Polishing pad and wafer polishing method

Abstract

To provide a polishing pad that in polishing an outer peripheral edge part of a wafer in a disc shape, polishes the part with higher efficiency and hardly causes a polishing failure, and is excellent in performance in washing the polished wafer.SOLUTION: A polishing pad 1 according to the present invention polishes an outer peripheral edge part of a wafer 3 in a disc shape. A polishing surface of the polishing pad 1 is constituted of a polishing body, where the polishing body includes a base material and polishing particles. The base material is made of binder resin and fiber and has a plurality of gas pockets formed therein. The polishing particles are held in the base material or in the gas pockets. The polishing particles are diamonds, whose densities are 0.58-0.81 g / cm3 and whose durometer hardness is 16-27 and whose elastic modulus is 21.5-37.5 N / mm2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a polishing pad and a method for polishing a wafer. [Background technology]

[0002] Patent Documents 1 to 4 disclose conventional polishing pads. The polishing pads in Patent Documents 1 to 3 are made by impregnating a nonwoven fabric with a paste and then removing the solvent from the paste. The paste in Patent Document 1 consists of urethane, a solvent such as dimethylformamide, abrasive particles such as SiO2, and alkaline fine particles such as sodium carbonate. The paste in Patent Document 2 consists of an ether-based urethane and a solvent such as N,N-dimethylformamide. The paste in Patent Document 3 consists of urethane, a solvent, and a water repellent. By removing the solvent by drying or the like, the urethane is solidified while bonded to the nonwoven fabric. The polishing pad in Patent Document 4 is made using a paste made by mixing a binder resin, abrasive particles, and a solvent.

[0003] The polishing pad of Patent Document 1 is used to polish the outer peripheral edge of a disk-shaped wafer made of silicon or the like used in manufacturing semiconductor devices. Specifically, the wafer is held on a rotating table that can rotate around its center of rotation. The central axis of the wafer is positioned at the center of rotation of the rotating table. Meanwhile, a polishing pad is mounted on the upper end of a spindle so that the outer peripheral edge of the polishing pad abuts against the outer peripheral edge of the wafer. A polishing liquid is then supplied between the outer peripheral edge of the wafer and the outer peripheral edge of the polishing pad, and the rotating table and spindle are rotated while a predetermined load is applied. This allows the outer peripheral edge of the wafer to be polished. This makes it possible to suppress the occurrence of defects in semiconductor devices due to the outer peripheral edge of the wafer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-46838 [Patent Document 2] Japanese Patent Application Publication No. 2019-118981 [Patent Document 3] Japanese Patent Application Publication No. 2020-49639 [Patent Document 4] Patent No. 5511266 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the inventors' tests, when polishing the peripheral edge of a disc-shaped wafer, conventional polishing pads have insufficient polishing efficiency, low flexibility and low recovery rate after compression, and poor conformability when pressed against the wafer. As a result, polishing takes a long time and there is a risk of polishing failure. Furthermore, since the polishing pad does not contain abrasive grains, when a polishing liquid containing abrasive grains is used for free abrasive polishing, it is necessary to clean the particles, which are abrasive particles remaining on the wafer after polishing, which causes problems with cleanability.

[0006] In particular, when the wafers are made of SiC, which can be used to manufacture power semiconductors, a higher polishing capacity is required.

[0007] The present invention has been made in consideration of the above-mentioned conventional situation, and aims to provide a polishing pad that, when polishing the outer peripheral edge of a disc-shaped wafer, has higher polishing efficiency, is less likely to cause polishing defects, and has excellent post-polishing wafer cleanability. The present invention also aims to provide a wafer polishing method that can polish the outer peripheral edge of a disc-shaped wafer with higher efficiency, is less likely to cause polishing defects, and has excellent post-polishing wafer cleanability. [Means for solving the problem]

[0008] The polishing pad of the present invention is a polishing pad for polishing the outer peripheral edge of a disk-shaped wafer, a polishing body that includes a base material made of a binder resin and fibers and having a plurality of pores formed therein, and abrasive particles held in the base material or the pores, and that forms a polishing surface; the abrasive particles are diamond; the wafer is made of SiC; the abrasive body includes a filler held within the matrix or within the pores; the fibers are configured by a fiber web, and the binder resin, the abrasive particles, the pores, and the filler are contained within the fiber web; the binder resin is thermoplastic polyurethane or polyvinylidene fluoride, the fibers are polypropylene; the filler is silica; Durometer hardness is 16 to 27, Density: 0.58~0.81g / cm 3 and Elastic modulus: 21.5 to 37.5 N / mm 2 It is characterized in that:

[0009] The wafer polishing method of the present invention includes a first step of preparing a wafer, a polishing pad, and a polishing liquid; a second step of polishing the wafer with the polishing pad while supplying the polishing liquid between the wafer and the polishing pad; the wafer has a central axis, a front surface extending in a direction substantially perpendicular to the central axis, a back surface located opposite to the front surface and extending in a direction substantially perpendicular to the central axis, an outer circumferential surface connecting an outer circumferential edge of the front surface with an outer circumferential edge of the back surface, and an outer circumferential edge portion formed by the front surface or the back surface and the outer circumferential surface, the polishing pad has a polishing body that comprises a base material made of a binder resin and fibers and having a plurality of pores formed therein, and abrasive particles held in the base material or the pores, and that forms a polishing surface; The polishing pad has abrasive particles that are diamonds, the wafer is made of SiC; the abrasive body includes a filler held within the matrix or within the pores; the fibers are configured by a fiber web, and the binder resin, the abrasive particles, the pores, and the filler are contained within the fiber web; the binder resin is thermoplastic polyurethane or polyvinylidene fluoride, the fibers are polypropylene; the filler is silica; Durometer hardness is 16 to 27, Density: 0.58~0.81g / cm 3 and Elastic modulus: 21.5 to 37.5 N / mm 2 and In the second step, the polishing surface is pressed against the outer peripheral edge portion with a predetermined pressing force while the polishing liquid is water, and at least one of the wafer and the polishing pad is rotated relative to one another around the central axis.

[0010] The polishing pad of the present invention has diamond abrasive particles, and therefore can achieve excellent polishing efficiency.

[0011] Furthermore, according to the inventors' tests, when the peripheral edge of a disc-shaped wafer is polished with the polishing pad of the present invention, the diamond abrasive particles have excellent trackability when polishing the wafer, and polishing defects are unlikely to occur. Furthermore, since the polishing body constituting the polishing surface of the polishing pad of the present invention contains countless abrasive particles, a polishing liquid that does not contain abrasive grains can be used, and since there are few particles, which are abrasive particles, remaining on the wafer after polishing, the wafer is easy to clean after polishing. [Effects of the Invention]

[0012] According to the present invention, when polishing the outer peripheral edge of a disk-shaped wafer, the polishing efficiency is higher, polishing defects are less likely to occur, and the wafer is easier to clean after polishing. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of the polishing pads of test samples 1 to 20. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the method for polishing wafers in Examples 1 to 20 and Comparative Examples 1 to 4. [Figure 3] FIG. 3 is a SEM photograph of the polishing pad of Test Sample 3 at 300x magnification. [Figure 4] FIG. 4 is a SEM photograph of the polishing pad of Test Sample 3 at 3000x magnification. [Figure 5]FIG. 5 is a 300x SEM photograph of the polishing pad of Test Sample 7. [Figure 6] FIG. 6 is an SEM photograph of the polishing pad of Test Sample 7 at 3000x magnification. [Figure 7] FIG. 7 is a 300x SEM photograph of the polishing pad of specimen 11. [Figure 8] FIG. 8 is an SEM photograph of the polishing pad of specimen 11 at 3000x magnification. [Figure 9] FIG. 9 is a 300x SEM photograph of the polishing pad of specimen 15. [Figure 10] FIG. 10 is an SEM photograph of the polishing pad of specimen 15 at 3000x magnification. DETAILED DESCRIPTION OF THE INVENTION

[0014] The polishing pad of the present invention has a polishing surface formed by an abrasive body, which contains a matrix and abrasive particles. The matrix is ​​made of a binder resin and fibers and has a plurality of pores formed therein. The abrasive particles are held within the matrix or the pores.

[0015] The binder resin is thermoplastic polyurethane (TPU). or Polyvinylidene fluoride (PVDF) )of It is possible to adopt 。

[0016] The abrasive particles are diamond. The abrasive body preferably contains a filler held within the matrix or pores. The filler may be an inorganic powder, inorganic fiber, resin powder, resin fiber, metal powder, or metal fiber, which are softer than diamond. It is believed that the filler prevents the abrasive particles from agglomerating, elastically holds the abrasive particles, and alleviates the reaction force acting on the abrasive particles during abrasion. Furthermore, depending on the filler material, wear resistance can be improved.

[0017] Inorganic powders used as fillers include 、 Siri Ka Can be mentioned 。

[0018] Fiber is , polyps Polypropylene (PP) fiber Maintain These can be adopted. Fiber It is also possible to select the shape, such as fiber length and thickness.

[0019] The fibers of the polishing pad may be based on a preformed or non-preformed fiber web. A fiber web is a layer of fibers arranged in a longitudinal, crossed, or random fiber orientation. A nonwoven fabric is a fiber web in which the fibers are bonded together.

[0020] The polishing pad of the present invention can be manufactured by the following manufacturing method: This manufacturing method includes a preparation step of preparing a paste containing a binder resin, a solvent for dissolving the binder resin, and numerous abrasive particles, and a fiber web; an impregnation step of impregnating the fiber web with the paste to form an impregnated body; and a solidification step of removing the solvent from the impregnated body to solidify the binder resin.

[0021] The abrasive body of the polishing pad obtained by this manufacturing method includes a fiber web that constitutes the fibers, and a binder resin and abrasive particles contained within the fiber web. In this case, since the fibers are pre-formed into the fiber web, the productivity of the polishing pad is high.

[0022] The paste contains a binder resin, numerous abrasive particles, and a solvent. Examples of solvents that can be used include N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethyl sulfoxide, acetone, ethyl acetate, and methyl ethyl ketone. These may be used alone or in combination of two or more. The solvent is selected from a variety of solvents depending on the binder resin.

[0023] The paste may also contain alkaline fine particles such as sodium carbonate, piperazine, potassium hydroxide, sodium hydroxide, calcium oxide, potassium carbonate, and magnesium oxide. The paste may also contain a water repellent such as a fluorine-based water repellent, a silicon-based water repellent, a hydrocarbon-based water repellent, or a metal compound-based water repellent. Furthermore, the paste may also contain a pigment such as an inorganic pigment such as titanium dioxide, calcium carbonate, or carbon black, or an organic pigment such as an azo pigment or a polycyclic pigment. These may be used alone or in combination of two or more.

[0024] When a polishing liquid is used, the polishing liquid may be pure water, an oil-based liquid, or a liquid containing an acidic or alkaline chemical.

[0025] According to the results of the inventors' tests, it is preferable that the binder resin is thermoplastic polyurethane or polyvinylidene fluoride and the fibers are polypropylene, which provides excellent conformability when pressed against the wafer.

[0026] Furthermore, according to the inventors' test results, it is preferable that the binder resin is 9.5 to 34.6 volume %, the abrasive particles are 2.2 to 14.3 volume %, the fibers are 5.1 to 10.2 volume %, the filler is 0 to 17.6 volume %, and the pores are 34.6 to 68.5 volume %, which results in excellent wear resistance and excellent polishing efficiency.

[0027] (test)

[0028] As shown in Table 1, the combinations of the fiber web, binder resin, and particle size of the abrasive particles were changed, and polishing pads 1 of test samples 11 to 20 were manufactured by the manufacturing method described below.

[0029] [Table 1]

[0030] First, as a preparation step, the following binder resin, solvent, abrasive particles, and fiber web were prepared. The fiber web was formed in a disk shape centered on the first rotation axis P, similar to the polishing pad 1 to be manufactured as shown in FIG.

[0031] (binder resin) PVDF (Polyvinylidene Fluoride) TPU (thermoplastic polyurethane) (solvent) NMP (N-methyl-2-pyrrolidone) (abrasive particles) Diamond (average particle size: 1 μm, 5 μm, 10 μm, 20 μm) (fiber web) 100% PP (polypropylene) fiber, basis weight 200g / m 2 100% PP (polypropylene) fiber, basis weight 400g / m 2 (filler) Silica (SiO2) (average particle size: 200 nm)

[0032] As shown in Table 1, the combination of fiber web, binder resin, abrasive particle diameter, and paste was changed, and the binder resin, abrasive particles, filler, and solvent were mixed in the parts by mass shown in Table 1 to form a paste.

[0033] In this case, the number of abrasive particles in the polishing pad 1 was the same even if the particle size of the abrasive grains was different. If the binder resin was powdered PVDF, the abrasive particles and binder resin were dry mixed, and the mixture was dissolved in a slurry containing a solvent and filler, and the abrasive particles were dispersed in the paste. On the other hand, if the binder resin was bead-like TPU, the binder resin was first dissolved in a slurry together with a solvent and filler, and the abrasive particles were added to the slurry, and the abrasive particles were dispersed in the paste using a planetary mixer.

[0034] Then, in the impregnation process, each paste was brought into contact with the front and back surfaces of each fiber web while applying a load, and each fiber web was impregnated with each paste to form an impregnated body. Next, in the solidification process, each obtained impregnated body was dried to remove the solvent from each impregnated body and solidify the binder resin. In this way, each polishing body was obtained. The outer and inner peripheral portions of each polishing body were cut away around the first rotation axis P to obtain polishing pads 1 for test samples 1 to 20.

[0035] As shown in FIG. 1, each polishing pad 1 is formed in a disk shape centered on the first rotation axis P. FIG. 3 shows an SEM photograph of the polishing pad of test sample 3 at 300x magnification, and FIG. 4 shows an SEM photograph of the polishing pad of test sample 3 at 3000x magnification. FIG. 5 shows an SEM photograph of the polishing pad of test sample 7 at 300x magnification, and FIG. 6 shows an SEM photograph of the polishing pad of test sample 7 at 3000x magnification. FIG. 7 shows an SEM photograph of the polishing pad of test sample 11 at 300x magnification, and FIG. 8 shows an SEM photograph of the polishing pad of test sample 11 at 3000x magnification. FIG. 9 shows an SEM photograph of the polishing pad of test sample 15 at 300x magnification, and FIG. 10 shows an SEM photograph of the polishing pad of test sample 15 at 3000x magnification.

[0036] As shown in Figures 3 to 10, each polishing pad 1 is made up of a polishing body that forms the front and back polishing surfaces. Each polishing body includes a base material and abrasive particles. Each base material is made up of a binder resin and fibers, and has a plurality of pores formed therein. The abrasive particles are held within the base material or within the pores. The polishing body includes a fiber web that forms the fibers, and a binder resin and abrasive particles contained within the fiber web. Because the fibers are pre-formed as a fiber web, the productivity of the polishing pad 1 is high.

[0037] The volume percentages of binder resin, abrasive particles, fibers, filler, and pores in the polishing pads 1 of test samples 1 to 20 are as shown in Table 2. More specifically, the base material of the polishing pads 1 of test samples 1 to 16 has a filler, while the base material of the polishing pads 1 of test samples 17 to 20 does not have a filler.

[0038] [Table 2]

[0039] Also, the density (g / cm 3 ) of the polishing surface of the polishing pads 1 of test pieces 1 to 20 thus obtained, the durometer hardness, and the elastic modulus (N / mm 2 ) are shown in Table 3.

[0040]

Table 3

[0041] A polishing apparatus shown in FIG. 2 and a wafer 3 (6-inch diameter) before polishing made of SiC were prepared. The polishing apparatus is "FINE SURFACE E-200" manufactured by BBS Kimei, and includes a drum (not shown) capable of rotating the wafer 3 around the rotation center Q and a chuck 5.

[0042] The wafer 3 has a central axis Q, a surface 3a extending in a direction substantially orthogonal to the central axis Q, a back surface 3b located opposite to the surface 3a and extending in a direction substantially orthogonal to the central axis Q, an outer peripheral surface 3c connecting the outer peripheral edge of the surface 3a and the outer peripheral edge of the back surface 3b, a surface-side outer peripheral edge portion 3d formed by the surface 3a and the outer peripheral surface 3c, and a back surface-side outer peripheral edge portion 3e formed by the back surface 3b and the outer peripheral surface 3c.

[0043] The chuck 5 of the polishing apparatus can hold the polishing pads 1 of test pieces 1 to 20 and rotate at a predetermined rotational speed, and the polishing surface of the polishing pad 1 can be displaced at an angle θ with respect to the outer peripheral surface 3c, the surface 3d, and the back surface 3e of the wafer 3 and can be pressed with a predetermined load.

[0044] The conditions for the TOP part for polishing the outer peripheral surface 3c with θ = 90°, the conditions for the ACF part for polishing the surface-side outer peripheral edge portion 3d with θ = 21°, and the conditions for the BCF part for polishing the back surface-side outer peripheral edge portion 3e with θ = 111° are as follows. <TOP part> Rotational speed of the drum: 200 rpm (pressed by centrifugal force) Vertical speed: 1.5 mm / second Rotational speed of the chuck 5: 10 rpm

[0045] <ACF part and BCF part> Rotation speed of drum: 300 rpm (pressed by centrifugal force) Load: 5 kgf Rotation speed of chuck 5: 10 rpm

[0046] As shown in Table 4, in Examples 1 to 20, any one of Test Specimens 1 to 20 was used to perform the first processing or the first to third processings. At this time, pure water was used as the polishing liquid. Note that the processing time of A / BCF indicates the time for processing both the ACF part and the BCF part respectively.

[0047]

Table 4

[0048] On the other hand, in Comparative Example 1, the first processing was performed using a non-woven pad (100% polyester fiber, fiber diameter 14 μm, 3.0 mm thick) as the polishing pad 1. At this time, a commercially available colloidal silica slurry (containing SiO2 with an average particle size of 50 nm at 10000 ppm or less) was used as the polishing liquid. The processing time was 180 minutes.

[0049] In Comparative Example 2, the first processing was performed using an LHA pad (manufactured by the manufacturing method described in Japanese Patent No. 5511266 using a paste obtained by mixing 11% by mass of a binder resin (PVDF), 34% by mass of polishing particles, and 56% by mass of a solvent) as the polishing pad 1. At this time, a commercially available lubricant (KMnO4: 0.25 mol) was used as the polishing liquid. The processing time was 115 minutes.

[0050] In Comparative Example 3, the first processing was performed using a silica-containing polishing pad (a fiber web made of PP with a basis weight of 200 g / m 2 containing 12% by volume of SiO2 with an average particle size of 0.2 μm) as the polishing pad 1. At this time, a commercially available lubricant (KMnO4: 0.25 mol) was used as the polishing liquid. The processing time was 180 minutes.

[0051] In Comparative Example 4, a silica-containing polishing pad (made of PP with a basis weight of 400 g / m 2 The first processing was carried out using a fiber web containing 11% by volume of SiO2 with an average particle size of 0.2 μm as polishing pad 1. In this case, a commercially available lubricant (KMnO4: 0.25 mol) was used as the polishing liquid. The processing time was 180 minutes.

[0052] The polishing time, the presence or absence of unpolished areas, the surface roughness of the polished wafer 3, particles, and the polishing liquid were evaluated. In this case, the surface roughness of the polished wafer 3 was evaluated on the outer peripheral surface 3c (TOP), the front outer peripheral edge 3d (ACF), and the back outer peripheral edge 3e (BCF).

[0053] Regarding the polishing time and whether or not there were any areas left unpolished, if the polishing time was within 50 minutes and there were no areas left unpolished, it was marked as ◎; if the polishing time was more than 50 minutes but less than 100 minutes and there were no areas left unpolished, it was marked as ○; if the polishing time was more than 100 minutes but less than 150 minutes and there were no areas left unpolished, it was marked as △; if the polishing time was more than 150 minutes and there were areas left unpolished, it was marked as ×.

[0054] Regarding the surface roughness of the wafer after polishing, if Sa was less than 10 nm, it was marked as ◎; if Sa was 10 nm or more but less than 20 nm, it was marked as ◯; if Sa was 20 nm or more but less than 50 nm, it was marked as △; and if Sa was 50 nm or more, it was marked as ×.

[0055] Regarding particles, the number of particles was judged by observation under an electron microscope as follows: 0 particles within a 5 μm x 5 μm area was judged as ◎; more than 0 but less than 5 particles was judged as 〇; 5 or more but less than 10 particles was judged as △; and 10 or more particles was judged as ×.

[0056] Regarding the polishing liquid, if polishing was possible with an abrasive particle concentration of 0 ppm, it was marked with an ◎; if polishing was not possible unless the abrasive particle concentration was 1 ppm or more and less than 1000 ppm, it was marked with an 〇; if polishing was not possible unless the abrasive particle concentration was 1000 ppm or more and less than 5000 ppm, it was marked with a △; and if polishing was not possible unless the abrasive particle concentration was 5000 ppm or more and 10000 ppm or less, it was marked with an ×.

[0057] Overall, if the polishing time, the presence or absence of unpolished areas, the surface roughness of the wafer after polishing, the particles, and the polishing liquid were all △ or higher, it was marked as ◯, and if all of these were ○ or higher, it was marked as ◎. The results are shown in Tables 5 and 6.

[0058] [Table 5]

[0059] [Table 6]

[0060] From Tables 5 and 6, it can be seen that the polishing pads 1 of test samples 1 to 20 have excellent polishing efficiency because the abrasive particles are diamond. In addition, the polishing pads 1 of test samples 1 to 20 have a density of 0.58 to 0.81 g / cm 3 The durometer hardness is 16 to 27, and the elastic modulus is 21.5 to 37.5 N / mm 2 Therefore, when the wafer 3 is polished with diamond abrasive particles, the pads have excellent tracking properties and are less likely to produce polishing defects. Furthermore, the polishing pads 1 of test samples 1 to 20 have a polishing body that comprises countless abrasive particles, so simple water that does not contain abrasive grains can be used, and since few particles (abrasive particles) remain on the wafer 3 after polishing, the pads have excellent cleaning properties for the polished wafer.

[0061] Therefore, according to the polishing methods of Examples 1 to 20 using the polishing pads 1 of test specimens 1 to 20, when polishing the outer edge of a disc-shaped wafer 3, the polishing efficiency is higher, polishing defects are less likely to occur, and the wafer is easier to clean after polishing.

[0062] On the other hand, the polishing methods of Comparative Examples 1 to 4 using conventional polishing pad 1 leave a lot of unpolished areas and are poor in polishing efficiency. In particular, the polishing method of Comparative Example 1 is poor in the cleanability of the wafer after polishing.

[0063] The present invention has been described above in accordance with Examples 1 to 20, but it goes without saying that the present invention is not limited to the above Examples 1 to 20, and can be modified and applied as appropriate within the scope of the invention.

[0064] For example, in Examples 1 to 20, wafer 3 made of SiC was polished, but the polishing pad and wafer polishing method of the present invention can also be applied to polishing wafers made of Si. [Industrial Applicability]

[0065] The present invention can be used in semiconductor device manufacturing equipment. [Explanation of symbols]

[0066] 3...Wafer 1...Polishing pad Q…Central axis line 3a…Surface 3b…Back side

Claims

1. A polishing pad for polishing the outer peripheral edge of a disk-shaped wafer, a polishing body that includes a base material made of a binder resin and fibers and having a plurality of pores formed therein, and abrasive particles held in the base material or the pores, and that forms a polishing surface; the abrasive particles are diamond; the wafer is made of SiC; the abrasive body includes a filler held within the matrix or within the pores; the fibers are configured by a fiber web, and the binder resin, the abrasive particles, the pores, and the filler are contained within the fiber web; the binder resin is thermoplastic polyurethane or polyvinylidene fluoride, the fibers are polypropylene; the filler is silica; Durometer hardness is 16 to 27, Density 0.58 to 0.81 g / cm 3 and Elastic modulus: 21.5 to 37.5 N / mm 2 A polishing pad characterized by:

2. Durometer hardness is 16 to 23, Density is 0.58 to 0.73 g / cm 3 and Elastic modulus: 22.6 to 37.0 N / mm 2 2. The polishing pad according to claim 1, wherein

3. A first step of preparing a wafer, a polishing pad, and a polishing liquid; a second step of polishing the wafer with the polishing pad while supplying the polishing liquid between the wafer and the polishing pad; the wafer has a central axis, a front surface extending in a direction substantially perpendicular to the central axis, a back surface located opposite to the front surface and extending in a direction substantially perpendicular to the central axis, an outer circumferential surface connecting an outer circumferential edge of the front surface with an outer circumferential edge of the back surface, and an outer circumferential edge portion formed by the front surface or the back surface and the outer circumferential surface, the polishing pad has a polishing body that comprises a base material made of a binder resin and fibers and having a plurality of pores formed therein, and abrasive particles held in the base material or the pores, and that forms a polishing surface; The polishing pad has abrasive particles that are diamonds, the wafer is made of SiC; the abrasive body includes a filler held within the matrix or within the pores; the fibers are configured by a fiber web, and the binder resin, the abrasive particles, the pores, and the filler are contained within the fiber web; the binder resin is thermoplastic polyurethane or polyvinylidene fluoride, the fibers are polypropylene; the filler is silica; Durometer hardness is 16 to 27, Density 0.58 to 0.81 g / cm 3 and Elastic modulus: 21.5 to 37.5 N / mm 2 and In the second step, the polishing surface is pressed against the outer peripheral edge portion with a predetermined pressing force while the polishing liquid is water, and at least one of the wafer and the polishing pad is rotated relative to one another around the central axis.

4. Durometer hardness is 16 to 23, Density is 0.58 to 0.73 g / cm 3 and Elastic modulus: 22.6 to 37.0 N / mm 2 4. The wafer polishing method according to claim 3, wherein

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