Polishing Pad

Abstract

To provide a polishing pad which decreases entrance of polishing dust, etc. to between an endpoint detection window and an object to be polished as much as possible and prevents the precision of end-point detection on polishing from lowering due to the endpoint detection window.SOLUTION: A polishing pad 3 includes a polishing layer 3A which has a polishing face 3a for polishing an object to be polished and an end point detection window 8 which is provided on the polishing layer 3A, transmits detection light applied from end point detection means and detects an end point of polishing, in the polishing pad 3 performing polishing of the object to be polished while interposing slurry between the polishing face 3a and the object to be polished, a barrier groove 12 is provided in a direction which intersects to the rotation direction on a position in the vicinity of the front side and the rear side of rotation direction of the polishing pad 3 with respect to the window 8 for end point detection, and a tapered shape 12a which expands toward the side of object to be polished is provided on the barrier groove 12.SELECTED DRAWING: Figure 5

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. [Background technology]

[0002] Polishing pads equipped with a transparent end point detection window for detecting the end point of the polishing process have been known in the past, and one such polishing pad is known in which the surface of the end point detection window is formed at the same height as the polishing surface (see, for example, Patent Document 1). When polishing an object to be polished using the polishing pad, a liquid slurry is supplied between the polishing pad and the object to be polished. If polishing debris generated during polishing enters between the end point detection window and the object to be polished together with the slurry, the inspection light passing through the end point detection window will be blocked by the polishing debris, which may reduce the accuracy of end point detection. Therefore, in Patent Document 1, multiple concentric annular grooves are formed on the polishing surface of the polishing pad, and the annular grooves at the same radial position as the end point detection window have their ends formed in a position close to the end point detection window, so as to form a flat barrier area around the end point detection window. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2010-536583 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when the workpiece is polished with the polishing pad, the polishing is performed while rotating, so that the rotation of the polishing pad causes polishing debris to accumulate at the rear end in the direction of rotation of the annular groove at the same radial position as the end point detection window in the polishing pad of Patent Document 1. Since the end of the annular groove is located in front of the end point detection window in the rotation direction, if the polishing debris is discharged from the end of the annular groove, it may cross the barrier area and get between the end point detection window and the workpiece, thereby reducing the accuracy of the end point detection. In other words, the configuration of Patent Document 1 has a problem that the effect of suppressing the deterioration of the end point detection accuracy due to the polishing debris is extremely limited. In view of these problems, the present invention provides a polishing pad that minimizes the ingress of polishing debris and the like between the end point detection window and the workpiece, prevents a decrease in the accuracy of end point detection by the end point detection window, and minimizes the impact on polishing performance. [Means for solving the problem]

[0005] That is, the present invention teeth, a polishing layer having a polishing surface for polishing an object to be polished; and an end point detection window provided in the polishing layer for detecting an end point of a polishing process by transmitting an inspection light irradiated from an end point detection means; A polishing pad for polishing an object to be polished while the polishing surface rotates relative to the object to be polished and a slurry is interposed between the polishing surface and the object to be polished, At positions adjacent to the front and rear of the end point detection window in the direction of rotation of the polishing pad, A pair This is characterized by providing a barrier groove, which has a tapered shape that widens toward the workpiece side. Effect of the Invention

[0006] According to the above-mentioned invention, the end point detection window is provided on the front side and the rear side of the polishing pad in the rotation direction. A pair When the polishing debris in the slurry is collected in the barrier groove, the polishing debris that has flowed into the barrier groove is moved to the outer peripheral end of the barrier groove by the centrifugal force caused by the rotation of the polishing pad, since the barrier groove is formed in a direction that intersects with the rotation direction. In particular, the polishing debris discharged from the outer end of the barrier groove, which is located forward in the rotational direction from the end point detection window, does not get caught between the end point detection window and the workpiece, so that the amount of polishing debris that gets caught between the end point detection window and the workpiece can be minimized, and the detection accuracy by the end point detection window can be maintained. Furthermore, by forming a tapered shape in the barrier groove, excessive polishing of the workpiece by the edge of the barrier groove on the polishing surface side can be prevented, and furthermore, deformation of the polishing surface caused by friction (shear stress) between the end point detection window and the workpiece, which occurs due to the barrier groove preventing slurry from getting between the end point detection window and the workpiece, can be absorbed, thereby suppressing uneven polishing. [Brief description of the drawings]

[0007] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 4 is an enlarged plan view of the polishing pad showing the vicinity of the end point detection window. [Diagram 5] 5 is a cross-sectional view of the VV portion in FIG. 4. [Figure 6] 11A to 11C are cross-sectional views showing other configurations of the barrier groove. [Figure 7] FIG. 13 is a diagram for explaining a state of a barrier groove in which a tapered shape 12a is not formed. [Figure 8] 4A to 4C are diagrams illustrating a method for manufacturing a polishing layer. [Figure 9] FIG. 11 is an enlarged plan view of a polishing pad showing the vicinity of an endpoint detection window according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will now be described with reference to the illustrated embodiment. FIGS. 1 and 2 respectively show a schematic diagram and a cross-sectional view of a polishing apparatus 1, in which a thin plate-shaped object to be polished 2 (e.g., a semiconductor wafer) is polished by a disk-shaped polishing pad 3. The polishing apparatus 1 comprises 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 an object to be polished 2 on its lower surface, a slurry supplying means 6 for supplying a slurry S (polishing liquid) between the object to be polished 2 and the polishing pad 3, and an end point detecting means 7 for detecting the progress of the polishing of the object to be polished 2. The workpiece 2 can be an optical material, a silicon wafer, a glass substrate for liquid crystal display, a semiconductor substrate, or a plate-like object such as glass, metal, ceramic, etc., and the slurry S supplied by the slurry supply means 6 can be appropriately selected according to the workpiece 2. The polishing platen 4 and the holding platen 5 each have a substantially disk-like shape, and the polishing pad 3 and the workpiece 2 attached thereto also have a substantially disk-like shape. The polishing platen 4 and the holding platen 5 are rotatably provided by a drive mechanism (not shown), and the holding platen 5 rotates while revolving around the center of rotation of the polishing platen 4. When polishing the object 2, the holding platen 5 rotates while pressing the object 2 against the polishing surface 3a of the polishing pad 3 held on the polishing platen 4 with the required pressure, and in this state the slurry supply means 6 supplies slurry S between the object 2 and the polishing pad 3, so that the object 2 is polished by the polishing pad 3.

[0009] As shown in FIG. 2, the end point detection means 7 is provided below the polishing table 4, irradiates an inspection light L1 upward and receives a reflected light L2 reflected by the workpiece 2 to detect the progress of the polishing process and the end point where the process ends based on the received reflected light L2. A through hole 4a is provided at a predetermined position of the polishing table 4 to allow the inspection light L1 and reflected light L2 to pass through, and a transparent window 8 for detecting the end point is provided in the polishing pad 3 in accordance with the position of the through hole 4a. As shown in FIG. 3, the polishing pad 3 is provided with three end point detection windows 8 at equal intervals at required radial positions, and in this embodiment, the diameter of the end point detection windows 8 is about 9 mm. In this embodiment, the end point detection window 8 is circular, but it may be of various other shapes, such as a rectangle, a square, a polygon, an ellipse, etc. Also, in this embodiment, three end point detection windows 8 are provided at equal intervals at required radial positions on the polishing pad 3, but the position is not limited to this and it is sufficient that at least one window is provided. While the workpiece 2 is being polished, the end point detection means 7 irradiates the inspection light L1 upward, the inspection light L1 passes through a transparent end point detection window 8 and is reflected downward from the surface of the workpiece 2, and the reflected light L2 passes through the transparent end point detection window 8 and is received by the end point detection means 7. The end point detection means 7 detects changes in the intensity of the reflected light L2 as the polishing of the workpiece 2 progresses and the polished surface of the workpiece 2 is gradually polished. When the detected intensity of the reflected light L2 reaches a preregistered intensity, it is determined that the polished surface has reached the end point of processing. Furthermore, when the object to be polished 2 is a semiconductor substrate or the like having a coating formed on its surface, the progress of the polishing process is detected by detecting the change in the thickness of the film formed on the surface of the object to be polished 2 during polishing using optical interference. In this case, the inspection light L1 incident on the object to be polished 2 is reflected by the surface of the thin film and the interface between the thin film and the substrate, which results in an optical path difference between the reflected light L2 reflected by the surface of the thin film and the reflected light L2 reflected by the interface between the thin film and the substrate, and also in a phase difference between the two reflected lights L2. The phase difference of the reflected light L2 changes when the film thickness changes as the workpiece 2 is polished, and it is possible to detect the progress and end point of the polishing process based on the change in the phase difference.

[0010] As shown in Figure 3, the polishing pad 3 has three end point detection windows 8 provided at required radial positions, a plurality of annular grooves 11 formed concentrically around the center (center of rotation) of the polishing pad 3, and barrier grooves 12 provided in close proximity to the front and rear of the end point detection windows 8 in the direction of rotation of the polishing pad 3. Here, the polishing apparatus 1 of this embodiment is configured to rotate the polishing pad 3 in a clockwise direction as shown in Fig. 3. The rotation direction of the polishing pad 3 may be reversed, or may be reversed during polishing operation. Here, Figure 2 shows a portion from which the cross-sectional view shown in part II-II in Figure 3 can be obtained, and the polishing pad 3 comprises a polishing layer 3A having a polishing surface 3a formed on the side of the workpiece 2 to be polished, and a support layer 3B (cushion layer) formed on the polishing table 4 side of the polishing layer 3A. The polishing layer 3A is composed of a sheet having a foam structure made of an elastic resin such as polyurethane with a thickness of 0.8 to 2.6 mm. Due to this foam structure, when polishing, openings due to the foam structure are formed on the polishing surface, and the slurry can be stored, thereby improving the polishing efficiency. More specifically, a foam sheet made of an elastic resin such as polyurethane, in which numerous voids of submicron unit to tens of microns are formed inside, can be used. The support layer 3B may be a woven or nonwoven fabric impregnated with a resin such as polyurethane, a resin foam such as polyurethane, or a resin sheet such as polyester, having a thickness of 0.1 to 5.0 mm. In particular, it is preferable to use a woven or nonwoven fabric impregnated with a resin such as polyurethane, or a resin foam such as polyurethane as the support layer 3B having voids formed therein, as these have excellent cushioning properties to prevent overpolishing. The polishing layer 3A and the support layer 3B are bonded together with an adhesive or double-sided tape, and the lower surface of the support layer 3B is fixed to the upper surface of the polishing platen 4 with an adhesive or double-sided tape.

[0011] The end point detection window 8 is made of a transparent material that transmits light, and can be made of, for example, an elastic resin such as polyurethane, similar to the polishing layer 3A. However, the window 8 for end point detection must have a structure that avoids foaming that would hinder light transmission in order to allow the transmission of the inspection light L1 and the reflected light L2. More specifically, therefore, it is preferable to use an elastic resin such as polyurethane that does not form voids inside. Furthermore, the end point detection window 8 fits snugly into a through hole formed at a predetermined position in the polishing layer 3A, and the upper and lower surfaces of the end point detection window 8 are formed flush with the polishing surface 3a and lower surface of the polishing layer 3A, respectively. In particular, by arranging the upper surface of the end point detection window 8 flush with the polishing surface 3a, the end point detection window 8 and the workpiece 2 are grounded during polishing, thereby preventing the presence of slurry from interfering with the transmission of the inspection light L1 and the reflected light L2. Furthermore, by making the lower surface of the end point detection window 8 flush with the lower surface of the polishing layer 3A, even if the polishing pad 3 is worn down by polishing, it can be used right up to the lower surface of the polishing layer 3A. Conversely, if the lower surface of the end point detection window 8 protrudes further toward the support layer 3B than the lower surface of the polishing layer 3A, the initial thickness of the end point detection window 8 becomes excessively large, which promotes the obstruction of the transmission of the inspection light L1 and the reflected light L2, which is not preferable. A through hole 3Ba is drilled in the support layer 3B to match the position of the end point detection window 8, and when the polishing pad 3 is attached to the polishing platen 4, the end point detection window 8 and the through hole 3Ba are aligned with the position of the through hole 4a formed in the polishing platen 4.

[0012] As shown in FIG. 3, the annular groove 11 is formed concentrically around the center of rotation of the polishing pad 3, and is formed endlessly except for the one formed at the same radial position as the end point detection window 8 described later. In this embodiment, each of the annular grooves 11 is set to a width of 0.4 mm and a depth of 0.6 mm, and the pitch between adjacent annular grooves 11 is set to 2.8 mm. The annular groove 11 formed at the same radial position as the end point detection window 8 is an ended groove having ends in positions close to the end point detection window 8. The width, depth, and pitch can be the same as those of the endless annular groove 11. Here, the annular groove 11 at the same radial position as the end point detection window 8 refers to an annular groove 11 formed at a position where the annular groove 11 would intersect or interfere with the end point detection window 8 if the annular groove 11 were formed endless. Furthermore, in the case where the annular groove 11 does not intersect with the end point detection window 8, for example, in the case of an annular groove 11 located radially inward or outward from the end point detection window 8, if a flat surface of the required width cannot be secured between the annular groove and the end point detection window 8, the annular groove can also be treated as an annular groove 11 at the same radial position as the end point detection window 8, and can be made into a groove with ends that avoids the end point detection window 8.

[0013] Fig. 4 shows an enlarged view of the vicinity of the end point detection window 8 on the polishing surface 3a of the polishing pad 3. In Fig. 4, as the polishing pad 3 rotates, the end point detection window 8 moves from the rear in the direction of rotation (rightward in the figure) to the front in the direction of rotation (leftward in the figure). The barrier groove 12 is formed in a direction intersecting the rotation direction of the polishing pad 3 , and specifically, the barrier groove 12 is formed in a radial direction passing through the vicinity of the center of the polishing pad 3 . In addition, the barrier groove 12 is formed in a position close to the front and rear of the end point detection window 8 in the rotation direction, for example, at a position 3 to 20 mm, preferably 5 to 10 mm, away from the end of the end point detection window 8. By separating the barrier groove 12 by at least 3 mm from the end of the end point detection window 8, it is possible to prevent the end point detection window 8 from peeling off from the polishing layer 3A due to differences in friction between the end point detection window 8 and the polished object 2 during polishing of the polishing layer 3A or differences in deformation. On the other hand, by providing the barrier groove 12 20 mm or less from the end of the end point detection window 8, it is possible to prevent slurry from getting between the end point detection window 8 and the polished object 2. The barrier groove 12 is connected to the end of an annular groove 11 formed at the same radial position as the end point detection window 8, and both ends of the barrier groove 12 are formed up to the positions of the annular grooves 11 located on the outermost and innermost sides of the annular grooves 11 formed at the same radial position as the end point detection window 8. As a result, a flat surface formed by the polished surface 3a is formed around the end point detection window 8; in other words, no grooves are formed in the end point detection window 8 or in the vicinity of the end point detection window 8.

[0014] FIG. 5 shows a cross-sectional view of the VV portion of polishing layer 3A, specifically, a cross-sectional view of polishing layer 3A cut along the direction of rotation of polishing pad 3. The barrier groove 12 has the same dimensions as the annular groove 11 in width and depth, but the barrier groove 12 in this embodiment has a tapered shape 12a that widens toward the workpiece 2 side. The tapered shape 12a may be formed by chamfering the corner of the inner wall of the vertically formed barrier groove 12 on the polishing surface 3a side at an angle of 45° at a depth of about 0.1 mm, or may be formed by a single inclined surface extending from the bottom surface of the barrier groove 12 toward the polishing surface 3a, as shown in FIG. 6. Here, the chamfer angle of the tapered shape 12a with respect to the polishing surface 3a is preferably 30 to 80°. By making it 30° or more, it is possible to make it difficult for deformation due to friction to affect the polishing surface 3a, and by making it 80° or less, it is possible to suppress the edge effect. In particular, by making it 70° or less, it is possible to make it difficult for deformation due to friction to affect the polishing surface 3a. Furthermore, it is preferable to set the chamfer depth of the tapered shape 12a to 0.1 mm or more, since this makes it possible to prevent deformation due to friction from affecting the polishing surface 3a. Here, the shape of the barrier groove 12 may be appropriately changed depending on the purpose of discharging polishing debris in the slurry S and the degree of deformation of the polishing layer 3A described later.

[0015] When polishing the workpiece 2 using the polishing pad 3 having the above-mentioned configuration, as described above, slurry S is supplied between the workpiece 2 and the polishing pad 3, and when this slurry S enters the annular groove 11 and the barrier groove 12, the slurry S is supplied between the workpiece 2 and the polishing pad 3. Here, the polishing pad 3 is rotated by the polishing platen 4, and the end point detection window 8 moves from the right to the left in Fig. 5. This generates a relative flow of the slurry S from the front (left in the figure) to the rear (right in the figure) in the direction of rotation with respect to the end point detection window 8. In addition, when the workpiece 2 is polished by the polishing pad 3, polishing debris is generated, and together with the slurry S, this polishing debris attempts to enter between the end point detection window 8 and the workpiece 2 from the front of the end point detection window 8. Furthermore, if polishing debris gets between the end point detection window 8 and the workpiece 2, the intensity of the inspection light L1 and the reflected light L2 passing through the end point detection window 8 will decrease, which may reduce the accuracy of end point detection.

[0016] In contrast, the polishing pad 3 of this embodiment is provided with the barrier groove 12 on both the front and rear sides of the end point detection window 8 in the rotational direction, thereby minimizing the decrease in end point detection accuracy as described below. As described above, the polishing debris flows from the front of the end point detection window 8 in the rotation direction together with the slurry S, but the polishing debris is collected by the barrier groove 12 provided in front of the end point detection window 8 in the rotation direction. Since the barrier groove 12 is arranged in a direction intersecting the direction of rotation, the centrifugal force caused by the rotation of the polishing pad 3 moves the polishing debris to the outer periphery of the barrier groove 12, and then the debris is discharged from the end of the barrier groove 12 on the outer periphery. Since the polishing debris discharged from the outer end of the barrier groove 12 has already been removed from the front of the end point detection window 8 in the rotational direction, the polishing debris is prevented as much as possible from getting between the end point detection window 8 and the workpiece 2, and the deterioration of the end point detection accuracy can be suppressed as much as possible.

[0017] Furthermore, in this embodiment, the polishing debris also enters the annular groove 11 formed on the polishing surface 3a, but the polishing debris that enters the annular groove 11 formed at the same radial position as the end point detection window 8 moves backward in the rotational direction along the annular groove 11 as the polishing pad 3 rotates. The polishing groove that reaches the rear end of the annular groove 11 in the rotational direction flows directly into the barrier groove connected to the annular groove 11, and then is discharged from the outer peripheral end of the barrier groove 12 as described above. In this way, by connecting the end of the annular groove 11, which is formed at the same radial position as the end point detection window 8, to the barrier groove 12, polishing debris that has entered the annular groove 11 can be prevented from entering between the end point detection window 8 and the workpiece 2.

[0018] Next, the tapered shape 12a formed in the barrier groove 12 of this embodiment will be described. Like FIG. 5, FIG. 7 shows a cross-sectional view along the rotation direction of the polishing pad 3, but the barrier groove 12 shown in FIG. 7 omits the tapered shape 12a, and also shows a schematic diagram of the state when the polishing pad 3 is rotating and polishing the workpiece 2. If the barrier groove 12 does not have the tapered shape 12a, the sidewall constituting the barrier groove 12 will come into contact with the object 2 to be polished perpendicularly. When the polishing pad 3 rotates in this state, since the barrier groove 12 is arranged in a direction intersecting the direction of rotation, a so-called edge effect occurs at the contact portion with the side wall of the barrier groove 12, particularly at the contact portion with the side wall located rearward in the direction of rotation, and the side wall of the barrier groove 12 may polish the workpiece 2 excessively, which may cause uneven polishing. In contrast, the polishing pad 3 of this embodiment has a tapered shape 12a in the barrier groove 12 as shown in FIG. 5, so that the occurrence of polishing unevenness due to the edge effect is prevented.

[0019] Next, since the end point detection window 8 of the polishing pad 3 in this embodiment is formed flush with the polishing surface 3a, when the end point detection window 8 and the workpiece 2 are in close contact with each other, a greater frictional force is generated between the end point detection window 8 and the workpiece 2 than between the other parts of the polishing surface 3a and the workpiece 2. This phenomenon occurs because the polishing surface 3a has openings due to a foam structure that stores the slurry S, while the end point detection window 8 has a structure that avoids foaming that would hinder light transmission in order to allow the inspection light L1 and reflected light L2 to pass through, so that the surface of the end point detection window 8 has a structure in which the openings due to the foam structure are limited, and the area ratio in contact with the polished object 2 is large, resulting in a state in which it is susceptible to frictional forces. Furthermore, by forming the barrier groove 12, the intrusion of slurry S between the end point detection window 8 and the object to be polished 2 is suppressed, making it easier for the end point detection window 8 and the object to be polished 2 to come into direct contact with each other, which is thought to generate a larger frictional force (shear stress) than in the portion between the polishing surface 3a and the object to be polished 2. Furthermore, as described above, since the end point detection window 8 has a structure that prevents foaming, the end point detection window 8 is not easily deformed. Therefore, when the polishing pad 3 rotates, the above-mentioned frictional force (shear stress) pulls the end point detection window 8 backward in the direction of rotation, causing the polishing layer 3A formed between the end point detection window 8 and the barrier groove 12 to deform. As a result, as shown in Figure 7, for the barrier groove 12 formed behind the end-point detection window 8 in the rotational direction, the deformation of the polishing layer 3A causes the polishing surface 3a of the deformed portion to rise, which may result in uneven polishing. Therefore, in the polishing pad 3 of this embodiment, a tapered shape 12a is provided in the barrier groove 12 as shown in FIG. 5, so that deformation of the polishing layer 3A can be absorbed by the tapered shape 12a, thereby preventing uneven polishing.

[0020] Here, in the barrier groove 12 provided in front and behind the end point detection window 8 in the rotational direction, what prevents the occurrence of the above-mentioned polishing unevenness is the tapered shape 12a formed on the front side of the barrier groove 12 on the rear side in the rotational direction from the end point detection window 8. Therefore, the tapered shape 12a at the front in the rotational direction of the barrier groove 12 forward of the end point detection window 8 can be omitted, but taking into account that the polishing pad 3 will be rotated in the opposite direction, it is desirable to provide the above-mentioned tapered shape 12a at both the front and rear of the barrier groove 12 in the rotational direction.

[0021] Next, one embodiment of a method for manufacturing the polishing pad 3 configured as above will be described with reference to FIG. First, a rectangular parallelepiped mold 101 is prepared, and a cylindrical extractor 102 is placed at a predetermined position of the mold 101, which is adapted to the outer diameter of the end point detection window 8. A mixture of polyisocyanate, which is the material of the polishing layer 3A, a hardener, and hollow fine particles of vinylidene chloride-acrylonitrile copolymer is poured into the mold 101 and hardened to form a foam structure (FIG. 8(a)). This forms a block-shaped polyurethane polyurea resin molded foam 103 that will later constitute the polishing layer 3A. Next, the cylindrical removal member 102 is removed from the resin molded foam 103, and a cylindrical space 102' is formed in the resin molded foam 103, and a mixture of polyisocyanate and a hardener, which is the material for the end point detection window 8, is poured into the cylindrical space 102' after being degassed as necessary and then hardened (FIG. 8(b)). This forms a transparent cylindrical portion 104 that will later constitute the end point detection window 8. Next, the resin molded foam 103 and the cylindrical portion 104 are removed from the mold 101 and cut thinly to match the thickness of the polishing layer 3A of the polishing pad 3, to be cut out as a sheet-like member 105 (FIG. 8(c)). At this time, the upper and lower surfaces of the end-point detection window 8 are formed flush with the upper and lower surfaces of the polishing layer 3A. Finally, the sheet-like member 105 is cut into a disk shape, and then, if necessary, the surface to be the polishing surface 3a is ground (buffed) in order to correct the thickness and form fine irregularities (sharpening), and the polishing surface 3a is cut to form the annular groove 11 and the barrier groove 12 (not shown), and further, the barrier groove 12 is cut to form the tapered shape 12a (not shown) (Figure 8(d)). Once the polishing layer 3A of the polishing pad 3 is obtained in this manner, the lower surface opposite the polishing surface 3a is then attached to the support layer 3B (cushion layer) with double-sided tape or the like, and the polishing pad 3 is completed. In this embodiment, the cylindrical portion 104, which will later become the end point detection window 8, is produced by pouring material into a cylindrical space 102' formed in the resin molded foam 103. However, the cylindrical portion 104 may be prepared in advance, placed in a predetermined position in the form 101, and the material for the polishing layer 3A may be poured into the form 101 and allowed to harden. Further, in the present embodiment, the polishing layer 3A and the end point detection window 8 are made of polyisocyanate and a hardening agent, but the polyisocyanate may be a prepolymer made from polyol or the like. The curing agent may be any one having a plurality of functional groups, such as hydroxyl groups or amino groups, that react with isocyanates, and may be a polyol or polyamine whose chain has been extended with polyisocyanate or the like. Furthermore, in this embodiment, hollow microparticles of vinylidene chloride-acrylonitrile copolymer were used to form a foam structure in the polishing layer 3A, but chemical foaming agents such as water or inert gases may also be used alone or in combination.

[0022] FIG. 9 is a diagram for explaining a polishing pad 3 according to a second embodiment, and like FIG. 4, is an enlarged plan view of the vicinity of an end point detection window 8 provided on a polishing surface 3a. In this embodiment, the barrier groove 12 is connected to endless annular grooves 11 adjacent to the outer and inner sides in the radial direction of the end point detection window 8 . In the first embodiment, the annular groove 11 at the same radial position as the end point detection window 8 is a groove with ends, and the barrier groove 12 connects the ends of the annular groove 11 with ends, but in this embodiment, the barrier groove 12 is extended further radially and connected to the endless annular grooves 11 located on the outer and inner sides of the end point detection window 8. With this configuration, the polishing debris collected in the barrier groove 12 moves toward the outer periphery along the barrier groove 12 as the polishing pad 3 rotates and flows into the endless annular groove adjacent to the outer periphery of the end point detection window 8, making it possible to remove the polishing debris from in front of the end point detection window 8 in the rotational direction without flowing out onto the polishing surface 3a.

[0023] In the second embodiment, the barrier groove 12 is extended to the endless annular grooves 11 adjacent to the radially outer and inner sides of the end point detection window 8, but it may be extended to either the outer or inner annular groove. However, since the polishing debris collected in the barrier groove 12 is directed radially outward by the centrifugal force of the polishing pad 3, it is desirable to connect the barrier groove 12 to the radially outer annular groove 11 to prevent the polishing debris from flowing out onto the polishing surface 3a. In the second embodiment, the barrier groove 12 extends to the endless annular groove 11 provided at the position closest to the end-point detection window 8, but the barrier groove 12 may be extended to intersect with a plurality of endless annular grooves 11. More specifically, the radially outer end of the barrier groove 12 may be extended to the outer periphery of the polishing pad 3.

[0024] Furthermore, in each of the above embodiments, the explanation is based on the assumption that the centers of the multiple annular grooves 11 arranged at concentric positions coincide with the center of the polishing surface 3a, but the center of the annular groove 11 may be eccentric with respect to the center of the polishing surface 3a. [Explanation of symbols]

[0025] 1 Polishing device 2 Object to be polished 3 Polishing pad 3A Polishing layer 7 End point detection means 8 End point detection window 11 Annular groove 12 Barrier groove 12a Tapered shape

Claims

1. a polishing layer having a polishing surface for polishing an object to be polished; and an end point detection window provided in the polishing layer for detecting an end point of a polishing process by transmitting an inspection light irradiated from an end point detection means; A polishing pad which polishes an object to be polished while the polishing surface rotates relative to the object to be polished and a slurry is interposed between the polishing surface and the object to be polished, A polishing pad characterized in that a pair of barrier grooves are provided in a direction intersecting the rotation direction at positions close to the front and rear of the end point detection window in the rotation direction of the polishing pad, and the barrier grooves are provided with a tapered shape that widens toward the workpiece.

2. forming a plurality of concentric annular grooves on the polishing surface; The polishing pad of claim 1, characterized in that among the annular grooves, an annular groove formed at the same radial position as the end point detection window is a groove with ends connected to the barrier groove.

3. 3. The polishing pad according to claim 2, wherein the barrier groove extends to an endless annular groove adjacent at least one of the radially outer side and the radially inner side of the end point detection window.

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