Polishing pad

Abstract

Provided is a polishing pad which is easy to bend and less likely to crack, for example, at the time of attachment to a surface plate.　This polishing pad comprises a base material layer, and a polishing layer which is arranged on the base material layer and contains a glycolic acid polymer and abrasive grains. The bending rigidity Fr per unit length of the polishing pad expressed by formula (1) at 25°C and 30%RH is 1.9 Pa m3 or less.　(1): Fr = E × h3 / 12 (In formula (1), E represents the flexural modulus (MPa) of the polishing pad, and h represents the thickness (mm) of the polishing pad).

Description

Polishing pad

[0001] This invention relates to a polishing pad.

[0002] In the power semiconductor field, insulated-gate bipolar transistor (IGBT) devices using silicon semiconductors have traditionally been used. In recent years, however, there has been a growing demand for high-current control in applications such as electric vehicles and power transmission, leading to a need for devices using compound semiconductors such as SiC semiconductors.

[0003] These wafers are typically polished or ground using free abrasive particles such as diamond abrasives. However, the number of free abrasive particles that work effectively relative to the amount used is small, which is one of the factors contributing to high costs.

[0004] In contrast, a method using a fixed abrasive type polishing pad containing a binder resin and abrasive grains fixed therein is also known. The applicants have proposed a fixed abrasive type polishing pad having glycolic acid polymer (PGA) and abrasive grains (see, for example, Patent Document 1). In a fixed abrasive pad having PGA and abrasive grains, the PGA becomes brittle and detaches due to hydrolysis when the abrasive grains wear down during polishing or grinding, making it easier to maintain a state where the abrasive grains protrude. Therefore, it is possible to suppress a decrease in polishing speed without dressing (sharpening).

[0005] International Publication No. 2024 / 248134

[0006] Incidentally, polishing pads are usually used while fixed to a surface plate called a lapping plate or platen. The polishing pad is usually fixed to the surface plate using an adhesive. If air bubbles get trapped between the polishing pad and the surface plate during fixing, it can cause uneven polishing, so it is desirable to bend the polishing pad while attaching it to the surface plate to prevent air bubbles from forming.

[0007] However, our investigations have revealed that, from the perspective of improving product life, if the thickness of the polishing layer in a polishing pad having a polishing layer containing PGA and abrasive grains is increased, it becomes difficult to bend when attaching it to a surface plate, and cracking may occur.

[0008] This invention has been made in view of the above circumstances, and aims to provide a polishing pad that is easy to bend and less prone to cracking when attached to a surface plate, for example.

[0009] This invention relates to the following polishing pad.

[0010] [1] A material comprising a base layer and an abrasive layer disposed on the base layer, the material having a bending stiffness Fr per unit length represented by formula (1) at 25°C and 30% RH, wherein ３ The polishing pad is as follows: Fr = E × h ３ / 12... Formula (1) (In Formula (1), E represents the flexural modulus of the polishing pad (MPa), and h represents the thickness of the polishing pad (mm)) [2] The polishing pad according to [1], wherein when one end of the polishing pad is bonded to the base via adhesive, the lifting force required to maintain the other end of the polishing pad at a height of 30 mm from the base is 50.0 N or less. [3] The polishing pad according to [1] or [2], wherein the content of the abrasive grains in the polishing layer is 1% by mass or more and 55% by mass or less with respect to the total mass of the polishing layer. [4] The polishing pad according to any one of [1] to [3], wherein the thickness of the polishing layer is 1.0 mm or more and 50 mm or less. [5] The polishing pad according to any one of [1] to [4], wherein the polishing layer has an uneven shape with a plurality of protrusions. [6] The polishing pad according to [5], wherein, of the polishing layer, when the sum of the horizontal projected areas of the plurality of protrusions is S1 and the sum of the horizontal projected areas of the recessed portions excluding the plurality of protrusions is S2, S2 / S1 is 1.3 or less. [7] The polishing pad according to [5] or [6], wherein, of the thickness of the polishing layer, the thickness of the recessed portions formed around the protrusions is 60% or less of the thickness of the polishing layer. [8] The polishing pad according to any one of [1] to [7], wherein the tensile modulus of the base layer is lower than the tensile modulus of the glycolic acid polymer, and when the thickness of the base layer is T1 and the thickness of the polishing layer is T2, T1 / T2 is 0.02 or more and 1.0 or less. [9] The polishing pad according to any one of [1] to [8], wherein the base layer includes a polyolefin film, a polyester film, or a polycarbonate film.

[0011] According to the present invention, it is possible to provide a polishing pad that is easy to bend and less prone to cracking, for example, when attaching it to a surface plate.

[0012] Figures 1A and 1B are explanatory diagrams showing how to cut out a test piece when the polishing pad has an uneven shape. Figure 2A is a schematic plan view showing a polishing pad according to one embodiment of the present invention, and Figure 2B is a schematic partial cross-sectional view taken along line 2B-2B of Figure 2A. Figure 3A is a schematic partially enlarged plan view of the polishing pad of Figure 2A, and Figure 3B is a schematic partially enlarged plan view of a polishing pad according to another embodiment. Figures 4A and 4B are schematic diagrams showing a method for measuring lifting force. Figure 5 is a schematic diagram showing a polishing apparatus.

[0013] One embodiment of the present invention will be described in detail below. However, the present invention is not limited to this embodiment. Furthermore, in this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower limit and upper limit.

[0014] 1. Polishing Pad: The polishing pad comprises a base layer and an polishing layer. The polishing pad may further have other layers, such as an adhesive layer, as needed.

[0015] One indicator of how easily something can be bent is its bending stiffness. The bending stiffness of a polishing pad can be calculated based on the second moment of area for a rectangular cross-section, since the cross-section of the polishing pad when cut perpendicular to the polishing surface is rectangular. Here, the second moment of area (I) for a rectangular cross-section is given by I = b × h, where b is the width of the polishing pad's cross-section and h is the thickness of the pad. ３ It is expressed as / 12. Therefore, the bending stiffness of the polishing pad is given by E × b × h, where E is the bending modulus of the polishing pad, b is the width of the cross-section of the polishing pad, and h is the thickness of the polishing pad. ３represented by / 12. This value varies depending on the size, shape, adhesive area, etc. of the sample. Regardless of the size, shape, adhesive area, etc. of the sample, the present inventors adopted a value obtained by dividing flexural rigidity by the cross-sectional width b of the polishing pad as an index representing the bendability of the sample itself, and found "flexural rigidity per unit length (Fr)" represented by the following formula (1). Fr=EI / b=E×h ３ / 12 --- Formula (1) (In Formula (1), E represents the flexural modulus of the polishing pad (MPa), and h represents the thickness of the polishing pad (mm))

[0016] According to studies conducted by the present inventors, it has been found that when the flexural rigidity per unit length of the polishing pad is not more than a certain value, the polishing pad is easily bent and less likely to crack when attached to a surface plate. That is, the flexural rigidity per unit length (Fr) represented by formula (1) of the polishing pad at 25°C and 30% RH is 1.9 Pa·m ３ or less, preferably 0.05 Pa·m ３ or more and 1.8 Pa·m ３ or less, more preferably 0.1 Pa·m ３ or more and 1.4 Pa·m ３ or less, still more preferably 0.2 Pa·m ３ or more and 1.0 Pa·m ３ or less. Note that E (MPa = N / mm ２ ), h ３ (mm ３ ), so E×h ３ can be converted as N·mm = (Pa·m ２ ) × 0.001 m.

[0017] The flexural modulus of the polishing pad can be measured in accordance with JIS K7074:1988. (1) Preparation of the test specimen Specifically, the polishing pad is cut to 105 mm x 15 mm to make a test specimen. However, if the polishing pad has through holes, it is preferable to cut the test specimen while avoiding the through holes. Also, if the polishing pad has an uneven shape, the test specimen is cut from the polishing pad such that the center line passing through the center in the direction of the long side and its extension line are in a position corresponding to the concave part (a position that does not overlap with the convex part as much as possible). In this case, it is preferable to cut the test specimen so that the direction of the short side of the test specimen (the direction in which the test specimen is bent) coincides with the direction in which the concave parts of the polishing pad are connected in a straight line. Figures 1A and 1B are explanatory diagrams of how to cut a test specimen when the polishing pad has an uneven shape. In these figures, the gray parts are convex parts and the colorless parts are concave parts. For example, in the same figure, test specimen a is in a position where the center line (dashed line) and its extension line correspond to the concave part and do not overlap with the convex part, so it is preferable. On the other hand, test piece b is undesirable because its center line or its extension overlaps with the convex portion.

[0018] (2) Bending test A bending test is performed on this specimen in accordance with JIS K7074:1988, with a support distance of 80 mm and a crosshead speed of 5 mm / min. The bending modulus is calculated from the obtained displacement and load. A known material testing machine (for example, the Tensilon universal material testing machine RTF-2350 manufactured by A&D Company, Limited) can be used as the measuring device. Measurements are performed with n=3, and the average value of these measurements is taken as the bending modulus.

[0019] The thickness of the polishing pad can be measured using a micrometer (for example, a Mitutoyo PMU300-25MB U-shaped steel plate micrometer) to measure the total thickness of the polishing pad excluding the release film. However, if the polishing pad has an uneven shape, the thickness of the polishing pad should be measured only in the areas with protrusions. Alternatively, the distance from the center O of the polishing pad surface to the edge should be set to 1, a circle with a radius of 0.6 should be drawn from the center O, and the circumference of this circle should be divided into 10 equal parts. Each of these 10 points on the circumference should be used as a measurement point. The average value of these 10 points should be calculated and used as the thickness of the polishing pad.

[0020] The bending rigidity mentioned above depends on the uneven shape of the polished layer (for example, the thickness of the recessed portion (t)). ２１), height of the protrusion (t ２２ The thickness can be adjusted by the following: the thickness of the protrusions and their ratios, the minimum spacing between protrusions (w), and the ratio of the total horizontal projection area S1 of the multiple protrusions to the horizontal projection area S2 of the remaining parts (S2 / S1), etc., as well as the abrasive content of the polishing layer, the type and thickness of the base layer, etc. For example, if the polishing layer has an uneven shape, the thickness of the recessed portion of the polishing layer (t ２１ The bending rigidity tends to decrease if the ratio of the protrusions (T1) is reduced, the minimum distance between the protrusions (w) is increased, or S2 / S1 is increased. Also, the bending rigidity tends to decrease if the thickness of the base layer or polishing layer is reduced, or if the ratio of the thickness of the base layer T1 to the thickness of the polishing layer T2 (T1 / T2) is increased. Furthermore, the bending rigidity tends to decrease if the abrasive grain content of the polishing layer is reduced.

[0021] An embodiment of the polishing pad will be described below with reference to the drawings.

[0022] Figure 2A is a schematic plan view showing an example of a polishing pad 100, and Figure 2B is a schematic partial cross-sectional view taken along line 1B-1B in Figure 2A. Figure 3A is a schematic partially enlarged plan view of the polishing pad of Figure 2A, and Figure 3B is a schematic partially enlarged plan view of a polishing pad according to another embodiment. In Figures 3A and 3B, hatching is applied to the recessed portion 122 to clearly show the convex portion 121.

[0023] As shown in Figure 2B, the polishing pad 100 has a base layer 110, a polishing layer 120, a first adhesive layer 130A, and a second adhesive layer 130B.

[0024] 1-1. Base Layer 110 The base layer is not particularly limited as long as the bending stiffness per unit length of the polishing pad satisfies the above range, but it is preferably a resin film.

[0025] Preferably, the resin film is formed of a resin material having a lower tensile modulus of elasticity than the glycolic acid polymer contained in the polishing layer. Further, when the polishing pad further includes an adhesive layer, a resin material having a higher tensile modulus of elasticity than the material of the adhesive layer is preferred. Examples of such a resin material include resin materials having a tensile modulus of elasticity of 1 MPa or more and 5000 MPa or less, preferably 10 MPa or more and 4000 MPa or less. The tensile modulus of elasticity of the resin material can be measured in accordance with ISO 527.

[0026] Examples of resin films formed of such resin materials include polyester films such as polyethylene terephthalate films, polypropylene terephthalate films, and polybutylene terephthalate films; polyolefin films such as polyethylene (PE) films, polypropylene (PP) films, and ethylene-propylene copolymer films; films of elastomer materials including polycarbonate (PC) films, polyether ether ketone (PEEK) films, polyphenylene sulfide (PPS) films, silicone rubber, fluororubber, urethane rubber, natural rubber, isoprene rubber, ethylene propylene rubber, butyl rubber, styrene rubber, acrylic rubber, aliphatic polyester rubber, chloroprene rubber, polyester-based thermoplastic elastomers and polyamide-based thermoplastic elastomers, and ionomer resin films using ethylene-based, styrene-based, urethane-based, fluorine-based polymers, etc. Among these, from the viewpoint of low modulus of elasticity and easier bending of the polishing pad, polyolefin films, polyester films and polycarbonate films are preferred, polyolefin films are more preferred, and polyethylene films are even more preferred.

[0027] The flexural modulus of the base material layer 110 is not particularly limited, but from the viewpoint of further reducing the flexural rigidity per unit length of the polishing pad 100, the flexural modulus is preferably lower than that of the polishing layer 120. The flexural modulus of the base material layer 110 is, for example, preferably 300 MPa or more and 4000 MPa or less. The flexural modulus of the base material layer 110 can be measured by the same method as described above.

[0028] The thickness of the base material layer is not particularly limited, but from the viewpoint of improving work stability during polishing, it is preferably equal to or thinner than the thickness of the polishing layer. When the thickness of the base material layer is T1 and the thickness of the polishing layer is T2, T1 / T2 is preferably 0.02 or more and 1.0 or less, more preferably 0.1 or more and 0.8 or less. When T1 / T2 is 0.02 or more, the flexural rigidity per unit length of the polishing pad can be further reduced, making the polishing pad more flexible. When T1 / T2 is 1.0 or less, the hardness of the entire polishing pad can be further increased. Thereby, when the polishing pad is brought into contact with the object to be polished and a load is applied, the abrasive grains exposed on the surface are less likely to be pushed back to the base material, and the polishing performance can be further improved. The thickness of the base material layer is, for example, preferably 0.1 mm or more and 1.0 mm or less, more preferably 0.3 mm or more and 0.8 mm or less.

[0029] The thickness of the base material layer can be measured with a digital microscope (for example, VHX-X1 manufactured by Keyence Corporation). Specifically, first, a polishing pad is cut into a 5 mm × 5 mm square using a cutter or the like. Thereafter, a microtome is used to prepare the cross section so that it can be easily observed. The obtained cross section is observed with a digital microscope, and the measurement is performed by measuring the length of the base material layer portion.

[0030] 1-2. Polishing layer 120 The polishing layer comprises a glycolic acid polymer and abrasive grains.

[0031] 1-2-1. Glycolic acid polymer The glycolic acid polymer is a structural unit derived from glycolic acid (-(-O-CH ２This polymer is mainly composed of -CO-)-). Being mainly composed of constituent units derived from glycolic acid means that the content of constituent units derived from glycolic acid is 50% by mass or more of the total amount of constituent units constituting the glycolic acid polymer. The content of constituent units derived from glycolic acid is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. When the above content of constituent units derived from glycolic acid is 50% by mass or more, the strength of the glycolic acid polymer increases, thus increasing the strength of the polishing layer. Furthermore, because the hydrolysis of the glycolic acid polymer proceeds more easily, the decrease in polishing speed can be reduced.

[0032] The glycolic acid polymer may be a homopolymer of glycolic acid, or a copolymer of glycolic acid and a monomer copolymerizable thereto.

[0033] Examples of copolymerizable monomers include glycols such as ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; dicarboxylic acids such as oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanediic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, bis(p-carboxyphenyl)methane, anthracenedicarboxylic acid, 4,4'-diphenyl etherdicarboxylic acid, 5-sodium sulfisoisophthalic acid, and 5-tetrabutylphosphonium isophthalic acid; hydroxycarboxylic acids such as lactic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, and hydroxybenzoic acid; and lactides. This includes lactones such as caprolactone, valerolactone, propiolactone, undecalactone, and 1,5-oxepant-2-one; and carbonates such as trimethylene carbonate.

[0034] Among these, glycolic acid homopolymers are preferred from the viewpoint of having higher strength and being easily hydrolyzable.

[0035] The weight-average molecular weight of the glycolic acid polymer is not particularly limited, but it is preferably between 70,000 and 500,000. When the weight-average molecular weight of the glycolic acid polymer is 70,000 or more, the strength of the glycolic acid polymer can be increased, and thus the strength of the polishing layer can be increased. In addition, when a polishing pad is brought into contact with the workpiece and a load is applied, the abrasive grains exposed on the surface are less likely to be pushed back into the base material, thus reducing the decrease in polishing speed. When the weight-average molecular weight of the glycolic acid polymer is 500,000 or less, not only is the moldability increased, but the time until it disintegrates due to hydrolysis can be shortened. From a similar viewpoint, the weight-average molecular weight of the glycolic acid polymer is more preferably between 110,000 and 400,000.

[0036] The weight-average molecular weight of glycolic acid polymers can be measured by gel permeation chromatography (GPC). The measurement conditions are as follows: (Measurement conditions) Apparatus: Showa Denko "Shodex-104" Column: Two HFIP-606M columns connected in series with one HFIP-G column as a pre-column Column temperature: 40°C Eluent: HFIP (hexafluoro-2-propanol) solution in which 5 mM sodium trifluoroacetate is dissolved Flow rate: 0.6 mL / min Detector: RI (differential refractive index) detector Molecular weight calibration: Five types of standard polymethyl methacrylate with different molecular weights

[0037] The glycolic acid polymer content is preferably 20% to 98.5% by mass, more preferably 50% to 94% by mass, and even more preferably 70% to 89% by mass, relative to the total mass of the polishing layer. When the glycolic acid polymer content is 20% by mass or more, not only is the strength of the polishing layer increased, but new abrasive grains are more easily exposed by hydrolysis of the glycolic acid polymer, further promoting the replacement of the surface. When the glycolic acid polymer content is 98.5% by mass or less, the proportion of abrasive grains is above a predetermined level, so the polishing speed can be increased.

[0038] 1-2-2. Abrasive grains The material of the abrasive grains is not particularly limited, but examples include diamond, silicon carbide, boron carbide, boron nitride, silicon nitride, cerium oxide, aluminum oxide, zirconium oxide, silicon oxide, iron oxide, manganese oxide, magnesium oxide, calcium oxide, barium oxide, zinc oxide, titanium oxide, chromium oxide, barium carbonate, and calcium carbonate. Among these, diamond, boron carbide, and boron nitride are preferred from the viewpoint of increasing the polishing speed, and diamond is more preferred from the viewpoint of making it easier to process substrates with high hardness such as SiC substrates.

[0039] The upper limit of the median diameter of the abrasive grains depends on the desired degree of polishing, but is preferably 0.01 μm or more and 50 μm or less, more preferably 0.1 μm or more and 30 μm or less, and even more preferably 0.2 μm or more and 15 μm or less. When the median diameter of the abrasive grains is 0.01 μm or more, the polishing speed can be increased. Also, when the median diameter of the abrasive grains is 50 μm or less, the surface roughness of the workpiece can be improved.

[0040] The median diameter of abrasive grains can be determined from the particle size distribution measured according to particle size analysis - laser diffraction and scattering method (ISO 13320:2020). Specifically, it can be measured using a laser diffraction particle size analyzer (e.g., Malvern Mastersizer 3000) under the following conditions: measurement temperature of 21°C, dispersion medium of deionized water, dispersion medium refractive index of 1.330, and light scattering model of Mie theory. Abrasive grains can be obtained by heating and melting the abrasive layer, passing the resulting molten material through a filter, and separating the abrasive grains from other components (glycolic acid polymer, etc.).

[0041] The abrasive content is not particularly limited, but is preferably 1% to 55% by mass relative to the total mass of the polishing layer, more preferably 3% to 40% by mass, even more preferably 5% to 30% by mass, and particularly preferably 5% to 20% by mass. When the abrasive content is 1% by mass or more, the polishing speed can be increased. When the abrasive content is 55% by mass or less, the moldability or machinability of the polishing pad can be increased.

[0042] The abrasive content can be measured using a thermogravimetric analysis (TGA) apparatus. Specifically, on the surface of the polishing layer of an unused polishing pad, let L be an arbitrary straight line passing through the center O of the polishing layer, and let M be a straight line perpendicular to L and passing through the center O of the polishing layer. Let a1 and a2 be the midpoints between the center O and the edge of the polishing layer on line L, and b1 and b2 be the midpoints between the center O and the edge of the polishing layer on line M. Take a sample of 100 mg or more from the polishing layer from each measurement point, within the range including each measurement point O, a1, a2, b1, and b2, and crush it as appropriate to obtain the measurement sample from each measurement point. Place 20 mg ± 2 of the measurement sample in a platinum pan, heat it from room temperature at a rate of 10°C / min to 800°C in an air atmosphere, hold it at 800°C for 30 minutes to burn off components other than abrasive grains, and divide the remaining sample weight by the mass of the measurement sample to determine the abrasive content in the polishing layer at each measurement point. In this application, the arithmetic mean of the abrasive content of each of the five points described above is used as a representative value for the abrasive content of the polishing layer.

[0043] 1-2-3. Shape or Physical Properties of the Polishing Layer From the viewpoint of making the polishing layer 120 easier to bend, it is preferable that the polishing layer 120 has an uneven shape with a plurality of protrusions 121. That is, it is preferable that the surface of the polishing layer 120 has an uneven surface with parts that contact the workpiece to be polished (a plurality of protrusions 121) and parts that do not contact the workpiece to be polished (recessed parts 122 formed around the protrusions 121) (see Figures 2A to 3B). By having an uneven shape, the flexibility of the polishing layer 120 can be increased, making it easier to bend.

[0044] The protrusions 121 may be ridges or island-shaped protrusions. For example, in the polishing layer 120, multiple ridges may be arranged in parallel, multiple ridges may be arranged concentrically, or multiple island-shaped protrusions may be arranged in a matrix or randomly (see Figures 3A and 3B).

[0045] The three-dimensional shape of the island-like protrusion 121 is not particularly limited and may be columnar (cylindrical, roughly cylindrical, elliptical, roughly elliptical, polygonal prism) or frustoconical (frustoconical, roughly frustoconical, elliptical, roughly elliptical, polygonal frustoconical). In Figure 3A, it is a rectangular prism, and in Figure 3B, it is cylindrical.

[0046] The distance between the centers of the multiple protrusions 121 (pitch p) is not particularly limited, but is preferably 2 mm to 20 mm, more preferably 3 mm to 15 mm, and even more preferably 4 mm to 10 mm. If the distance between the centers of the multiple protrusions 121 is 2 mm or more, the proportion of the effective polishing area increases, thus improving polishability. If the distance between the centers of the multiple protrusions 121 is 20 mm or less, the proportion of the recessed portion 122 formed around the protrusions 121 increases, making the polished layer 120 easier to bend. Note that the distance between the centers of the multiple protrusions 121 refers to the minimum distance between the centers of the multiple protrusions 121 (see Figures 3A and 3B).

[0047] Height of the protrusion 121 (t ２２ The thickness of the polishing layer 120 is preferably 30% to 98%, and more preferably 40% to 90%, of the thickness T2 of the polishing layer 120 (see Figure 2B). The height of the protrusion 121 is preferably 0.3 mm to 20 mm, and more preferably 0.5 mm to 10 mm. That is, the thickness of the recessed portion 122 formed around the protrusion 121 is the thickness of the polishing layer 120 (t ２１The thickness of the recessed portion 122 is preferably 60% or less of the thickness T2 of the polishing layer 120, more preferably 1% to 50%, and even more preferably 10% to 50% (see Figure 2B). If the thickness of the recessed portion 122 is 60% or less, the thickness of the recessed portion 122 becomes thinner, which increases the flexibility of the polishing layer 120 and makes it easier to bend. If the thickness of the recessed portion 122 is 1% or more, the convex portions 121 are less likely to come into contact with each other when the polishing pad is bent, making the polishing layer 120 less likely to be damaged. The thickness of the recessed portion 122 of the polishing layer 120 is preferably, for example, 0 mm to 1.5 mm, more preferably 0.1 mm to 1 mm, even more preferably 0.1 mm to 0.65 mm, and particularly preferably 0.1 mm to 0.6 mm. The first adhesive layer 130A or the base material layer 110 may or may not be exposed in the recessed portion 122.

[0048] The minimum spacing (w) between adjacent protrusions 121 is not particularly limited, but is preferably 5% to 50% of the distance between the centers of the multiple protrusions 121, and more preferably 7% to 30% (see Figures 3A and 3B). If the minimum spacing is 5% or more of the distance between the centers, it can be made easier to bend. If the minimum spacing is 50% or less of the distance between the centers, the proportion of the effective polishing area can be increased, and thus polishability can be further improved. For example, the minimum spacing is preferably 0.1 mm to 5 mm, more preferably 0.5 mm to 3 mm, and more preferably 0.5 mm to 2 mm. Note that if the three-dimensional shape of the protrusions 121 is frustum-shaped, the minimum spacing (w) means the distance between the top surfaces of adjacent protrusions 121.

[0049] The thickness of the polishing layer 120 is not particularly limited as long as the bending stiffness per unit length of the polishing pad 100 falls within the above range. Preferably, the thickness of the polishing layer satisfies the above range of T1 / T2, for example, preferably 1.0 mm or more and 50.0 mm or less, and more preferably 1.5 mm or more and 40.0 mm or less. If the thickness of the polishing layer is 1.0 mm or more, the overall hardness of the polishing pad can be increased. Therefore, when the polishing pad is brought into contact with the workpiece and a load is applied, the abrasive grains exposed on the surface are less likely to be pushed back into the base material, thus reducing the decrease in polishing speed. In addition, the usage time can be extended. On the other hand, if the thickness of the polishing layer is 50.0 mm or less, the bending stiffness per unit length of the polishing pad can be lowered, making it easier to bend. Note that the thickness of the polishing layer 120 (T2) refers to the thickness of the portion of the polishing layer 120 having the protrusions 121 (see Figure 2B). The thickness of the polishing layer can be measured in the same way as the thickness of the base layer.

[0050] In the polishing layer 120, when S1 is the sum of the horizontal projected areas of the multiple protrusions 121 and S2 is the sum of the horizontal projected areas of the recessed portions 122 excluding the multiple protrusions 121, S2 / S1 is preferably 1.3 or less, more preferably 0.1 to 1, and even more preferably 0.2 to 0.8. When S2 / S1 is 1.3 or less, the proportion of the effective polishing area increases, thus improving polishability. When S2 / S1 is 0.1 or more, the proportion of the recessed portions 122 increases, making the polishing layer 120 easier to bend.

[0051] Height (t) of the protrusion 121 of the polished layer ２２The center-to-center distance (p), minimum interval (w), and S2 / S1 can be measured using a 3D scanner (for example, Keyence's VR-5000 one-shot 3D shape measuring machine). Specifically, a region containing one or more repeating units of the uneven shape is observed using a 3D scanner. Next, a plane is estimated for the entire observation field using the least squares method, and a reference plane is set. For convenience, the reference plane is positioned between the plane containing the top surface of the convex portion 121 and the plane containing the bottom surface of the concave portion (recessed portion 122). Next, the entire height data is rotated so that the reference plane is horizontal, and adjusted so that the height of the reference plane is 0. These adjustments can be performed using the analysis application attached to the 3D scanner. Subsequently, for each repeating unit of the uneven shape, the region higher than the height threshold of the reference plane (i.e., 0 mm) is defined as the region corresponding to the convex portion, and the region lower than the height of the reference plane is defined as the region corresponding to the concave portion. By measuring the area of ​​each region, S1 and S2 can be measured, and S2 / S1 can be calculated. Furthermore, for each repeating unit of the uneven shape, t ２２、 p and w are each measured at four points, and their average values ​​are used as representative values. ２２ This can be determined by adding the height from the reference plane to the top of the convex part and the depth from the reference plane to the bottom of the concave (recessed) part.

[0052] The flexural modulus of the polishing layer 120 is not particularly limited, but is preferably 3 GPa or more and 20 GPa or less, and more preferably 5 GPa or more and 18 GPa or less. The lower the flexural modulus of the polishing layer 120, the lower the bending stiffness per unit length of the polishing pad 100 can be. Also, the higher the flexural modulus of the polishing layer 120, the higher the overall hardness of the polishing pad can be. Therefore, when the polishing pad is brought into contact with the workpiece and a load is applied, the abrasive grains exposed on the surface are less likely to be pushed back by the base material, thus reducing the decrease in polishing speed. The flexural modulus of the polishing layer 120 can be measured by the same method as described above.

[0053] 1-3. First adhesive layer 130A, second adhesive layer 130B The first adhesive layer 130A is a layer for bonding the base layer 110 and the polishing layer 120, and is positioned between the base layer 110 and the polishing layer 120. The second adhesive layer 130B is a layer for attaching the polishing pad to the polishing platen of the polishing machine, and is positioned on the opposite side of the polishing layer 120 from the base layer 110.

[0054] The first adhesive layer 130A and the second adhesive layer 130B each contain an adhesive or adhesive agent. The adhesive or adhesive agent may be one of those used in known polishing pads, and examples include thermoplastic adhesives such as vinyl acetate adhesives, vinyl acetate-vinyl chloride copolymer adhesives, polyvinyl butyral adhesives, polyamide adhesives, and polyolefin adhesives; rubber adhesives such as natural rubber adhesives, synthetic rubber (nitrile rubber, etc.) adhesives, silicone rubber adhesives, thiocol rubber adhesives, and butyl rubber adhesives; thermosetting adhesives such as polyurethane resin adhesives, polyester resin adhesives, phenolic resin adhesives, epoxy resin adhesives, polyimide resin adhesives, polyvinyl-phenolic resin adhesives, neoprene-phenolic resin adhesives, nitrile-phenolic resin adhesives, nylon-epoxy resin adhesives, and epoxy-phenolic resin adhesives; cyanoacrylate adhesives; and acrylate adhesives. Furthermore, the first adhesive layer 130A and the second adhesive layer 130B may be, for example, double-sided tapes having an adhesive layer / base material / adhesive layer structure. The base material may be the same as the material of the base layer described above, and may be, for example, a polyolefin film.

[0055] The thicknesses of the first adhesive layer 130A and the second adhesive layer 130B are not particularly limited, but are preferably 0.01 mm or more and 0.25 mm or less, and more preferably 0.05 mm or more and 0.2 mm or less. The thickness of each adhesive layer can be measured in the same way as the thickness of the substrate layer.

[0056] 1-4. Polishing pads other than those described above may further have other layers. For example, polishing pad 100 may further have a release film (not shown) to protect the second adhesive layer 130B. When using polishing pad 100, the release film should be peeled off and the exposed second adhesive layer 130B should be attached to the platen of the polishing machine.

[0057] 1-5. Physical properties of the polishing pad (lifting force) The lifting force required to bond one end of the polishing pad to the base via an adhesive layer and maintain the other end lifted to a height of 30 mm from the base is preferably 50.0 N or less, more preferably 0.1 N to 40.0 N, even more preferably 0.1 N to 35.0 N, and even more preferably 0.1 N to 30.0 N.

[0058] The bending stiffness Fr per unit length described above can be used to evaluate the ease of bending the polishing pad, regardless of the size of the polishing pad or the bonding area. On the other hand, even if the bending stiffness Fr per unit length is the same, the smaller the size of the polishing pad, the greater the force required to lift the end of the polishing pad. If the above lifting force is preferably 50.0 N or less, the polishing pad can be bent more easily and less prone to cracking when attached to the surface plate.

[0059] The lifting force of the polishing pad can be measured by the following method: 1) A φ5 mm hole 1 is made 25 mm from the end of the polishing pad 100 on the center line L1 passing through the center O (see Figure 4A). At this time, the polishing pad 100 used for measurement is the one before the through hole for attachment to the polishing device is formed. The other end of the polishing pad 100 on the center line L1 is bonded to the base 2 via adhesive (for example, the second adhesive layer 130B in Figure 2B) (see Figure 4B). At this time, the length of the bonded part 3 on L1 is bonded so that it is 3 / 4 the length of the diameter of the polishing pad 100 (see Figure 4A). 2) Next, a spring scale 4 is hooked into the hole 1 formed in the polishing pad 100 and pulled up (see Figure 4B). The lifting force is measured from the reading on the spring scale 4 when it is lifted 30 mm from the top surface of the base 2. Furthermore, if the polished layer has an uneven shape, ensure that the end of the adhesive portion 3 (L2 in Figure 4A) does not overlap with the position of the protrusion 121. If it is impossible to avoid overlapping with the protrusion 121 regardless of how the direction is adjusted, reduce the size of the protrusion 121 as much as possible.

[0060] The lifting force can be adjusted in the same way as the bending stiffness per unit length described above (such as the uneven shape of the polishing layer, the thickness of the polishing layer, the abrasive content, the type and thickness of the base layer, etc.). In addition, the lifting force can also be adjusted by the size of the polishing pad and the formation of through holes. For example, the smaller the size of the polishing pad, the greater the lifting force tends to be. Furthermore, polishing pads that have been processed by forming through holes in the center or elsewhere to attach them to the polishing device tend to have a smaller lifting force and are easier to bend.

[0061] Furthermore, the bending stiffness (Fr) per unit length of the polishing pad is 0.1 Pa·m. ３ 0.9Pa・m or more ３ Preferably, the lifting force is between 0.1 N and 50.0 N; and the bending stiffness per unit length (Fr) is 0.2 Pa·m. ３ 0.9Pa・m or more ３ The following is preferable, and it is even more preferable that the lifting force is between 0.1 N and 25.0 N. This makes it easier to bend and less prone to cracking when attaching it to a surface plate, etc.

[0062] 2. Method for Manufacturing Polishing Pads Polishing pads can be manufactured by any method. For example, a polishing pad can be manufactured by a process of preparing an polishing sheet (polishing sheet preparation process) and a process of laminating and bonding a base material and a polishing sheet (lamination and bonding process).

[0063] 2-1. Preparation of Polishing Sheets Polishing sheets can be prepared by any method. For example, a polishing sheet as shown in Figure 2 can be prepared by the following steps: 1) obtaining a composition containing glycolic acid polymer and abrasive grains, 2) molding the obtained composition, and 3) forming irregularities on the surface of the molded body.

[0064] In step 1), for example, a composition containing a glycolic acid polymer and abrasive grains can be obtained by kneading the glycolic acid polymer and abrasive grains under heating. As a kneader, for example, a roll kneader, a Banbury mixer, an extruder (single-screw, multi-screw), etc. can be used.

[0065] The heating temperature can be, for example, 150°C to 270°C. In particular, if the composition contains a hydrolysis accelerator, the heating temperature is preferably such that the hydrolysis accelerator can be dispersed in a stable state. The form of the composition is not particularly limited and may be, for example, pelletized, powdered, or filamentous.

[0066] In step 2), the obtained composition is molded into a predetermined shape to form an abrasive sheet. The molding method is not particularly limited and may be any of the following: injection molding, melt extrusion molding, solidification extrusion molding, vacuum molding, transfer molding, or compression molding. Molding may also be performed using a 3D printer.

[0067] When manufacturing a molded body by compression molding, pellets of the above composition are supplied into the mold. The mold temperature is then set to 150°C to 270°C, and a polished sheet can be obtained by press molding.

[0068] In step 3), irregularities are formed on the surface of the obtained molded body. The method of forming the irregularities is not particularly limited; they may be formed by cutting the surface of the molded body of the composition, or by molding the composition using a mold or template that has a pattern corresponding to the irregularity pattern formed on it. Note that the step of forming irregularities on the surface of the molded body may be performed after the lamination and bonding steps described later.

[0069] In addition to steps 1) to 3) above, the process may further include a processing step to make the thickness of the abrasive sheet uniform. Specifically, the variation in the thickness of the abrasive sheet can be reduced to below a certain value by cutting, sandpaper polishing, buffing, etc.

[0070] 2-2. Lamination and Bonding Process A polishing pad can be obtained by laminating and bonding the prepared polishing sheet and the base sheet.

[0071] The abrasive sheet and the base sheet can be bonded together by any method. The abrasive pad shown in Figure 2 can be obtained by laminating and bonding the abrasive sheet and the base sheet together using an adhesive or bonding agent.

[0072] For example, an adhesive or tack can be applied to both sides of a base sheet and then dried, or double-sided tape can be attached to both sides of the base sheet to obtain an adhesive-coated base sheet having adhesive layers on both sides. By laminating this adhesive-coated base sheet and an abrasive sheet using a laminator (such as a heat-seal film laminator manufactured by MCK Corporation), an abrasive pad having a laminated structure as shown in Figure 2 can be obtained.

[0073] 3. Polishing Method of the Workpiece Figure 5 is a schematic diagram showing the configuration of the polishing apparatus 200. Detailed illustration of the polishing pad 100 is omitted in this figure.

[0074] As shown in Figure 5, the polishing apparatus 200 includes a polishing pad 100, a disc-shaped base plate 210 that supports the polishing pad 100, a disc-shaped polishing head 220 that holds the workpiece W to be polished, a carrier 230 that holds the polishing head 220, a weight 240, and a supply nozzle 250 that supplies polishing fluid A. The base plate 210 is rotatable by a rotating shaft (not shown), and the polishing head 220 is rotatable by a rotating shaft 220A.

[0075] Then, in Figure 5, while supplying polishing liquid A containing water to the surface of the polishing pad 100, the polishing pad 100 and the workpiece W are slid relative to each other to polish the workpiece W.

[0076] Specifically, first, the polishing pad 100 is attached to the surface plate 210. Next, the workpiece W held by the polishing head 220 is pressed against the polishing surface of the polishing pad 100, and while supplying polishing fluid A from the supply nozzle 250, the surface plate 210 and / or the polishing head 220 are rotated. This causes the polishing pad 100 and the workpiece W to slide relative to each other, polishing the machined surface (polished surface) of the workpiece W.

[0077] The material of the workpiece W is not particularly limited and may be a ceramic material, a glass material, etc. Examples of ceramic materials include Si (silicon), SiC (silicon carbide), GaN (silicon nitride), GaAs (gallium arsenide), and sapphire, with SiC and GaN being preferred. Specifically, the workpiece W may be a material for semiconductor devices or electronic components, particularly Si substrates, SiC substrates, GaAs substrates, glass, or substrates for hard disks and LCDs (liquid crystal displays). Among these, semiconductor wafers are preferred, SiC substrates, sapphire substrates, or GaN substrates used in power devices are more preferred, and SiC substrates or GaN substrates are even more preferred.

[0078] 4. Modifications Although embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified as appropriate without departing from the technical spirit of the invention.

[0079] For example, in the above embodiment, an example was shown in which the polishing pad 100 has a first adhesive layer 130A and a second adhesive layer 130B, but these can be omitted. For example, when attaching the polishing pad 100 to the surface plate of the polishing machine, the second adhesive layer 130B may be omitted by applying or attaching adhesive to the surface plate side of the base layer 110. Also, when the polishing layer 120 is formed directly on the base layer 110, the first adhesive layer 130A may be omitted.

[0080] Furthermore, while the polishing pad 100 is generally disc-shaped with an outer diameter of 150 mm to 2000 mm, its shape may be appropriately modified to suit the polishing device. For example, the polishing pad 100 may have holes for passing a slurry tube through, in addition to the above-mentioned uneven shape. Alternatively, such holes may be formed in addition to, or instead of, the above-mentioned uneven shape to adjust the lifting force and make it easier to bend. The size of the holes can be, for example, 0.003R to 0.400R, where R is the outer diameter of the polishing pad.

[0081] The present disclosure will be described below with reference to examples. The scope of the present disclosure shall not be limited by the examples.

[0082] 1. Materials 1-1. Material of the polishing layer 1-1-1. Glycolic acid polymer PGA (hybricopolymer of glycolic acid, weight-average molecular weight 220,000, tensile modulus 10.3 GPa)

[0083] (Measurement of weight-average molecular weight) The weight-average molecular weight was measured by gel permeation chromatography (GPC). The measurement conditions were as follows: Apparatus: Showa Denko K.K. "Shodex-104" Column: Two HFIP-606M columns connected in series with one HFIP-G column as a pre-column Column temperature: 40°C Eluent: HFIP (hexafluoro-2-propanol) solution with 5 mM sodium trifluoroacetate dissolved in it Flow rate: 0.6 mL / min Detector: RI (differential refractive index) detector Molecular weight calibration: Five types of standard polymethyl methacrylate with different molecular weights

[0084] (Measurement of Tensile Modulus) The tensile modulus of the above PGA was measured in accordance with ISO 527.

[0085] 1-1-2. Abrasive single-crystal diamond powder FRM (manufactured by Global Diamond, median diameter 0.25 μm, amorphous)

[0086] (Method for measuring median diameter) The median diameter of the abrasive grains was measured using the following method. Specifically, a laser diffraction particle size analyzer Mastersizer 3000 (manufactured by Malvern) was used, with the following conditions set: measurement temperature 21°C, dispersion medium deionized water, dispersion medium refractive index 1.330, light scattering model Mie theory, particle absorptivity of polycrystalline diamond powder 0.100, and particle refractive index 2.418. The amount of abrasive grains added to the dispersion medium was adjusted so that the laser scattering intensity was between 4% and 10%.

[0087] 1-2. Materials other than the polishing layer 1-2-1. Base film Base 1: Polyethylene film (Polyethylene sheet PEN-101001 (purchased from AS ONE) whose surface has been ground and adjusted to a thickness of 0.5 mm) Base 2: Polyethylene film (Polyethylene sheet PEN-101001 (purchased from AS ONE) whose surface has been ground and adjusted to a thickness of 0.3 mm) Base 3: Polycarbonate film (Polycarbonate sheet KPAC1805-1 (purchased from AS ONE), thickness 0.5 mm) Base 4: Polycarbonate film (Polycarbonate sheet KPAC1805-1 (purchased from AS ONE) whose surface has been ground and adjusted to a thickness of 0.3 mm) Base 5: Polyethylene terephthalate film (Transparent PET sheet for Grip A (purchased from AS ONE) whose surface has been ground and adjusted to a thickness of 0.5 mm) Base material 6: Polyethylene terephthalate film (a transparent PET sheet for Grip A (purchased from AS ONE) whose surface has been ground down and adjusted to a thickness of 0.3 mm)

[0088] 1-2-2. Adhesives Adhesive A: DF8391S (Double-sided tape manufactured by Toyo Chem Co., Ltd., with a laminated structure of release paper / adhesive layer / base material / adhesive layer / release paper) Adhesive B: NT2600MX (Ripper manufactured by Nichiei Shinka Co., Ltd., double-sided tape with a laminated structure of release paper / adhesive layer / base material / adhesive layer / release paper)

[0089] 2. Preparation of Laminate (Polishing Pad) 2-1. Preparation of Laminate 1 (1) Preparation of Polishing Layer (Mixing Process) Each component shown in Table 1 was weighed in the proportions shown in Table 1, and the composition was obtained by mixing using a Laboplast Mill (manufactured by Toyo Seiki Seisakusho). Mixing was performed at a predetermined heater temperature with a preheating time of 1 minute, a mixing time of 5 minutes, and a rotation speed of 50 rpm. The heater temperature was set to 250°C.

[0090] (Molding Process) A stainless steel mold with a 150 mm diameter hole was prepared. The mixed composition was placed in this stainless steel mold and press-molded to produce a disc-shaped molded body with a thickness of 2.0 mm. The press machine temperature was set to the same temperature as the heater temperature of the Laboplast Mill.

[0091] (Roughness formation process) Grooves were formed in a grid pattern on the surface of the obtained molded body using a CNC router machine, as shown in Figure 3A. Groove depth (height of protrusions t) ２２ ) is 1.5 mm, groove bottom thickness (thickness of recessed part t ２２ The height of the protrusions (t) was 0.5 mm, the groove width (minimum spacing between protrusions w) was 1 mm, and the groove spacing (p pitch of protrusions) was 5 mm. S2 / S1 was 0.56. ２２ The minimum spacing (w), pitch (p), and S2 / S1 were measured using the method described above with a Keyence VR-5000 one-shot 3D shape measuring machine.

[0092] (2) Adhesive A was applied to one side and the other side of the laminated substrate film 1 using a laminator to form an adhesive layer. The lamination conditions were room temperature (23°C), speed 0.7 m / min, and pressure 0.2 MPa.

[0093] The polished layer prepared above was bonded to the adhesive layer on one side of the base film 1 of the resulting laminate using a laminator. The lamination conditions were the same as described above. Subsequently, the area around the portion other than the polished layer was cut along the shape of the polished layer to obtain a laminate 1 in which the adhesive layer (second adhesive layer), base film, adhesive layer (first adhesive layer), and polished layer were laminated in this order.

[0094] 2-2. Preparation of Laminates 2, 14, 16, and 19 Laminates 2, 14, 16, and 19 were prepared in the same manner as laminate 1, except that the spacing of the grooves formed on the surface of the polished layer (pitch of the protrusions) and at least one of S2 / S1 were changed as shown in Table 1.

[0095] 2-3. Fabrication of Laminate 3: Thickness of polished layer and depth of groove (height of protrusion t) ２２ Laminate 3 was manufactured in the same manner as laminate 1, except that the following was changed as shown in Table 1.

[0096] 2-4. Fabrication of Laminate 4 Laminate 4 was fabricated in the same manner as laminate 1, except that the size of the polished layer was changed as shown in Table 1.

[0097] 2-5. Preparation of Laminates 5, 6, 20, 21, and 22 Laminates 5, 6, 20, 21, and 22 were prepared in the same manner as laminate 1, except that the type and thickness of the base film were changed as shown in Table 1.

[0098] 2-6. Preparation of Laminate 7 Laminate 7 was prepared in the same manner as laminate 1, except that the type of adhesive was changed as shown in Table 1. Specifically, two pieces of double-sided tape, adhesive B, were prepared and attached to one side and the other side of the base film shown in Table 1.

[0099] Then, the release paper of the double-sided tape attached to the base film was peeled off, and the polished layer was attached to the exposed adhesive layer, except that the laminate 7 was prepared in the same manner as laminate 1.

[0100] 2-7. Fabrication of Laminate 8 Laminate 8 was fabricated in the same manner as laminate 1, except that the thickness of the polished layer was changed as shown in Table 1 and grooves were not formed on the surface of the polished layer.

[0101] 2-8. Fabrication of Laminate 9 Laminate 9 was fabricated in the same manner as laminate 1, except that grooves were not formed on the surface of the polished layer.

[0102] 2-9. Preparation of Laminates 10 and 11 Laminates 10 and 11 were prepared in the same manner as laminate 1, except that the depth of the grooves formed in the polished layer was changed as shown in Table 1.

[0103] 2-10. Preparation of Laminate 12 Laminate 12 was prepared in the same manner as laminate 1, except that the abrasive content was changed as shown in Table 1.

[0104] 2-11. Preparation of Laminate 13 Laminate 13 was prepared in the same manner as laminate 1, except that the average particle size of the abrasive grains was changed as shown in Table 1.

[0105] 2-12. Fabrication of Laminate 15 Laminate 15 was fabricated in the same manner as laminate 1, except that the thickness of the polished layer and the depth of the grooves formed in the polished layer were changed as shown in Table 1.

[0106] 2-13. Preparation of Laminate 17 Laminate 17 was prepared in the same manner as laminate 1, except that the depth of the grooves formed in the polished layer, the spacing of the grooves (pitch p of the protrusions), S2 / S1, and the type of base film were changed as shown in Table 1.

[0107] 2-14. Preparation of Laminate 18 Laminate 18 was prepared in the same manner as laminate 1, except that the spacing of the grooves formed on the surface of the polished layer (pitch of the protrusions), S2 / S1, and the type of base film were changed as shown in Table 1.

[0108] 3. Evaluation of the Laminate 3-1. Flexural Modulus E The laminate was cut into 105 x 15 mm pieces to serve as test specimens. Bending tests were performed on these specimens using an A&D Company, Limited Tensilon universal material testing machine RTF-2350, in accordance with JIS K7074:1988, with a support distance of 80 mm and a crosshead speed of 5 mm / min. The flexural modulus was calculated from the obtained displacement and load. Measurements were performed with n=3, and the average value was taken as the flexural modulus.

[0109] 3-2. The thickness of the laminated material per unit length was measured using a Mitutoyo PMU300-25MB U-shaped steel plate micrometer. The center of the laminate was defined as O, and the distance from the center O to the end of the laminate was defined as 1. A circle with a radius of 0.6 was drawn from the center O, and the circumference of this circle was divided into 10 equal parts. Ten points on each of these points were used as measurement points. The average value of these 10 points was calculated and defined as the thickness of the laminate. The bending stiffness per unit length (Fr) was then calculated by applying the thickness of the laminate (h) and the measured bending modulus (E) to the following formula: Fr = E × h ３ / 12...Equation (1) In Equation (1), E represents the flexural modulus of the laminate and h represents the thickness of the laminate.

[0110] 3-3. Lifting Force A φ5 mm hole was drilled 25 mm from the other end of the laminate on its centerline. The other end of the laminate, opposite to the aforementioned end, was bonded to the base 2 via the second adhesive layer. The length of the bonded portion 3 on L1 was 3 / 4 of the diameter of the laminate (see Figure 4A). A spring scale was then hooked into the hole formed in the laminate and pulled up (see Figure 4B). The lifting force was measured from the reading on the spring scale when it was lifted 30 mm.

[0111] 3-4. Sensory Evaluation The ease of bending the laminate when attaching it to the surface plate was evaluated according to the following criteria: A: Can be bent well without cracking B: Requires some force but can be bent generally well with almost no cracking C: Difficult to bend, and cracking occurs if bent forcibly

[0112] 3-5. Evaluation Results The manufacturing conditions for laminates 1 to 22 are shown in Table 1, and the evaluation results are shown in Table 2.

[0113]

[0114]

[0115] As shown in Tables 1 and 2, the bending stiffness per unit length is 1.9 Pa·m ３ Laminates 1-8, 11-16, and 20-22, as described below, have a bending stiffness of 1.9 Pa·m per unit length. ３ It can be seen that these laminates are easier to bend and less prone to cracking when attached to a surface plate than laminates 9, 10, and 17-19, which have higher density.

[0116] This application claims priority under Japanese Patent Application No. 2025-52212, filed on 26 March 2025. All contents described in the specification and drawings of said application are incorporated herein by reference.

[0117] According to the present invention, it is possible to provide a polishing pad that is easy to bend and less prone to cracking, for example, when attaching it to a surface plate.

[0118] 1 Hole 2 Base 3 Adhesive part 4 Spring balance 100 Polishing pad 110 Base layer 120 Polishing layer 121 Protrusion 122 Recess 130A First adhesive layer 130B Second adhesive layer 200 Polishing device 210 Surface plate 220 Polishing head 220A Rotating shaft 230 Carrier 240 Weight 250 Supply nozzle W Workpiece A Polishing liquid O Center L1 Center line L2 End of adhesive part w Minimum distance between adjacent protrusions 121 p Distance between the centers of protrusions 121 t ２１ Thickness t of recessed portion 122 ２２ Height of the protrusion 121 T1 Thickness of the base layer T2 Thickness of the polished layer

Claims

1. The material comprises a base layer and an abrasive layer disposed on the base layer, the abrasive layer containing a glycolic acid polymer and abrasive particles, and the bending stiffness Fr per unit length, expressed by formula (1) at 25°C and 30% RH, is 1.9 Pa·m ３ The following is the polishing pad: Fr = E × h ３ / 12....Equation (1) (In Equation (1), E represents the flexural modulus of the polishing pad (MPa), and h represents the thickness of the polishing pad (mm)) 2. The polishing pad according to claim 1, wherein when one end of the polishing pad is bonded to the base via an adhesive, the lifting force required to maintain the other end of the polishing pad at a height of 30 mm above the base is 50.0 N or less.

3. The polishing pad according to claim 1 or 2, wherein the content of abrasive grains in the polishing layer is 1% by mass or more and 55% by mass or less with respect to the total mass of the polishing layer.

4. The polishing pad according to any one of claims 1 to 3, wherein the thickness of the polishing layer is 1.0 mm or more and 50 mm or less.

5. The polishing pad according to any one of claims 1 to 4, wherein the polishing layer has an uneven shape with a plurality of protrusions.

6. The polishing pad according to claim 5, wherein, in the polishing layer, when S1 is the sum of the horizontal projected areas of the plurality of protrusions and S2 is the sum of the horizontal projected areas of the recessed portions excluding the plurality of protrusions, S2 / S1 is 1.3 or less.

7. The polishing pad according to claim 5 or 6, wherein the thickness of the polishing layer in the recessed portion formed around the convex portion is 60% or less of the thickness of the polishing layer.

8. The polishing pad according to any one of claims 5 to 7, wherein the tensile modulus of the base material layer is lower than the tensile modulus of the glycolic acid polymer, and when the thickness of the base material layer is T1 and the thickness of the polishing layer is T2, T1 / T2 is 0.02 or more and 1.0 or less.

9. The polishing pad according to any one of claims 1 to 8, wherein the base layer comprises a polyolefin film, a polyester film, or a polycarbonate film.

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