Patent ID: 7959492

Claim:
A disk-shaped substrate inner circumference polishing method for polishing an inner circumference of a disk-shaped substrate including a portion having an opening hole at the center thereof, comprising: inserting a brush having a shaft core into the portion having the opening hole of the disk-shaped substrate, wherein the shaft core of the brush is formed by twisting wires; fixing one end of the brush to a first rotating shaft and the other end of the brush to a second rotating shaft, with each shaft being provided at a mutually detached position and pulling at least any one of the one end and the other end of the brush and applying tension in an axial direction to the shaft core of the brush, and wherein both shafts are positively driven; synchronously rotating the rotating shafts by positively driving the rotating shafts by a mechanical connection of the rotating shafts with a single motor, or by controlling individual motors provided to each rotating shaft; rotating the brush and polishing the inner circumference of the disk-shaped substrate; pulling the brush out from the disk-shaped substrate; inserting a second brush of which bristles are shorter and harder than the bristles of the brush into the portion having the opening hole of the disk-shaped substrate; fixing one end of the second brush to one of the rotating shafts and the other end of the second brush to the other rotating shaft, pulling at least any one of the one end and the other end of the second brush, and applying tension in the axial direction to a shaft core of the second brush; and rotating at least any one of the second brush and the disk-shaped substrate, and polishing the inner circumference of the disk-shaped substrate.