Polishing pad

Abstract

A disk-shaped polishing pad (1) in which a polishing layer is formed on the obverse-surface side thereof has a disk-shaped base material (2) and a first adhesive layer (5) laminated on the reverse-surface side of the base material (2), the base material (2) and the first adhesive layer are configured from a light-transmitting material, the polishing layer has a plurality of polishing parts (3) discretely arranged at even intervals on the obverse surface of the base material (2), and the transmittance of visible light in portions from the polishing parts (3) to the first adhesive layer (5) is 30% or greater. As a result, an opening (7) can easily be provided facing the position of a coolant supply port (15) in a state in which the polishing pad (1) is affixed to an upper surface plate (11).

Description

Polishing Pad

[0001] The present invention relates to a polishing pad used in a double-sided polishing apparatus or the like for polishing a wafer, a glass substrate, or the like.

[0002] Conventionally, for example, as in Patent Document 1, a disk-shaped carrier provided with a plurality of holding holes for holding a plurality of workpieces to be polished respectively, and an upper platen and a lower platen that sandwich the carrier from above and below and rotate relatively. It has a platen, an upper polishing cloth attached to the lower surface of the upper platen, and a lower polishing cloth attached to the upper surface of the lower platen. While rotating the carrier between the upper polishing cloth attached to the upper platen and the lower polishing cloth attached to the lower platen, the carrier is revolved while rotating to polish the front and back surfaces of the workpiece. A double-sided polishing apparatus is known.

[0003] And, in the upper polishing cloth, opening holes are provided at positions facing a plurality of coolant supply ports for supplying a coolant containing an abrasive, which open to the upper platen.

[0004] Japanese Patent Application Laid-Open No. 2024-88310

[0005] However, since the position and size of the coolant supply port in the double-sided polishing apparatus vary depending on the model, if opening holes corresponding thereto are provided in advance as in Patent Document 1, there is a problem of low versatility.

[0006] The present invention has been made in view of such a point, and the object thereof is to be able to easily provide an opening in accordance with the position of the coolant supply port in a state where the polishing pad is attached to the upper platen.

[0007] In order to achieve the above object, in this invention, the polishing pad is configured to be transmissive to visible light.

[0008] Specifically, the first invention provides a polishing pad comprising a disc-shaped base material, a polishing layer formed on the surface side of the base material, and a first adhesive layer laminated on the back side of the base material, wherein the polishing layer has a plurality of polishing parts discretely and evenly spaced apart on the surface of the base material, the base material and the first adhesive layer are made of a light-transmitting material, and the visible light transmittance of the portion from the base material to the first adhesive layer in the region where the surface of the base material is exposed is 30% or more.

[0009] According to the above configuration, by setting the visible light transmittance of the portion from the polishing section to the first adhesive layer to 30% or more, when the first adhesive layer is attached to the underside of the upper platen of the double-sided polishing device, visible light can be transmitted from the side of the coolant supply port to confirm the position of the coolant supply port from the polishing layer side, and an opening corresponding to the coolant supply port can be formed from the polishing layer side. On the other hand, if the transmittance is lower than 30%, it is not easy to confirm the coolant supply port. Here, "evenly spaced" means that the polishing section is not concentrated in one area, nor are there gaps that are too large in some areas.

[0010] In the second invention, the first invention comprises a disc-shaped support bonded to the back surface of the substrate via the first adhesive layer, and a second adhesive layer laminated on the back surface of the support, wherein the support and the second adhesive layer are made of a light-transmitting material, and the visible light transmittance of the portion from the substrate to the second adhesive layer in the region where the surface of the substrate is exposed is 30% or more.

[0011] According to the above configuration, by setting the visible light transmittance of the portion from the polishing section to the second adhesive layer to 30% or more, when the second adhesive layer is attached to the underside of the upper platen of the double-sided polishing device, visible light can be transmitted from the side of the coolant supply port to confirm the position of the coolant supply port from the polishing layer side, and an opening corresponding to the coolant supply port can be formed from the polishing layer side. On the other hand, if the transmittance is lower than 30%, it is not easy to confirm the coolant supply port.

[0012] In the third invention, in the first or second invention, the ratio of the area occupied by the polished portion to the entire surface of the substrate in the polished layer is 26% or more and 60% or less.

[0013] If the aforementioned ratio is greater than 60%, the spacing between the non-transparent polishing areas becomes too narrow, making it difficult to pass visible light through and thus difficult to confirm the location of the coolant supply port. Conversely, if the aforementioned ratio is less than 26%, the proportion of polishing areas is too low, preventing the proper polishing performance from being ensured. Also, if the spacing between polishing areas becomes too wide, the workpiece may get caught and be damaged. However, by setting the aforementioned ratio between 26% and 60%, the proper polishing performance can be ensured while the location of the coolant supply port can be easily confirmed, resulting in improved work efficiency.

[0014] In the fourth invention, in any one of the first to third inventions, the substrate is formed from at least one selected from polycarbonate, polyvinyl chloride, and polyethylene terephthalate, which is permeable or transparent.

[0015] According to the above configuration, a substrate that is readily available, highly transparent, and durable can be obtained.

[0016] In the fifth invention, in the first invention, with the first adhesive layer attached to the lower surface of the upper platen of the double-sided polishing apparatus, visible light is transmitted from the side of the coolant supply port to confirm the position of the coolant supply port from the side of the polishing layer, and an opening corresponding to the coolant supply port is formed from the side of the polishing layer.

[0017] Furthermore, in the method using the polishing pad of the first invention, the method may also include the step of attaching the first adhesive layer to the lower surface of the upper platen of the double-sided polishing apparatus, transmitting visible light from the side of the coolant supply port to confirm the position of the coolant supply port from the side of the polishing layer, and forming an opening corresponding to the coolant supply port from the side of the polishing layer.

[0018] In the sixth invention, in the second invention, with the second adhesive layer attached to the lower surface of the upper platen of the double-sided polishing apparatus, visible light is transmitted from the side of the coolant supply port to confirm the position of the coolant supply port from the side of the polishing layer, and an opening corresponding to the coolant supply port is formed from the side of the polishing layer.

[0019] Furthermore, in the method using the polishing pad of the second invention, the second adhesive layer may be attached to the lower surface of the upper platen of the double-sided polishing apparatus, and the position of the coolant supply port may be confirmed from the polishing layer side by transmitting visible light from the side of the coolant supply port, and an opening corresponding to the coolant supply port may be formed from the side of the polishing layer.

[0020] With these configurations, even if the position of the coolant supply port in the double-sided polishing machine differs from model to model, the position of the visible light can be checked when the polishing pad is attached to the underside of the upper platen, and an opening corresponding to the coolant supply port can be formed in the polishing pad from below, so that the opening can be provided in the optimal position.

[0021] As described above, according to the present invention, an opening can be easily made in line with the position of the coolant supply port while the polishing pad is attached to the upper platen.

[0022] This is a plan view showing an overview of a polishing pad according to an embodiment of the present invention. This is a cross-sectional view showing an overview of a polishing pad according to an embodiment of the present invention. This is a cross-sectional view showing an overview of a double-sided polishing apparatus. This is a plan view showing the lower platen of the double-sided polishing apparatus. This is a front view showing the upper platen and coolant supply section of the double-sided polishing apparatus, and a bottom view showing the polishing pad attached to the upper platen as seen from below. This is a photograph showing a partially enlarged view of a polishing pad according to an embodiment. This is a cross-sectional view showing an overview of a polishing pad according to a modified embodiment of the present invention.

[0023] Embodiments of the present invention will be described below with reference to the drawings.

[0024] -Structure of the polishing pad- Figures 1, 2, and 6 show a polishing pad 1 according to an embodiment of the present invention. This polishing pad 1 is disc-shaped and comprises a disc-shaped base material 2 on which an abrasive layer is formed on the surface side. For example, the outer diameter of the polishing pad 1 is 290 mm to 1500 mm, and the thickness is 1.0 mm to 3.5 mm.

[0025] The polishing layer has multiple (numerous) polishing sections 3 that are discretely and evenly spaced on the surface of the substrate 2. In Figures 1 and 2, the polishing sections 3 are depicted as large for simplification, but in reality, as shown in Figure 6, the polishing sections 3 are small compared to the overall size of the polishing pad 1. The polishing sections 3 have, for example, an outer diameter of 4 mm and a height of 0.9 mm. Numerous polishing sections 3 are provided on the upper surface of the substrate 2 at roughly equal intervals.

[0026] The polishing section 3 contains fillers such as alumina and silica, and abrasive particles such as diamond particles within a synthetic resin. The polishing section 3 itself is not translucent and is provided on the upper surface of the substrate 2 by methods such as coating.

[0027] The base material 2 is formed from at least one material selected from polycarbonate, polyvinyl chloride, and polyethylene terephthalate. The base material 2 has a thickness of, for example, 0.5 mm to 1.0 mm. The base material 2 only needs to have appropriate light transmission, but it is even better if it is colorless and transparent. Using these materials will provide a base material 2 that is readily available, highly transparent, and durable.

[0028] A disc-shaped support 4 may be provided on the back surface of the base material 2, which is bonded to the base material 2 via a first adhesive layer 5 and has a second adhesive layer 6 on its back surface.

[0029] The first adhesive layer 5, the second adhesive layer 6, and the support 4 are made of a light-transmitting material, but it is even better if they are colorless and transparent. For example, the first adhesive layer 5 and the second adhesive layer 6 are made of a pressure-sensitive adhesive with a thickness of 0.1 mm. By using an adhesive as the adhesive used in the adhesive layer, the polishing pad 1 can be easily peeled off the surface plate and replaced with a new polishing pad 1. Such adhesives are not particularly limited, but examples include acrylic adhesives, acrylic-rubber adhesives, natural rubber adhesives, synthetic rubber adhesives such as butyl rubber, silicone adhesives, polyurethane adhesives, epoxy adhesives, polyethylene adhesives, polyester adhesives, etc.

[0030] The support 4 is formed from, for example, at least one material selected from polycarbonate, polyvinyl chloride, and polyethylene terephthalate, which are light-transmitting or transparent and have a thickness of 0.5 mm to 2.0 mm.

[0031] In this embodiment, the visible light transmittance of the portion from the polishing section 3 to the second adhesive layer 6 is 30% or more.

[0032] As described above, if the portion from the base material 2 to the second adhesive layer 6 is made of a light-transmitting material, the light transmittance will be high. If the transmittance of visible light from the polishing section to the second adhesive layer is lower than 30%, it is not easy to confirm the coolant supply port 15, resulting in poor workability. However, by setting it to 30% or higher, the position of the coolant supply port 15 can be easily confirmed, resulting in good workability.

[0033] Furthermore, in the polished layer, the ratio of the area occupied by the polished portion 3 to the entire surface of the substrate 2 is between 26% and 60%.

[0034] If the aforementioned ratio is greater than 60%, the proportion of the non-transparent polishing area is too high, making it difficult to confirm the position of the coolant supply port 15. Conversely, if the aforementioned ratio is less than 26%, the proportion of the polishing area 3 is too low, making it impossible to ensure the intended polishing performance. Also, if the spacing between the polishing areas 3 becomes too wide, the workpiece to be polished may get caught and be damaged.

[0035] However, by setting the aforementioned ratio to 26% to 60%, the original polishing performance can be ensured while the position of the coolant supply port 15 can be easily confirmed, resulting in improved workability.

[0036] -Configuration of the double-sided polishing device- The polishing pad 1 of this embodiment is used, for example, in the double-sided polishing device 10 shown in Figure 3.

[0037] The double-sided polishing apparatus 10 has an upper platen 11 and a lower platen 12, both of which are rotatable and can move up and down relative to each other. The double-sided polishing apparatus 10 has a coolant supply unit 13 on the upper platen 11 side that can supply coolant. In this embodiment, since the polishing pad 1 contains abrasive grains, it is not necessary to include abrasive grains in the coolant. The coolant is circulated to the coolant supply unit 13 at an appropriate temperature by a recovery device (not shown), suppressing the generation of frictional heat and serving to collect polishing debris.

[0038] As shown in Figure 4, the second adhesive layer 6 of the polishing pad 1 is attached to the lower platen 12. Although not shown in detail, on the upper side of the lower platen 12, a plurality of annular carriers C made of synthetic resin or the like, each having external teeth on its outer circumference, are arranged to revolve and rotate at a predetermined rotational speed, meshing with the internal teeth of the gear of the lower platen 12 and the external teeth of the central axis, which are approximately the same diameter as the outer diameter of the polishing pad 1. A workpiece W such as a disc-shaped wafer or glass substrate is placed inside these carriers C.

[0039] As shown in Figure 5, multiple coolant supply pipes 14 extend from the coolant supply unit 13 and pass through the upper platen 11, and coolant can be supplied from the coolant supply ports 15 at their ends. The second adhesive layer 6 of the polishing pad 1 is attached to the lower surface of the upper platen 11, where multiple coolant supply ports 15 are opened.

[0040] Since the inner diameter, number, and position of the coolant supply ports 15 vary depending on the double-sided polishing device 10, it is undesirable to pre-form openings 7 in the polishing pad 1 to match the coolant supply ports 15, as this would limit the versatility of the polishing pad.

[0041] As shown in FIG. 3, the double-sided polishing apparatus 10 is configured to polish the upper and lower surfaces of the workpiece W provided in the carrier C with polishing pads 1 attached to the upper platen 11 and the lower platen 12, respectively.

[0042] - Polishing Pad Attachment Procedure - In order to use the polishing pad 1 in the double-sided polishing apparatus 10, first, it is necessary to attach the second adhesive layer 6 of the polishing pad 1 to the lower platen 12 and the upper platen 11.

[0043] When attaching the polishing pad 1 to the lower platen 12, the through-hole 1a in the center of the polishing pad 1 may be inserted through the central axis of the lower platen 12 for attachment, and the operation is easy.

[0044] Next, in order to attach the polishing pad 1 to the lower surface of the upper platen 11, since a plurality of coolant supply ports 15 are provided at multiple locations on this lower surface, if an opening 7 is not provided in the polishing pad 1 in accordance with the coolant supply ports 15, coolant cannot be supplied to the workpiece W side.

[0045] First, attach the second adhesive layer 6 to the lower surface of the upper platen 11 along its shape. Since the opening 7 is not provided in advance, the operation of aligning the coolant supply port 15 and the opening 7 is not necessary at this stage.

[0046] Next, with the polishing pad 1 attached, transmit visible light from the side of the coolant supply port 15. As the visible light, a commercially available LED white handlight or the like may be used. Visible light refers to light in the wavelength range of 380 nm to 780 nm as described in JIS B 7079. There is no need to use laser light or ultraviolet light for visual confirmation.

[0047] Then, confirm the position of the coolant supply port 15 by visible light that can be visually confirmed from the exposed base material 2 side.

[0048] With the position confirmed, form the opening 7 corresponding to the coolant supply port 15 from the polishing layer side using a power tool or the like from the lower side.

[0049] Thus, even if the position of the coolant supply port 15 in the double-sided inspection device differs for each model, when the polishing pad 1 is attached to the lower surface of the upper platen 11, an opening 7 corresponding to the coolant supply port 15 can be formed on the polishing pad 1 from below, so that the opening 7 is provided in the optimal position.

[0050] As described above, in this embodiment, since the polishing portion 3 contains abrasive grains, it has low transparency. By making the visible light transmittance of the area where the substrate 2 other than the polishing portion 3 is exposed 30% or more, with the second adhesive layer 6 attached to the lower surface of the upper platen 11 of the double-sided polishing device 10, visible light can be transmitted from the side of the coolant supply port 15 to confirm the position of the coolant supply port 15 from the polishing layer side, and an opening 7 corresponding to the coolant supply port 15 can be formed from the polishing layer side.

[0051] Therefore, with the polishing pad 1 according to this embodiment, the opening 7 can be easily made in line with the position of the coolant supply port 15 while the polishing pad 1 is attached to the upper platen 11.

[0052] -Modified Version- Figure 7 shows a polishing pad 101 according to a modified embodiment of the present invention, which differs from the above embodiment in that it does not have a support 4 and a second adhesive layer 6. The other structures are the same as in the above embodiment, so a detailed explanation is omitted.

[0053] - Procedure for attaching the polishing pad - In order to use the polishing pad 101 with the double-sided polishing device 10 as in the above embodiment, first, the first adhesive layer 5 of the polishing pad 101 is attached to the lower platen 12 and the upper platen 11.

[0054] When attaching the polishing pad 101 to the lower platen 12, the polishing pad 1 can be attached by inserting the through-hole 1a in the center of the polishing pad 1 through the central axis of the lower platen 12.

[0055] Next, in order to attach the polishing pad 101 to the lower surface of the upper platen 11, since there are multiple coolant supply ports 15 on this lower surface, an opening 7 must also be provided in the polishing pad 1 to match these coolant supply ports 15, otherwise coolant cannot be supplied to the workpiece W.

[0056] First, the first adhesive layer 5 is attached to the lower surface of the upper platen 11, conforming to its shape. Since the opening 7 has not been provided beforehand, there is no need to align the coolant supply port 15 with the opening 7 at this stage.

[0057] Next, with the polishing pad 101 attached, visible light is transmitted from the side of the coolant supply port 15.

[0058] Then, the position of the coolant supply port 15 is confirmed by visible light that can be visually inspected from the exposed substrate 2 side.

[0059] Once the position is confirmed, an opening 7 corresponding to the coolant supply port 15 is formed from the polishing layer side using a power tool or the like from below.

[0060] Thus, even if the position of the coolant supply port 15 in the double-sided inspection device differs for each model, when the polishing pad 101 is attached to the lower surface of the upper platen 11, an opening 7 corresponding to the coolant supply port 15 can be formed in the polishing pad 101 from below, so that the opening 7 is provided in the optimal position.

[0061] -Total light transmittance measurement- Measurements were taken using a turbidimeter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd., in accordance with JIS K 7361-1:1997. A D65 light source was used.

[0062] Diamond abrasive grains (median diameter approximately 30 μm) were prepared as abrasive particles, aluminum oxide grains (median diameter approximately 4 μm) as a filler, and epoxy resin as a binder. In addition, silica grains (median diameter approximately 1 μm) were prepared as other granular materials.

[0063] The abrasive grains, filler, binder, and other granular materials described above were mixed to prepare a polishing composition (coating liquid). The content of each material in the polishing composition was 5% by volume for abrasive grains, 60% by volume for filler, 30% by volume for binder, and 5% by volume for other granular materials.

[0064] A stainless steel mask was prepared, in which each polishing area was composed of a pattern of polishing layers with a diameter of 4 mm, an average thickness of 0.9 mm, and multiple polishing areas.

[0065] Multiple polishing areas were formed by coating a substrate with the above-mentioned polishing composition (coating liquid).

[0066] The polished area described above was circular in shape with a diameter of 4 mm in plan view, and had an average thickness of 0.9 mm. The multiple polished areas were arranged in a staggered pattern.

[0067] The above-mentioned polishing composition was cured by drying in an oven at 80-120°C for 16 hours or more to obtain a polishing layer substrate.

[0068] The above-mentioned polished substrate was cut into a circular shape with an outer diameter of 386 mm and an inner diameter of 148 mm, and attached to a support of the same shape using double-sided tape. The double-sided tape used was Sekisui Chemical Co., Ltd., #5605HGD, with an average thickness of 0.1 mm.

[0069] The substrate and support were selected from the following options: Substrate A: Sumitomo Bakelite, polycarbonate, EC105, average thickness 0.5 mm B: Sumitomo Bakelite, polycarbonate, EC105, average thickness 1.0 mm C: Sumitomo Bakelite, polycarbonate, ECG313C, average thickness 0.5 mm Support D: Sumitomo Bakelite, polycarbonate, EC105, average thickness 0.5 mm E: Takiron CI, rigid polyvinyl chloride resin sheet ET1980, average thickness 1.0 mm

[0070] - Evaluation of light transmission from the coolant supply port - The polishing pad was attached to the upper platen, and an LED light was shone from the coolant supply port. If the light was transmitted to the surface of the polishing pad and the location of the supply port could be confirmed, it was marked with ○; if it could not be confirmed, it was marked with ×.

[0071] - Polishing Feasibility Evaluation - The polishing pads of Example 1, Example 2, Example 3, Example 4, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were used to polish the glass material. A rough-surfaced glass substrate measuring 58 x 33 mm with an average thickness of 1.2 mm was used as the glass material.

[0072] A known double-sided polishing machine (Engis Japan Co., Ltd.: EJD-6BY) was used for the polishing described above. A glass epoxy with a thickness of 500 μm was used as the carrier for the double-sided polishing machine. The polishing pressure was 104 gf / cm². ２ That's what I decided.

[0073] Polishing was performed under the following conditions: upper platen rotation speed -30 rpm, lower platen rotation speed 60 rpm, and SUN gear rotation speed 8 rpm. Noritake Cool CG-50P (manufactured by Noritake), diluted 30 times with deionized water, was used as the coolant and supplied at a rate of 150 mL / min. A circle (○) was used if the glass substrate was successfully polished, and a cross (×) was used if polishing failed and the glass substrate cracked.

[0074]

[0075] The thickness was the total thickness of the sample for which the total light transmittance was measured, i.e., the sum of the polished portion 3, the substrate 2, the first adhesive layer 5, the support 4, and the second adhesive layer 6, and was measured with a micrometer.

[0076] In Example 1, when the base material 2 and support 4 were made of transparent polycarbonate, and the overall thickness of the polishing pad was set to 1.9 mm and the area occupied by the polishing portion 3 was set to 58%, making it equivalent to the polishing pad 1 of the above embodiment, the total light transmittance was 38.6%, and it was confirmed that the position of the coolant supply port 15 could be easily confirmed. Polishing work could also be performed without any problems.

[0077] In Example 2, when a polishing pad was manufactured in the same manner as in Example 1, with an overall thickness of 1.9 mm and a polishing area of ​​45%, the total light transmittance was 34.2%, and it was confirmed that the position of the coolant supply port 15 could be easily identified. Polishing work could also be performed without any problems.

[0078] In Example 3, when a polishing pad was manufactured in the same manner as in Example 1, with an overall thickness of 1.8 mm and a polishing area of ​​29%, the total light transmittance was 53.4%, and it was confirmed that the position of the coolant supply port 15 could be easily identified. Polishing work could also be performed without any problems.

[0079] Example 4 corresponds to a modification of the above embodiment. For example, a transparent polycarbonate with a thickness of 1 mm is used as the base material 2. The polishing area 3 is provided on the surface, and the first adhesive layer 5 is provided on the back surface. The total thickness of the polishing pad 1 is 2.2 mm, and the area occupied by the polishing area 3 is 38%. When the polishing pad 101 is made without the support 4 and the second adhesive layer 6, the total light transmittance is 49.3%, and it was confirmed that the position of the coolant supply port 15 can be easily confirmed. Polishing work could also be performed without any problems.

[0080] In Comparative Example 1, the base material 2 and support 4 were made of transparent polycarbonate, and the overall thickness of the polishing pad was set to 2.1 mm, with the polishing area occupied by the polishing portion being 18%, which is equivalent to the polishing pad 1 of the above embodiment. This resulted in a total light transmittance of 71.1%, and it was confirmed that the position of the coolant supply port 15 could be easily confirmed. However, because the area occupied by the polishing portion was small, the glass substrate got caught in the groove between the polishing portions, and the glass broke immediately after the rotational movement for polishing was started, making polishing impossible. It is desirable that the ratio of the area occupied by the polishing portion 3 to the entire surface of the base material 2 be in the range of 26% to 60%.

[0081] Comparative Example 2 is a modified version of the polishing pad 1 of the above embodiment, in which the support 4 is made of gray polyvinyl chloride, the base material 2 is made of white polycarbonate, and the polishing portion is laminated on the base material to make the overall thickness 2.6 mm. In Comparative Example 2, the total light transmittance was very low at 0.1%, and the position of the coolant supply port 15 was completely invisible.

[0082] Comparative Example 3 differs from Example 1 in that, when a polished area is created on the transparent polycarbonate, the polished area is provided so that the entire upper surface has irregularities, and the support 4 and the second adhesive layer 6 are not provided, so the transparent polycarbonate is not exposed. In this case, the total light transmittance decreases to 15.9%, making it difficult to confirm the position of the coolant supply port 15.

[0083] The embodiments described above are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

[0084] 1. Polishing pad 2. Base material 3. Polishing section (polishing layer) 4. Support 5. First adhesive layer 6. Second adhesive layer 7. Opening 10. Double-sided polishing device 11. Upper platen 14. Coolant supply pipe 15. Coolant supply port

Claims

1. A polishing pad comprising a disc-shaped base material, an abrasive layer formed on the surface side of the base material, and a first adhesive layer laminated on the back side of the base material, wherein the abrasive layer has a plurality of abrasive parts discretely and evenly spaced apart on the surface of the base material, the base material and the first adhesive layer are made of a light-transmitting material, and the visible light transmittance of the portion from the base material to the first adhesive layer in the region where the surface of the base material is exposed is 30% or more.

2. The polishing pad according to claim 1, comprising a disc-shaped support bonded to the back surface of the substrate via the first adhesive layer, and a second adhesive layer laminated on the back surface of the support, wherein the support and the second adhesive layer are made of a light-transmitting material, and the visible light transmittance of the portion from the substrate to the second adhesive layer in the region where the surface of the substrate is exposed is 30% or more.

3. The polishing pad according to claim 1 or 2, characterized in that the ratio of the area occupied by the polishing portion to the entire surface of the substrate in the polishing layer is 26% or more and 60% or less.

4. The polishing pad according to claim 1 or 2, characterized in that the substrate is formed from at least one selected from polycarbonate, polyvinyl chloride, and polyethylene terephthalate, which is permeable or transparent.

5. The polishing pad according to claim 1, characterized in that, with the first adhesive layer attached to the lower surface of the upper platen of the double-sided polishing device, visible light is transmitted from the side of the coolant supply port to confirm the position of the coolant supply port from the side of the polishing layer, and an opening corresponding to the coolant supply port is formed from the side of the polishing layer.

6. The polishing pad according to claim 2, characterized in that, with the second adhesive layer attached to the lower surface of the upper platen of the double-sided polishing device, visible light is transmitted from the side of the coolant supply port to confirm the position of the coolant supply port from the side of the polishing layer, and an opening corresponding to the coolant supply port is formed from the side of the polishing layer.

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