Polishing Pad

Abstract

To provide a polishing pad capable of preventing residence of slurry or polishing dusts on a transparent end point detecting window, and preventing accuracy deterioration of end point detection in polishing processing by the end point detecting window.SOLUTION: A polishing pad 3 has a polishing layer 3C comprising an end point detecting window 3B through which inspection light L1 can pass. The polishing surface 3A of the polishing pad has a plurality of concentric circular annular grooves 3Aa. A top face 3Ba of the end point detecting window 3B is lower than the polishing surface 3A, and the top face thereof is a recess 3Ca. A discharge groove 3E in a radial direction is formed, the discharge groove extending from the top face 3Ba of the end point detecting window 3B and the recess 3Ca to a peripheral edge of the polishing surface 3A. During polishing processing, even if slurry or processing dusts enter the top face 3Ba or recess 3Ca of the end point detecting window 3B, through the discharge groove 3E, the slurry or processing dusts are discharged outward of the polishing surface 3A. Therefore, residence of the slurry or polishing dusts on the top face 3Ba on the end point detecting window 3B can be prevented.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a polishing pad, and more particularly to a polishing pad having a transparent end point detection window for detecting the end point of a polishing process and an exhaust groove formed on the polishing surface to prevent a decrease in the detection accuracy of the end point detection window. [Background technology]

[0002] Conventionally, polishing pads that are provided with a transparent end point detection window for detecting the end point of polishing and have discharge grooves on the polishing surface for discharging slurry and polishing waste are well known (for example, Patent Documents 1 and 2). In the polishing pad of Patent Document 1, one surface (upper surface) of the end point detection window is located at a position lower than the bottom of the discharge groove formed in the polishing surface. On the other hand, in the polishing pad of Patent Document 2, a concave surface is formed on the upper surface of the end point detection window, and a discharge groove is formed on the concave surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2013-517146 [Patent Document 2] JP 2016-182667 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the polishing pad of Patent Document 1, one surface (top surface) of the end point detection window is located lower than the polishing surface, so there is a risk that slurry and polishing debris will remain in the end point detection window during polishing, thereby reducing the accuracy of end point detection by the end point detection window. On the other hand, the polishing pad of Patent Document 2 has a concave surface formed on the upper surface of the end point detection window, and a discharge groove is formed on this concave surface, so that the amount of transmission of inspection light differs between the discharge groove and other parts, resulting in a problem of reduced accuracy in end point detection by the end point detection window. Furthermore, when the inspection light is passed through a portion other than the discharge groove, the end point detection window must be made large, and the end point detection window may affect the polishing performance. [Means for solving the problem]

[0005] In view of the above, the present invention provides a polishing pad including a polishing layer having a polishing surface for polishing an object to be polished, and a transparent end point detection window provided in the polishing layer for detecting an end point during polishing, the polishing pad comprising: a surface of the end point detection window facing the polishing surface is formed to be lower than the polishing surface, and a recess is formed between the end point detection window and the polishing surface; Furthermore, at least one discharge groove is formed in the polishing surface, the discharge groove communicating with the recessed portion and the outer peripheral edge of the polishing surface, During polishing, the slurry and polishing waste are discharged from the recess to the outside of the polishing surface through the discharge groove. It has become like this, A plurality of annular grooves are formed at concentric positions on the polishing surface, The discharge groove is provided so as to intersect with the annular groove, a surface of the end point detection window facing the polishing surface is lower than a bottom of the annular groove; Furthermore, the bottom of the discharge groove is at the same height as or lower than the bottom of the annular groove, and is higher than one surface of the end point detection window on the polishing surface side. The present invention is characterized by the following: Effect of the Invention

[0006] According to this configuration, since it is possible to prevent slurry or polishing debris from remaining in the end point detection window, the degree of transmission of the inspection light when it passes through the end point detection window is not changed, and therefore it is possible to prevent a decrease in the accuracy of end point detection. Also, since the surface of the end point detection window that faces the polishing surface is formed to be lower in height than the polishing surface, it is possible to minimize the effect of the end point detection window on polishing. [Brief description of the drawings]

[0007] [Figure 1] 1 is a perspective view of a polishing apparatus showing an embodiment of the present invention; [Diagram 2] FIG. 2 is a longitudinal sectional view of the main part of FIG. [Diagram 3]FIG. 2 is a perspective view of a main part of the polishing surface of FIG. 1. [Figure 4] FIG. 2 is a plan view of a main part of the polishing surface of FIG. 1. [Diagram 5] 2A to 2C are diagrams showing a manufacturing process for the polishing pad of FIG. 1. [Figure 6] FIG. 11 is a plan view of the main part showing a second embodiment of the present invention. [Figure 7] FIG. 11 is a plan view of the main part showing a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1 and 2, reference numeral 1 denotes a polishing apparatus that polishes a thin plate-like object to be polished 2 (e.g., a semiconductor wafer) with a polishing pad 3. When polishing the object to be polished 2, the polishing apparatus 1 irradiates an inspection light L1 toward a surface 2A of the object to be polished 2, thereby making it possible to detect the progress of the polishing and the end point of the polishing. The polishing apparatus 1 is equipped with a polishing platen 4 located on the lower side and having a polishing pad 3 fixed on its upper surface, a holding platen 5 located on the upper side and holding the workpiece 2 to be polished on its lower surface, a slurry supply mechanism 6 that supplies slurry S (polishing liquid) between the workpiece 2 to be polished and the polishing pad 3, and a detection mechanism 7 that uses an inspection light L1 to detect the progress of polishing of the workpiece 2 and the end point of the processing. The object 2 to be polished by the polishing apparatus 1 is an optical material, a silicon wafer, a glass substrate for liquid crystal, a semiconductor substrate, and a plate-like object such as glass, metal, ceramic, etc. As the slurry S to be supplied by the slurry supply mechanism 6, a suitable conventionally known material can be used depending on the object 2 to be polished and the required processing accuracy. The polishing platen 4 and the holding platen 5 are each substantially disk-shaped and are adapted to rotate in the direction of the arrow by a drive mechanism (not shown). The holding platen 5 is also provided so as to be movable up and down. When polishing the object 2, the holding platen 5 presses the polished surface 2A (lower surface) of the object 2 against the polishing surface 3A of the polishing pad 3 at a set pressure while they are rotated relative to each other, and a slurry S is supplied from a slurry supply mechanism 6 between the polished surface 2A of the object 2 and the polishing surface 3A of the polishing pad 3. A plurality of annular grooves 3Aa are formed at equal pitches in the radial direction concentrically around the center (center of rotation) of the polishing pad 3 on the polishing surface 3A of the polishing pad 3. These annular grooves 3Aa serve as slurry holding grooves for holding the slurry S, and the slurry S discharged from the slurry supply mechanism 6 flows into these annular grooves 3Aa and is supplied to the entire polishing surface 3A (see FIGS. 2 to 4).

[0009] Incidentally, when polishing the workpiece 2, it is necessary to detect the progress of the polishing of the workpiece 2 and the end point of the polishing. Therefore, the polishing device 1 is provided with a detection mechanism 7 that irradiates an inspection light L1 from below toward above and detects the progress of the polishing and the end point of the polishing based on the reflected light L2 from the polished surface 2A of the workpiece 2. At a predetermined position of the polishing pad 3, a transparent window 3B for detecting an end point is provided, which transmits the inspection light L1 and also transmits reflected light L2 from the surface 2A of the workpiece 2 to be polished. The polishing pad 3 includes a disk-shaped polishing layer 3C located on the upper side, and a disk-shaped support layer 3D (cushion layer) attached to the lower surface of the polishing layer 3C with an adhesive or double-sided tape. A transparent end point detection window 3B is provided at a predetermined position of the polishing layer 3C, and a through hole 3Da is drilled at the position of the support layer 3D below the window 3B to allow the inspection light L1 and the reflected light from the polished object 2 to pass through. The flat upper surface 3Ba of the end-point detection window 3B is slightly lower than the polishing surface 3A, which is the upper surface of the polishing layer 3C. Specifically, the upper surface 3Ba is located lower than the bottom of the annular groove 3Aa and is about 0.9 mm lower than the polishing surface 3A, resulting in a circular recess 3Ca above the upper surface 3Ba. As described above, a plurality of annular grooves 3Aa are formed concentrically on the polishing surface 3A, and some of these annular grooves 3Aa intersect with the recesses 3Ca located adjacent to and above the end point detection window 3B. That is, as shown in Figures 3 and 4, the plurality of annular grooves 3Aa open on the inner peripheral surface of the recesses 3Ca, and the annular grooves 3Aa and the recesses 3Ca communicate with each other. On the other hand, the lower surface 3Bb of the end point detection window 3B and the lower surface of the polishing layer 3C are flush with each other, and the upper surface of the support layer 3D is adhered to the lower surface of the polishing layer 3C with an adhesive or double-sided tape. The polishing pad 3, which is made up of the polishing layer 3C and the support layer 3D integrated vertically, has its lower surface (the lower surface of the support layer 3D) fixed to the upper surface 4A of the polishing platen 4 with an adhesive or double-sided tape. The polishing table 4 is provided with a light-emitting unit 7A that irradiates inspection light L1 upward and a light-receiving unit 7B that receives reflected light from the polished object 2, below the end-point detection window 3B of the polishing pad 3 and the through-hole 3Da of the support layer 3D. The detection mechanism 7 includes the light-emitting unit 7A and the light-receiving unit 7B, as well as a control unit 7C that controls their operation and detects the progress of polishing during the polishing process and the end point where the process ends. During the polishing process on the workpiece 2, the inspection light L1 is emitted upward from the light emitting unit 7A of the detection mechanism 7, and the inspection light L1 passes through the transparent end point detection window 3B and is irradiated onto the polished surface 2A of the workpiece 2. Then, the inspection light L1 is reflected downward by the polished surface 2A of the workpiece 2, and the reflected light L2 passes through the transparent end point detection window 3B and is detected by the light receiving unit 7B. The reflected light L2 detected by the light receiving unit 7B is transmitted to the control unit 7C. As the polishing of the workpiece 2 progresses and the polishing surface 2A of the workpiece 2 is gradually polished, the intensity of the reflected light L2 detected by the light receiving unit 7B changes. When the intensity of the reflected light L2 detected by the light receiving unit 7B reaches a preregistered intensity, the control unit 7C determines that the polishing surface 2A has reached the end point of polishing, and stops the polishing. Then, the drive mechanism is stopped, so that the rotation of the polishing platen 4 and the holding platen 5 stops, and the supply of the slurry S from the slurry supply mechanism 6 is also stopped. In this way, the end point of polishing can be detected by using the inspection light L1 of the detection mechanism 7 when the workpiece 2 is polished. Note that the configuration of the detection mechanism 7 using such inspection light L1 is already known.

[0010] As shown in Figures 3 and 4, the polishing pad 3 of this embodiment is characterized in that a radial discharge groove 3E is formed on the polishing surface 3A of the polishing layer 3C, extending from the upper surface 3Ba of the end point detection window 3B and the position of the recess 3Ca to the outer peripheral edge of the polishing surface 3A. The end point detection window 3B is formed in a disk shape from a transparent material that transmits the inspection light L1 and the reflected light L2, and this end point detection window 3B fits snugly into a through hole formed at a predetermined position in the polishing layer 3C. The diameter of the end point detection window 3B is set to 9 mm, and the axial dimension (vertical dimension) is shorter than the thickness of the polishing layer 3C. The material of the end point detection window 3B can be an elastic resin such as polyurethane. The end point detection window 3B needs to be structured to avoid foaming that would interfere with the inspection light L1 and the reflected light L2. More specifically, an elastic resin such as polyurethane that does not have voids formed therein is preferable. In this embodiment, the end point detection window 3B is circular, but it may be of various other shapes, such as a rectangle, a square, a polygon, an ellipse, etc. Furthermore, it is sufficient that at least one end point detection window 3B is provided. The height difference between the polishing surface 3A and the upper surface 3Ba of the end point detection window 3B (the depth of the recess 3Ca) is set to about 0.9 mm. Furthermore, the width of each annular groove 3Aa is set to 0.4 mm, and the pitch between adjacent annular grooves 3Aa is set to 2.8 mm. The depth of each annular groove 3Aa is set to 0.6 mm, which allows the slurry or the like to flow from the annular groove 3Aa into the recess 3Ca. The discharge groove 3E is formed linearly in the radial direction of the polishing layer 3C, and the outer end of the discharge groove 3E opens to the outer periphery (outer periphery) of the polishing layer 3C (not shown), and the inner end of the discharge groove 3E opens to the inner periphery of the recess 3Ca. The discharge groove 3E also intersects with the multiple annular grooves 3Aa formed on the polishing surface 3A, and is in communication with them. The depth of the discharge groove 3E is set to 0.8 mm, and the bottom of the discharge groove 3E is higher than the upper surface 3Ba of the end point detection window 3B, and is located at the same position as or lower than the bottom of the annular groove 3Aa. This allows the slurry, etc. to be maintained in a constant amount on the upper surface 3Ba of the end point detection window 3B until it is discharged from the discharge groove 3E, and prevents the intensity of the inspection light L1 and the reflected light L2 from decreasing due to the flow of the slurry, etc., and thus prevents the accuracy of the end point detection by the detection mechanism 7 from decreasing. A plurality of annular grooves 3Aa also intersect with the discharge groove 3E adjacent to the upper surface 3Ba of the end point detection window 3B, so that the plurality of annular grooves 3Aa and the discharge groove 3E are in communication with each other (see FIGS. 2 to 4).

[0011] In this manner, the polishing pad 3 of this embodiment has radial discharge grooves 3E formed on the polishing surface 3A, which extend from the position of the upper surface 3Ba (recess 3Ca) of the end point detection window 3B to the outer periphery of the polishing surface 3A. Therefore, even if the slurry S or polishing debris flows into the upper surface 3Ba (recess 3Ca) during polishing of the workpiece 2 by the polishing pad 3, it is discharged from the recess 3Ca to the outside of the polishing surface 3A through the radial discharge grooves 3E (see the imaginary arrows in FIG. 4). This makes it possible to prevent the slurry S and polishing debris from accumulating on the upper surface 3Ba and recess 3Ca of the end point detection window 3B. This makes it possible to prevent a decrease in the intensity of the inspection light L1 and the reflected light L2 transmitted through the end point detection window 3B, and thus makes it possible to prevent a decrease in the accuracy of the end point detection by the detection mechanism 7. The upper surface 3Ba of the end point detection window 3 is set lower than the bottom of the discharge groove 3E, and the difference in depth from the polishing surface 3A to the upper surface 3Ba and the bottom of the discharge groove 3E is preferably 0.05 to 0.20 mm. This allows the slurry or the like to be kept in a moderately accumulated state on the upper surface 3Ba of the end point detection window 3B until it is discharged from the discharge groove 3E, making it possible to prevent a decrease in the intensities of the inspection light L1 and the reflected light L2 due to the flow of the slurry or the like, and thus to prevent a decrease in the accuracy of the end point detection by the detection mechanism 7.

[0012] Next, one embodiment of a method for manufacturing the polishing pad 3 configured as above will be described with reference to FIG. That is, first, a mixture of polyisocyanate, which is the material for the end point detection window 3B, and a curing agent is mixed and centrifuged to prepare a mixture, which is then poured into a cylindrical mold and cured to form the columnar portion 102. Next, the columnar portion 102 is placed at a predetermined position in a rectangular box-shaped mold 101 with its axis oriented vertically. Next, polyisocyanate, which is the material of the polishing layer 3C, a hardener, and hollow particles for forming a foam structure are mixed to prepare a mixture 103, which is poured into the mold 101 and hardened (see FIG. 5(a)), forming a block-shaped polyurethane polyurea resin molded body 104 conforming to the internal space of the mold 101 (see FIG. 5(b)). This polyurethane polyurea resin molded body 104 becomes the polishing layer 3C described above. Thereafter, the polyurethane polyurethane resin molding 104 is removed from the formwork 101, and the portion of the polyurethane polyurethane resin molding 104 where the cylindrical portion 102 is embedded is thinly cut along a horizontal plane to the required thickness to cut out as a sheet-like member 107 (see FIG. 5(c)). After that, the surface of the sheet-like member 107 that will become the polishing surface 3A is ground (buffed) as necessary from the viewpoint of thickness correction and fine unevenness formation (sharpening). Then, double-sided tape or the like is attached to the underside of the polishing layer 3C that is opposite to the polishing surface 3A of the sheet-like member 107 (polishing layer 3C). Then, the above-mentioned multiple annular grooves 3Aa are formed by cutting at positions on the concentric circles of the polishing surface 3A of the polishing layer 3C (sheet-like member 107). Then, the upper surface of the cylindrical portion 102 is countersunk to a predetermined depth with the same dimensions as the diameter of the cylindrical portion 102. Then, a linear discharge groove 3E that reaches the outer periphery (outer periphery) of the polishing layer 3C is formed by cutting from the end point detection window 3B radially outward. Then, the support layer 3D (cushion layer) in which the through holes 3Da are formed in advance is attached to the lower surface of the polishing layer 3C with an adhesive or double-sided tape. Finally, the laminate of the sheet-like member 107 (polishing layer 3C) and the support layer 3D is cut into a disk shape. This completes the polishing pad 3 of this embodiment (see FIG. 5(d)). The polishing pad 3 thus manufactured has its lower surface (the lower surface of the support layer 3D) fixed to the upper surface 4A of the polishing platen 4 by means of double-sided tape, adhesive or the like. In this embodiment, the cylindrical portion 102 that will later become the end point detection window 3B is prepared in advance, but the method is not limited to this. As another example, the desired polishing layer can be prepared by pouring the material that will form the end point detection window 3B into a polyurethane-polyurea resin molded body 104 with a hole and then solidifying it. Specifically, a cylindrical extraction member is placed at a predetermined position on the formwork 101 with its axis oriented vertically, and a mixture 103 prepared by mixing polyisocyanate, which is the material for the polishing layer 3C, with a curing agent is poured into the formwork 101 and allowed to harden, forming a polyurethane polyurethane resin molding 104. Next, the cylindrical extractor is pulled upward from the formed polyurethane-polyurea resin molded body 104 to form a cylindrical bottomed hole, and a mixture of polyisocyanate and a hardener, which will be the material for the end point detection window 3B, is poured into the bottomed hole and hardened. The hardened mixture forms a transparent cylindrical portion 102 that will later become the end point detection window 3B. This completes polyurethane polyurea resin molded body 104 in which cylindrical portion 102 is embedded tightly in the bottomed hole. After the step of cutting out a sheet-like member from polyurethane polyurea resin molded body 104, the process can be performed in the same manner as described above. As another example, the desired polishing layer can be produced by cutting the cylindrical portion 102 to a specified thickness and fitting the cut cylindrical portion into a through hole formed in the polishing layer 3C to the same size as the cylindrical portion 102. Specifically, the cylindrical portion 102 and the polyurethane-polyurea resin molded body 104 are prepared in advance. The sheet-like member 107 is cut out from the polyurethane-polyurea resin molded body 104. The surface of the cut-out sheet-like member 107 is ground, and a double-sided tape is attached to the back surface to form an annular groove 3Aa. Then, a through hole of the same size as the cylindrical portion 102 is formed in the sheet-like member 107. Meanwhile, the cylindrical portion 102 is cut to a predetermined thickness, and the cylindrical portion 102 is fitted into the through hole of the sheet-like member 107. This makes it possible to prepare the polishing layer 3C having the end point detection window 3B. The steps after the step of bonding the support layer 3D to the polishing layer 3C can be prepared in the same manner as above. In this example, the desired polishing layer can be prepared without performing countersinking. As another example, the materials of the polishing layer 3C and the end point detection window 3B of this third embodiment are basically the same as those of the first embodiment shown in FIG. 5, but the polishing pad 3 consisting of the polishing layer 3C and the support layer 3D is manufactured as follows. That is, after manufacturing the polishing pad so that the polishing layer 3C and the support layer 3D are overlapped, a through hole is drilled from the front side (upper surface side) of the polishing pad, and the through hole is enlarged by countersinking from the back side (lower surface side) of the polishing pad to the support layer 3D to form a hole, so that the hole and the through hole communicate with each other. Then, an annular groove 3Aa and a discharge groove 3E are formed on the front surface of the polishing pad. Then, a stepped cylindrical end point detection window 3B that has been manufactured separately is fitted into the hole and the through hole from the back side (lower surface side) without any gap. Then, the whole is hot-pressed to press the whole, and the upper surface of the end point detection window 3B is countersunk to a predetermined dimension to form a recess 3Ca. In addition, the end point detection window 3B in this embodiment is made using polyisocyanate and a hardening agent, but the polyisocyanate may be a urethane prepolymer made with polyol or the like. Furthermore, the hardening agent may be a known diol, polyol, diamine, or polyamine. Although hollow fine particles are used to form a foam structure, a chemical foaming agent such as water or an inert gas may be used. Furthermore, in this embodiment, after forming the annular groove 3Aa, countersinking is performed to form the recess 3Ca, and then the discharge groove 3E is formed, but the order of the process of forming the recess 3Ca and the process of forming the discharge groove 3E may be reversed.

[0013] As described above, the polishing pad 3 of this embodiment has the discharge grooves 3E formed on the polishing surface 3A, which extend radially outward from the upper surface 3Ba of the end point detection window 3B and the recessed portion 3Ca. Therefore, during polishing, the slurry and polishing debris are discharged from the upper surface 3Ba and recessed portion 3Ca of the end point detection window 3B to the discharge groove 3E, and the slurry and polishing debris can be prevented from remaining on the upper surface 3Ba and recessed portion 3Ca of the end point detection window 3B, and the transmission of the inspection light L1 and the reflected light L2 irradiated from the detection mechanism 7 through the end point detection window 3B can be suppressed from changing. Therefore, it is possible to prevent the accuracy of the end point detection by the detection mechanism 7 from being reduced by the slurry or the like.

[0014] Next, FIG. 6 shows a second embodiment of the present invention, in which lattice-shaped discharge grooves 13E are formed at equal vertical and horizontal pitches (35 mm) over the entire polishing surface 3A. The vertical and horizontal discharge grooves 13E intersect at the position (recess 3Ca) of the upper surface 3Ba of the end point detection window 3B. Both ends of each linear discharge groove 13E in the lattice shape open to the outer periphery (outer periphery) of the polishing layer 3C, so that the upper surface 3Ba and recess 3Ca of the end point detection window 3B communicate with the outer periphery through the discharge grooves 13E. The width of the discharge grooves 13E is set to 2.0 mm, and the depth is set to 0.6 mm. The depth from the polishing surface 3A to the upper surface 3Ba of the end point detection window 3B is set to 0.8 mm. The other configuration is the same as that of the polishing pad 3 of the first embodiment, and the same member numbers are used for the parts corresponding to those of the first embodiment. The materials of polishing layer 3C and end point detection window 3B and the manufacturing process of polishing pad 3 in this second embodiment are basically the same as those in the first embodiment described above with reference to FIG. In the second embodiment, the upper surface 3Ba and the recess 3Ca of the end point detection window 3B are connected to the outer periphery of the polishing surface 3A by the discharge groove 13E, so that the slurry and polishing debris during polishing are discharged to the outside of the polishing surface 3A through the discharge groove 13E. Therefore, the polishing pad 3 of the second embodiment can provide the same functions and effects as those of the first embodiment. In the second embodiment, the discharge groove 13E is formed substantially perpendicular to or substantially parallel to the annular groove 3Aa, but is not limited thereto. The discharge groove 13E may be formed at a predetermined angle, such as 30°, 45°, or 60°, with respect to the annular groove 3Aa.

[0015] Next, Fig. 7 shows a third embodiment of the present invention. In this third embodiment, based on the first embodiment shown in Fig. 3 and Fig. 4, linear discharge grooves 23E are added to both circumferential sides of the radial discharge groove 3E. These discharge grooves 23E are formed at an angle of 45° with respect to the radial discharge grooves 3E, with the inner end of each discharge groove 23E communicating with the upper surface 3Ba and the recess 3Ca of the end point detection window 3B, and the outer end opening to the outer peripheral edge (outer peripheral portion) of the polishing layer 3C. The width and depth of the discharge grooves 23E are set to the same dimensions as those of the radial discharge grooves 3E. The other configuration is the same as that of the polishing pad 3 of the first embodiment, and the same member numbers are used to designate the parts corresponding to those of the first embodiment. In the polishing pad 3 of the third embodiment, the upper surface 3Ba of the end point detection window 3B, the recess 3Ca, and the outer periphery of the polishing surface 3A are connected by three discharge grooves 3E and 23E, so that the slurry and polishing debris during polishing are efficiently discharged to the outside of the polishing surface 3A through the discharge grooves 3E and 23E. This makes it possible to prevent the slurry and polishing debris from accumulating on the upper surface 3Ba of the end point detection window 3B. Therefore, the polishing pad 3 of the third embodiment can also obtain the same functions and effects as those of the first embodiment.

[0016] In each of the above embodiments, the explanation is based on the assumption that the centers of the multiple annular grooves 3Aa arranged at concentric positions coincide with the center of the polishing surface 3A, but the center of the annular groove 3Aa may be eccentric with respect to the center of the polishing surface 3A. [Explanation of symbols]

[0017] 1...Polishing equipment 2...Object to be polished (wafer) 3...Polishing pad 3A...Polishing surface 3B: Window for end point detection 3C: Polishing layer 3Ba...Top surface 3E, 13E, 23E...Drain groove 7…Detection mechanism L1…Inspection light

Claims

1. A polishing pad comprising a polishing layer having a polishing surface for polishing an object to be polished, and a transparent end point detection window provided in the polishing layer for detecting an end point during polishing, a surface of the end point detection window facing the polishing surface is formed to be lower than the polishing surface, and a recess is formed between the end point detection window and the polishing surface; Furthermore, at least one discharge groove is formed in the polishing surface, the discharge groove communicating with the recessed portion and the outer peripheral edge of the polishing surface, The slurry and polishing waste during polishing are discharged from the recess to the outside of the polishing surface through the discharge groove. A plurality of annular grooves are formed at concentric positions on the polishing surface, The discharge groove is provided so as to intersect with the annular groove, a surface of the end point detection window facing the polishing surface is lower than a bottom of the annular groove; Furthermore, the polishing pad is characterized in that the bottom of the discharge groove is at the same height as or lower than the bottom of the annular groove, and is higher than one surface of the end point detection window on the polishing surface side.

2. 2. The polishing pad according to claim 1, wherein a difference between a depth from the polishing surface to a surface of the end point detection window facing the polishing surface and a depth of the discharge groove is 0.05 to 0.20 mm.

3. 3. The polishing pad according to claim 1, wherein the discharge grooves on the polishing surface include a first discharge groove formed radially from the recess, and a second discharge groove formed at a predetermined angle relative to the first discharge groove.

4. a lattice-like groove is formed on the polishing surface, the lattice-like groove being formed by intersecting a plurality of linear grooves; The polishing pad according to claim 1 or 2, characterized in that at least one linear groove constituting the grid-shaped groove is arranged to intersect with a recess of the end point detection window, and the one linear groove serves as the discharge groove.

Images