and polishing uniformity tend to be easily obtained.

[0051] The depth of the groove γ is not particularly limited, but is preferably 0.2 to 3.0 mm, more preferably 0.4 to 2.5 mm, and even more preferably 0.8 to 2.0 mm. When the depth of the groove γ is equal to or less than the upper limit, the supply of slurry to the polishing region and the deformation resistance of the polishing pad tend to be improved. Furthermore, when the depth of the groove γ is equal to or greater than the lower limit, the amount of slurry retained in the polishing region becomes sufficient, and a better polishing rate tends to be obtained. The depth of the groove γ may be constant or may vary along the groove. The point at which the depth of the groove γ changes may be, for example, in a region of 2 to 50% of the length of the groove γ, starting from the first end Eγ1. When the depth of the groove γ becomes shallower from the second end Eγ2 toward the first end Eγ1, processing accuracy tends to be improved.

[0052] When the polishing layer of the polishing pad of this embodiment has a reference groove β1 and a groove γ, the reference groove β1 and the groove γ preferably intersect at least one point. The intersection of the groove γ and the reference groove β1 makes it easier to quickly supply and retain the slurry that has entered the groove γ in the polishing area. In the polishing surface of the polishing layer 1 of the polishing pad 20 shown in Figure 5, each of the 16 grooves γ forms an intersection with the spiral groove H.

[0053] The length of the groove γ is not particularly limited, but is preferably 100 to 280 mm, more preferably 120 to 250 mm, and even more preferably 150 to 230 mm. When the length of the groove γ is equal to or greater than the above-mentioned lower limit, the supply of slurry to the polishing region tends to be improved. On the other hand, when the length of the groove γ is equal to or less than the above-mentioned upper limit, the discharge of the slurry does not become too high, and a better polishing rate tends to be obtained.

[0054] The length of the groove α is not particularly limited, but is preferably 5.0 to 100.0%, more preferably 8.0 to 70.0%, and even more preferably 10.0 to 65.0% of the length of the groove γ. When the relationship between the lengths of the groove α and the groove γ is within the above range, there is a tendency for the polishing uniformity in the outer edge region to be easily improved while maintaining the polishing rate.

[0055] (Shape of the Polishing Layer, etc.) The diameter of the circular polishing surface can be the diameter of the polishing surface of a typical circular polishing pad used in CMP. For example, the diameter of the circular polishing surface is preferably 500 to 780 mm. Therefore, the radius of the circular polishing surface is preferably 250 to 390 mm, for example.

[0056] The thickness of the polishing layer is not particularly limited, but is preferably 0.4 to 5 mm, more preferably 0.6 to 4.5 mm, and even more preferably 1.2 to 2.5 mm. When the thickness of the polishing layer is within the above range, productivity and handleability are improved, and the stability of polishing performance tends to be improved.

[0057] The polishing layer preferably has a non-foamed structure (non-porous). A polishing layer with a non-foamed structure (non-porous) can maintain high hardness, exhibit better planarization properties, and is less likely to cause scratches because the abrasive grains in the slurry do not aggregate or adhere in the pores. In addition, the wear rate of the polishing layer is lower than that of a polishing layer with a foamed structure, which can extend the life of the polishing pad.

[0058] (Hardness of the Polishing Layer) The D hardness of the polishing layer is not particularly limited, but is preferably 45 to 90, more preferably 50 to 88, even more preferably 55 to 87, and even more preferably 60 to 86. When the D hardness of the polishing layer is within the above range, polishing uniformity tends to be further improved. The D hardness can be measured in accordance with JIS K 7311:1995, and more specifically, can be measured by the method described in the Examples.

[0059] (Density of the Polishing Layer) The density of the polishing layer is not particularly limited, but is preferably 1.0 g / cm ３ More preferably, 1.1 g / cm ３ More preferably, 1.2 g / cm ３ When the density of the polishing layer is equal to or greater than the above lower limit, a better polishing rate and polishing uniformity tend to be easily obtained. The upper limit of the density of the polishing layer is not particularly limited, but from the viewpoint of ease of manufacture, it is preferred that the upper limit be 1.4 g / cm ３ or less, 1.3 g / cm ３ The density of the polishing layer may be less than or equal to the external dimensions (cm ３ The weight (g) can be calculated based on the weight of the sample.

[0060] Next, the material for forming the polishing layer provided in the polishing pad of this embodiment and the method for producing the same will be described.

[0061] <Material for forming the polishing layer> As the material for forming the polishing layer, synthetic or natural polymer materials conventionally used in the manufacture of polishing layers of polishing pads can be used. Examples of polymer materials include polyurethane, polyethylene, polypropylene, polybutadiene, ethylene-vinyl acetate copolymer, butyral resin, polystyrene, polyvinyl chloride, acrylic resin, epoxy resin, polyester, polyamide, etc. These may be used alone or in combination of two or more. Among these, polyurethane is preferred from the viewpoint of easily obtaining a polishing layer that is excellent in flatness and less susceptible to scratches. Below, polyurethane used as a material for forming the polishing layer will be described in detail as a representative example.

[0062] Polyurethane is obtained by reacting polyurethane raw materials including a polymeric diol, an organic diisocyanate, and a chain extender.

[0063] Specific examples of polymer diols include polyether diols such as polyethylene glycol and polytetramethylene glycol; polyester diols such as poly(nonamethylene adipate)diol, poly(2-methyl-1,8-octamethylene adipate)diol and poly(3-methyl-1,5-pentamethylene adipate)diol; and polycarbonate diols such as poly(hexamethylene carbonate)diol and poly(3-methyl-1,5-pentamethylene carbonate)diol. These may be used alone or in combination of two or more. Of these, polyether diols are preferred, and polytetramethylene glycol is more preferred.

[0064] Specific examples of organic diisocyanates include aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-bis(isocyanatomethyl)cyclohexane; and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 1,5-naphthylene diisocyanate. These may be used alone or in combination of two or more. Among these, aromatic diisocyanates are preferred, and 4,4'-diphenylmethane diisocyanate is more preferred, from the viewpoint of providing excellent abrasion resistance to the polishing layer.

[0065] Examples of chain extenders include low-molecular-weight compounds having a molecular weight of 350 or less and containing two or more active hydrogen atoms in the molecule that can react with isocyanate groups. Specific examples of chain extenders include diols such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-bis(β-hydroxyethoxy)benzene, 1,9-nonanediol, cis-2-butene-1,4-diol, and spiroglycol; and diamines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, hydrazine, xylylenediamine, isophoronediamine, and piperazine. These may be used alone or in combination of two or more. Among these, at least one selected from 1,4-butanediol, cis-2-butene-1,4-diol, 1,5-pentanediol and 1,9-nonanediol is preferred.

[0066] The blending ratio of each component of the polyurethane raw material is adjusted appropriately taking into consideration the properties to be imparted to the polishing layer, but for example, the amount of isocyanate groups contained in the blended organic diisocyanate is preferably 0.95 to 1.3 mol, more preferably 0.96 to 1.1 mol, and even more preferably 0.97 to 1.05 mol per mol of active hydrogen atoms contained in the polymer diol and chain extender. When this blending ratio is equal to or greater than the lower limit, the mechanical strength and abrasion resistance of the polyurethane tend to be improved. On the other hand, when this blending ratio is equal to or less than the upper limit, the productivity and storage stability of the polyurethane tend to be improved.

[0067] The polyurethane is preferably thermoplastic polyurethane from the viewpoint that it can obtain a polishing layer having high hardness and excellent flattening properties.The term "thermoplastic" refers to the property that it can be melted and molded by a heating process such as extrusion molding, injection molding, calender molding, 3D printer molding, etc.Thermoplastic polyurethane can be obtained, for example, by using the polyurethane raw material and polymerizing it through a urethanization reaction using a known prepolymer method or one-shot method.More specifically, the thermoplastic polyurethane is preferably produced by melt-polymerizing the polyurethane raw material while melt-mixing it in the substantial absence of solvent, and from the viewpoint of productivity, it is more preferable to use a multi-screw extruder to melt-mix the polyurethane raw material while continuously melt-polymerizing it.

[0068] <Method for manufacturing the polishing layer> The polishing layer can be manufactured, for example, by a method of forming a polymer material composition obtained by blending the above-mentioned polymer material with additives for the polishing layer, etc. as necessary, into a sheet. The content of the polymer material in the polymer material composition is not particularly limited, but is preferably 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 99% by mass or more.

[0069] Examples of methods for forming the polymeric material composition into a sheet include a method in which the polymeric material composition is melt-extruded into a sheet using an extruder such as a single-screw extruder or a twin-screw extruder equipped with a T-die. Alternatively, the polymeric material composition may be molded into a block shape, and the block-shaped molded product may be sliced ​​into a sheet.

[0070] The polymeric material composition formed into a sheet by the above method is adjusted to a desired thickness by grinding or the like, and then formed into a desired shape by cutting, punching, milling, etc., to obtain a polishing layer sheet. One surface of the polishing layer sheet is then used as a polishing surface, and the various grooves described above are provided on this polishing surface to obtain the polishing layer used in the polishing pad of this embodiment.

[0071] Examples of methods for forming grooves include a method of cutting one surface of the polishing layer sheet to form grooves; a method of stamping a heated mold, metal wire, or the like onto one surface of the polishing layer sheet and contacting it to melt or volatilize a polymer to form grooves by transfer processing; a method of laser processing one surface of the polishing layer sheet to decompose or volatilize a polymer to form grooves; a method of molding a polishing layer sheet with a polishing surface having grooves using a mold in which convex portions for forming grooves are previously formed; etc. Among these, from the viewpoint of excellent productivity, the cutting method or the transfer processing method is preferred, and from the viewpoint of excellent processing precision, the cutting method is more preferred.

[0072] The polishing layer produced as described above may be used as a single-layer polishing pad as it is, or may be used as a polishing pad having a laminated structure of two or more layers in which other layers such as a cushion layer, a support layer, etc. are laminated on the surface opposite the polishing surface of the polishing layer. When the polishing pad has a laminated structure, a cushion layer, a support layer, etc. are laminated on the surface opposite the polishing surface of the polishing layer via a pressure-sensitive adhesive, adhesive, etc.

[0073] 7 is a partial cross-sectional schematic diagram of a cross section in the thickness direction for explaining the layer structure of polishing pad 10. Polishing pad 10 has a laminated structure in which a cushion layer 7 is bonded via an adhesive layer 6 to the surface opposite to the polishing surface F of polishing layer 1.

[0074] <Cushion layer> The polishing pad may have a cushion layer from the viewpoint of improving the polishing uniformity over the entire surface. The cushion layer is preferably a layer having a hardness lower than that of the polishing layer. When the hardness of the cushion layer is lower than that of the polishing layer, the hard polishing layer follows the local unevenness of the polished surface, and the cushion layer follows the warpage and undulation of the polished material as a whole, so that polishing with an excellent balance between global flatness (a state in which the large periodic unevenness of the wafer substrate is reduced) and local flatness (a state in which the local unevenness is reduced) is possible.

[0075] Examples of materials that can be used for the cushion layer include composites in which nonwoven fabric is impregnated with polyurethane (e.g., "Suba 400" (manufactured by Nitta Haas Inc.)); rubbers such as natural rubber, nitrile rubber, polybutadiene rubber, and silicone rubber; thermoplastic elastomers such as polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and fluorine-based thermoplastic elastomers; foamed plastics; polyurethanes, etc. Among these, polyurethanes having a foamed structure are preferred from the viewpoint of easily achieving the flexibility desired for the cushion layer.

[0076] The thickness of the cushion layer is not particularly limited, but is preferably 0.5 to 5 mm. When the thickness of the cushion layer is equal to or greater than the above lower limit, the effect of following up the overall warp, waviness, etc. of the polished surface becomes sufficient, and global flatness tends to be better. Furthermore, when the thickness of the cushion layer is equal to or less than the above upper limit, the entire polishing pad has an appropriate hardness, and polishing stability tends to be better.

[0077] The preferred thickness of the polishing pad of this embodiment is the same as the preferred thickness of the polishing layer described above if the polishing pad of this embodiment does not have a cushion layer. Furthermore, the preferred thickness of the polishing pad of this embodiment is 1 to 10 mm if the polishing pad of this embodiment has a cushion layer.

[0078] [Polishing Method] The polishing method of this embodiment is a polishing method for polishing a workpiece using the polishing pad of this embodiment, in which the groove α is disposed under a retainer ring that surrounds the workpiece. An embodiment in which CMP is performed using the polishing pad of this embodiment will be described.

[0079] 8 shows a schematic diagram of a CMP apparatus 100. The CMP apparatus 100 includes a circular rotating platen 101, a slurry supply nozzle 102, a polishing head 103 that holds a material to be polished, and a pad conditioner 104. A polishing pad 10 is attached to the surface of the rotating platen 101 with a double-sided adhesive sheet or the like.

[0080] In the CMP apparatus 100, the rotating platen 101 is rotated, for example, in the direction indicated by the arrow (clockwise direction) by a motor (not shown). The polishing head 103 is rotated, for example, in the direction indicated by the arrow (clockwise direction) by a motor (not shown) while pressing the surface to be polished of the workpiece 50 against the polishing surface of the polishing pad 10. The pad conditioner 104 rotates, for example, in the direction indicated by the arrow (clockwise direction). When the diameter of the pad conditioner 104 is smaller than the diameter of the workpiece 50, the pad conditioner 104 is oscillated in the radial direction of the rotating platen 101 to provide a surface roughness suitable for polishing over the entire area of ​​the polishing pad that comes into contact with the workpiece 50.

[0081] When an unused polishing pad is used, a conditioning process called break-in is usually performed prior to polishing a workpiece, in which the polishing surface of the polishing pad is finely roughened to form a roughness suitable for polishing. Specifically, the surface of the polishing pad 10 is conditioned by pressing a CMP pad conditioner 104 against the surface of the polishing pad 10, which is fixed to a rotating platen 101 and rotated, while water is flowing over the surface. As the pad conditioner, for example, a pad conditioner in which diamond particles are fixed to the surface of a carrier by nickel electrodeposition or the like is used.

[0082] In the polishing method of this embodiment, the grooves α of the polishing pad of this embodiment are positioned below the retaining ring, which improves the supply and discharge of slurry inside the retaining ring and increases the uniformity of the distribution of slurry in the polishing area, thereby improving the polishing uniformity in the outer edge area.

[0083] 9(a) shows a schematic plan view of the polishing pad 20 and the polishing head 103, and FIG. 9(b) shows a schematic cross-sectional view taken along the line II' in FIG. 9(a). As shown in FIG. 9(b), the polishing head 103 is composed of, for example, a head main body 105, a retainer ring 106 that surrounds the outer periphery of the workpiece 50, an elastic film 107 that presses against the upper surface of the workpiece 50, and an air chamber 108 surrounded by the elastic film 107, the retainer ring 106, and the head main body 105. The retainer ring 106 surrounds the outer periphery of the workpiece 50 to prevent the workpiece 50 from jumping out, and also presses against the polishing surface of the polishing pad 20, thereby flattening the polishing surface of the polishing pad 20 that polishes the workpiece 50.

[0084] 9(b), the groove α disposed below the retaining ring 106 has a first end Eα1 located in an inner region of the retaining ring 106 and a second end Eα2 of the groove α located in an outer region of the retaining ring 106. The above-described positional relationship between the groove α and the retaining ring improves the supply and discharge of slurry inside the retaining ring, which tends to improve polishing uniformity in the outer peripheral region. From the viewpoint of achieving the above-described positional relationship between the groove α and the retaining ring, it is preferable that the length of the groove α be longer than the width Wr of the retaining ring 106 (the radial distance between the inner and outer peripheral surfaces).

[0085] 9(b), when the polishing layer has a groove γ, the groove γ is preferably disposed below the retaining ring 106, and it is more preferable that the groove γ disposed below the retaining ring 106 has its first end Eγ1 located in the outer region of the retaining ring 106 and its second end Eγ2 located in the inner region of the retaining ring. The above-described positional relationship between the groove γ and the retaining ring improves the supply and discharge of slurry inside the retaining ring, which tends to improve polishing uniformity in the outer peripheral region. From the viewpoint of achieving the above-described positional relationship between the groove γ and the retaining ring, the length of the groove γ is preferably longer than the width Wr of the retaining ring 106 (the radial distance between the inner and outer peripheral surfaces).

[0086] After the break-in is complete, polishing of the surface of the workpiece begins. During polishing, a slurry is supplied from a slurry supply nozzle onto the surface of the rotating polishing pad. The slurry contains, for example, a liquid medium such as water or oil; an abrasive such as silica, alumina, cerium oxide, zirconium oxide, or silicon carbide; a base, an acid, a surfactant, an oxidizing agent, a reducing agent, or a chelating agent. Furthermore, when performing CMP, a lubricating oil, a coolant, or the like may be used in combination with the slurry, if necessary.

[0087] The workpiece is then pressed against the polishing pad, which has the slurry evenly spread over the polishing surface of the polishing layer. The polishing process continues until a desired flatness is achieved. The polishing quality can be affected by adjusting the pressing force applied during polishing and the speed of the relative movement between the rotating platen and the holder.

[0088] The polishing conditions are not particularly limited, but for efficient polishing, the rotation speed of each of the rotating platen and holder is preferably low, at 300 rpm or less, and the pressure applied to the workpiece is preferably 150 kPa or less to prevent scratches after polishing. During polishing, it is preferable to continuously supply slurry to the polishing surface using a pump or the like. The amount of slurry supplied is not particularly limited, but it is preferable to supply it so that the polishing surface is always covered with slurry.

[0089] After polishing, the workpiece is preferably thoroughly washed with running water and then dried using a spin dryer or the like to remove water droplets adhering to the workpiece. By polishing the workpiece with the slurry in this manner, a smooth surface can be obtained over the entire surface. The above-mentioned CMP can be suitably used for polishing various semiconductor materials such as silicon wafers.

[0090] The polishing method of this embodiment is preferably used for polishing in the manufacturing processes of various semiconductor devices, MEMS (Micro Electro Mechanical Systems), etc. Examples of materials to be polished include semiconductor substrates such as silicon, silicon carbide, gallium nitride, gallium arsenide, zinc oxide, sapphire, germanium, and diamond; insulating films such as silicon oxide films, silicon nitride films, and low-k films formed on semiconductor substrates; wiring materials such as copper, aluminum, and tungsten; glass, quartz, optical substrates, and hard disks. Among these, the polishing pad of this embodiment is preferably used for polishing insulating films, wiring materials, etc. formed on semiconductor substrates.

[0091] [Method for manufacturing a semiconductor] The method for manufacturing a semiconductor of this embodiment is a method for manufacturing a semiconductor, which includes polishing a semiconductor material by the polishing method of this embodiment. The polishing method of this embodiment has been described above. In the method for manufacturing a semiconductor of this embodiment, examples of the semiconductor material to be polished by the polishing method of this embodiment include the semiconductor substrate, insulating film formed on the semiconductor substrate, wiring material, etc., described in the section "Polishing method of this embodiment." The semiconductor material polished by the polishing method of this embodiment is then cleaned and can be processed into a semiconductor by a known semiconductor manufacturing process.

[0092] The present invention will be described in more detail below with reference to examples, although the scope of the present invention is not limited to these examples in any way.

[0093] [Production Example 1] Polytetramethylene glycol (abbreviation: PTMG) having a number-average molecular weight of 850, polyethylene glycol (abbreviation: PEG) having a number-average molecular weight of 600, 1,4-butanediol (abbreviation: BD), and 4,4'-diphenylmethane diisocyanate (abbreviation: MDI) were blended in a mass ratio of PTMG:PEG:BD:MDI of 24.6:11.6:13.8:50.0, and the mixture was continuously fed to a coaxially rotating twin-screw extruder using a metering pump to continuously melt-polymerize a thermoplastic polyurethane. The polymerized thermoplastic polyurethane melt was then continuously extruded into water in the form of strands and then shredded using a pelletizer to obtain pellets. The pellets were dehumidified and dried at 70°C for 20 hours, then fed to a single-screw extruder and extruded through a T-die to form a sheet. The surface of the obtained sheet was ground to obtain a uniform sheet with a thickness of 2.0 mm, and then cut into a circular shape with a diameter of 740 mm to obtain a non-foamed sheet for abrasive layer. The D hardness of the sheet for abrasive layer measured at a temperature of 25°C in accordance with JIS K 7311:1995 was 62.

[0094] [Production of Polishing Pad] Examples 1 to 20, Comparative Examples 1 to 4 Grooves having a pattern of the shape shown in Table 1 were formed by cutting on the polishing surface, which was one side of the sheet for polishing layer obtained in Production Example 1. In Examples 1 to 6, 9 to 20 and Comparative Examples 1 to 4, the positions of the ends of all grooves γ were as shown in Table 1 for the first end Eγ1 and the second end Eγ2. In Example 7, of the eight grooves γ, the position of the first end of one groove γ was 0%, the positions of the first end of the ends of seven grooves γ were 5.2%, and the positions of the second end of all eight grooves γ were 51.6%. In Example 8, there were eight grooves γ, and grooves γ with a first end position of 0% and grooves γ with a first end position of 5.2% were alternately arranged, and the positions of the second end of all eight grooves were 51.6%. In Examples 1 to 20 and Comparative Examples 1 to 4, grooves α and γ were both formed radially, with the center of the polishing surface as the radial center, at equal intervals in the circumferential direction of the polishing surface. When grooves γ and α were linear, they were formed on the same straight line connecting the center of the polishing surface and the periphery of the polishing surface. Furthermore, arc-shaped grooves γ and α were formed on the same arc connecting the center of the polishing surface and the periphery of the polishing surface. Next, a cushion layer was attached to the back side of the polishing layer opposite the polishing surface with a double-sided adhesive sheet to prepare a multi-layer polishing pad. As the cushion layer, "Poron H48" manufactured by Inoac Corporation, a 0.8 mm thick polyurethane foam sheet, was used.

[0095] The groove width of the groove formed in each example was measured based on a scanning electron microscope (SEM) image of 200 times the cross section.Specifically, the cross section of the groove of each polishing layer was photographed evenly at 18 positions, the groove width of each image was measured, and the average value thereof was obtained.In addition, the groove pitch P of the reference groove β1 was measured by using a scale magnifier to measure 8 positions that were evenly selected from the area that contacts the silicon wafer on the polishing surface, and the average was taken as the groove pitch P.In addition, the depth of each groove was measured by using a depth gauge "E-DP2J" manufactured by Nakamura Manufacturing Co., Ltd. at 8 positions that were evenly selected from the area that contacts the silicon wafer, and the average of the measured values ​​was obtained.

[0096] [Evaluation] The polishing characteristics of the polishing pad obtained in each example were evaluated by the following evaluation method.

[0097] (Method for evaluating the polishing rate) The polishing pad obtained in each example was mounted on a polishing apparatus "FREX-300" manufactured by Ebara Corporation. Then, a slurry prepared by diluting "HS-8005" manufactured by Resonac Corporation 10 times was prepared, and a 12-inch diameter silicon wafer having a silicon oxide film with a film thickness of 2,000 nm on the surface was polished for 60 seconds while supplying the slurry to the polishing surface of the polishing pad at a rate of 200 mL / min under the conditions of a platen rotation speed of 100 rpm, a head rotation speed of 99 rpm, and a polishing pressure of 30.0 kPa. When using a polishing pad having a groove α, the groove α was positioned below the retainer ring attached to the polishing head, and the central end of the groove α (first end Eα1) was located in the inner region of the retainer ring, and the outer peripheral end of the groove α (second end Eα2) was located in the outer region of the retainer ring. Similarly, when using a polishing pad having a groove γ, polishing was performed with the groove γ located below the retainer ring attached to the polishing head, with the central end of the groove γ (first end Eγ1) located in the outer region of the retainer ring, and the outer peripheral end of the groove γ (second end Eγ2) located in the inner region of the retainer ring. Then, using a pad conditioner (A.L.M.T. Corporation diamond dresser (diamond grit #100 blocky, base diameter 19 cm)), the surface of the polishing pad was conditioned for 30 seconds while flowing pure water at a rate of 150 mL / min under the conditions of a dresser rotation speed of 70 rpm, a polishing pad rotation speed of 100 rpm, and a dresser load of 20 N. Then, another silicon wafer was polished again, and conditioning was performed for another 30 seconds. Then, after 60 seconds of polishing, the polishing pad was conditioned for another 30 seconds. Then, another silicon wafer was polished again, and conditioning was performed for another 30 seconds. Ten silicon wafers were polished in this manner. The thickness of the silicon oxide film on the tenth polished silicon wafer was measured at 49 points on the wafer before and after polishing, and the polishing rate (nm / min) at each point was determined. Specifically, the average of the polishing rates at the 49 points was taken as the polishing rate.

[0098] (Method for evaluating polishing uniformity) Under the conditions described in the method for evaluating the polishing rate, the silicon wafer was polished when the groove depth of the groove α of the polishing layer (however, when the groove α was not present and the reference groove β1 was present, the reference groove β1) was reduced by 50%, and the thickness of the silicon oxide film before and after polishing was measured at 87 points on the wafer surface (edge ​​exclusion 3 mm), and the polishing rate (nm / min) at each point was determined. Then, the average value and standard deviation 1σ of the polishing rates at the 87 points were calculated, and the coefficient of variation (unit: %) was calculated from the average value and standard deviation 1σ. A smaller coefficient of variation indicates better polishing uniformity.

[0099] (Method for evaluating polishing uniformity in outer edge region) Under the conditions described in the method for evaluating the polishing rate, the silicon wafer was polished when the groove depth of the groove α of the polishing layer (however, when the groove α was not present and the reference groove β1 was present, the reference groove β1) was reduced by 50%, and the thickness of the silicon oxide film before and after polishing was measured at 20 points in the outer edge region 10 mm from the outside of the wafer, and the polishing rate (nm / min) at each point was determined. The average value and standard deviation 1σ of the polishing rates at the 20 points were then calculated, and the coefficient of variation (unit: %) was calculated from the average value and standard deviation 1σ. A smaller coefficient of variation indicates better polishing uniformity in the outer edge region.

[0100]

[0101] As is clear from the results in Table 1, the polishing pads of Examples 1 to 20 of this embodiment achieved a high level of both polishing rate and polishing uniformity in the outer edge region. On the other hand, the polishing pads of Comparative Examples 1 to 4 were inferior in at least one of the polishing rate and polishing uniformity in the outer edge region.

[0102] REFERENCE SIGNS LIST 1 Polishing layer 6 Adhesive layer 7 Cushion layer 10, 20 Polishing pad 50 Material to be polished 60 Slurry 100 CMP apparatus 101 Rotary surface plate 102 Slurry supply nozzle 103 Polishing head 104 Pad conditioner 105 Head body 106 Retainer ring 107 Elastic membrane 108 Air chamber α: Groove α γ: Groove γ H: Spiral groove Eα1 First end of groove α Eα2 Second end of groove α Eγ1 First end of groove γ Eγ2 Second end of groove γ F Polishing surface G Center of polishing surface P Pitch R Radius of polishing surface S Angle W Groove width Wr Width of retainer ring

Claims

1. A polishing pad including a polishing layer having a circular polishing surface, wherein the polishing layer has one or more grooves α each having a first end Eα1 and a second end Eα2 located closer to the outer periphery of the polishing surface than the first end Eα1, the grooves α extending from the first end Eα1 toward the second end Eα2, the first end Eα1 of the groove α being located within a region (1) that is in the range of 70.0 to 99.0% of the radius of the polishing surface from the center of the polishing surface, and the second end Eα2 of the groove α not connected to the outer periphery of the polishing layer.

2. The polishing pad according to claim 1, wherein the first end Eα1 of the groove α is present in an area that is 70.0 to 95.0% of the radius of the polishing surface from the center of the polishing surface.

3. The polishing pad according to claim 1 or 2, wherein the second end Eα2 of the groove α is present in a region that is 85.0 to 99.9% of the radius of the polishing surface from the center of the polishing surface.

4. The polishing pad according to any one of claims 1 to 3, wherein the number of grooves α is 2 to 36.

5. The polishing pad according to any one of claims 1 to 4, wherein the groove α is linear.

6. A polishing pad according to any one of claims 1 to 5, wherein the polishing layer further comprises a reference recess β, the reference recess β being a spiral, annular or lattice-shaped reference groove β1, or a reference hole β2 consisting of a plurality of holes.

7. The polishing pad according to claim 6, wherein the polishing layer includes the reference groove β1, and the groove α intersects with the reference groove β1 at at least one point.

8. The polishing pad according to claim 6 or 7, wherein the groove α has a depth that is 0.5 to 2.5 times the depth of the reference groove β1.

9. The polishing pad according to any one of claims 1 to 8, wherein the polishing layer further comprises one or more grooves γ having a first end Eγ1 and a second end Eγ2 located closer to the outer periphery of the polishing surface than the first end Eγ1, the grooves γ extending from the first end Eγ1 toward the second end Eγ2, and the first end Eγ1 of the groove γ is present within a region (2) that is within a range of less than 70.0% of the radius of the polishing surface from the center of the polishing surface.

10. The polishing pad according to claim 9, wherein a first end Eα1 of said groove α is located closer to the outer periphery of said polishing surface than a second end Eγ2 of said groove γ.

11. The polishing pad according to claim 10, wherein the difference [distance A - distance B] between the distance A from the center of the polishing surface to the first end Eα1 of the groove α and the distance B from the center of the polishing surface to the second end Eγ2 of the groove γ is 8.0 to 50.0% of the radius of the polishing surface.

12. The polishing pad according to any one of claims 9 to 11, wherein the length of said groove α is 5.0 to 100.0% of the length of said groove γ.

13. The polishing pad according to any one of claims 9 to 12, wherein at least one of the grooves α and the grooves γ is linear.

14. A polishing method for polishing a workpiece using the polishing pad according to any one of claims 1 to 13, wherein the groove α is disposed under a retainer ring surrounding the workpiece.

15. A method for manufacturing a semiconductor, comprising the step of polishing a semiconductor material by the polishing method according to claim 14.

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