Polishing pad and wafer notch polishing method

Abstract

A polishing pad ( 1 ) of the present teaching is formed in an annular shape and is centered on a first rotation axis center (P). The polishing pad ( 1 ) has a first surface ( 1 a ), a second surface ( 1 b ), and a polishing surface ( 3 ) that connects the first surface ( 1 a ) and the second surface ( 1 b ) on an outer circumference of the polishing pad ( 1 ). The polishing pad ( 1 ) polishes a notch ( 7 ), which is formed in a disc-shaped wafer ( 5 ) and indicates an orientation of a crystal axis, by rotating around the first rotation axis center (P) while pressing the polishing surface ( 3 ) against the notch ( 7 ). The polishing surface ( 3 ) is formed of a polishing body that includes: a base material composed of a binder resin and fibers and having a plurality of pores formed therein; and polishing particles retained in the base material or in the pores.

1 . A polishing pad that is formed in an annular shape and is centered on a first rotation axis center,
 the polishing pad having: an annular first surface that extends in a direction substantially orthogonal to the first rotation axis center; an annular second surface that extends in the direction substantially orthogonal to the first rotation axis center and is positioned opposite to the first surface; and a polishing surface that connects the first surface and the second surface on an outer circumference of the polishing pad,   the polishing pad that polishes a notch, which is formed in a disc-shaped wafer and indicates an orientation of a crystal axis, by rotating around the first rotation axis center while pressing the polishing surface against the notch,   wherein the polishing surface is formed of a polishing body that includes: a base material composed of a binder resin and fibers and having a plurality of pores formed therein; and polishing particles retained in the base material or in the pores.   
     
     
         2 . The polishing pad according to  claim 1 ,
 wherein the polishing surface has: a third surface that is continuous with the first surface and forms a tapered shape such that a distance between the first rotation axis center and the third surface becomes larger as the third surface approaches the second surface; and a fourth surface that is continuous with the second surface and forms a tapered shape such that a distance between the first rotation axis center and the fourth surface becomes larger as the fourth surface approaches the first surface, and   the third surface and the fourth surface have an interior angle that is consistent with an opening angle of the notch.   
     
     
         3 . The polishing pad according to  claim 1 ,
 wherein the fibers are fibers in a fibrous web, and the binder resin, the polishing particles and the pores are contained in the fibrous web.   
     
     
         4 . The polishing pad according to  claim 3 ,
 wherein the binder resin is a thermoplastic polyurethane resin, and the fibers are polyethylene terephthalate fibers or polypropylene fibers.   
     
     
         5 . The polishing pad according to  claim 4 ,
 wherein the binder resin is in a range from 8.5 to 12.7 vol %, the polishing particles are in a range from 10.6 to 14.8 vol %, the fibers are in a range from 17.4 to 26.1 vol %, and the pores are in a range from 54.0 to 58.6 vol %.   
     
     
         6 . The polishing pad according to  claim 5 ,
 wherein a value calculated by dividing the volume percent of the polishing particles by the total of the volume percent of the binder resin and the volume percent of the fibers is in a range from 0.30 to 0.48.   
     
     
         7 . The polishing pad according to  claim 3 , wherein:
 a density is in a range from 0.66 to 0.74 g/cm 3 ;   a durometer hardness is in a range from 30 to 38; and   an elastic modulus is in a range from 93.4 to 257.5 N/mm 2 .   
     
     
         8 . A wafer notch polishing method comprising:
 a first step of preparing a wafer, a polishing pad, and a polishing liquid; and   a second step of polishing the wafer with the polishing pad while supplying the polishing liquid between the wafer and the polishing pad,   wherein:   the wafer has: a central axis; a front surface that extends in a direction substantially orthogonal to the central axis; a rear surface that is positioned opposite to the front surface and extends in the direction substantially orthogonal to the central axis; and a notch that is formed by cutting out a portion of the wafer from the front surface to the rear surface and indicates an orientation of a crystal axis;   the polishing pad is formed in an annular shape and is centered on a first rotation axis center;   the polishing pad has: an annular first surface that extends in a direction substantially orthogonal to the first rotation axis center; an annular second surface that extends in the direction substantially orthogonal to the first rotation axis center and is positioned opposite to the first surface; and a polishing surface that connects the first surface and the second surface on an outer circumference of the polishing pad;   the polishing surface is formed of a polishing body that includes: a base material composed of a binder resin and fibers and having a plurality of pores formed therein; and polishing particles retained in the base material or in the pores; and   in the second step, the first rotation axis center is caused to be orthogonal to the central axis, the polishing liquid containing none of the polishing particles is used, and the polishing pad rotates around the first rotation axis center while pressing the polishing surface against the notch.   
     
     
         9 . The wafer notch polishing method according to  claim 8 ,
 wherein, in the second step, a distance between the front surface or the rear surface and the first rotation axis center is caused to change.