Polishing apparatus, polishing brush and manufacturing method of disk-shaped substrate

1. A polishing apparatus that polishes an inner circumferential surface of a disk-shaped substrate including a portion having a hole at the center thereof, the polishing apparatus comprising:

a holding unit that holds piled workpieces in which a plurality of the disk-shaped substrates are piled;

a polishing brush that is inserted into the portion having the hole of the disk-shaped substrates of the piled workpieces and is rotated;

a cover member that covers the piled workpieces; and

a polishing-liquid flowing-in unit that flows polishing liquid into the portion having the hole of the disk-shaped substrates of the piled workpieces covered by the cover member, and

wherein the polishing flow-in unit flows fresh polishing liquid into a clearance between an inner circumference of the cover and an outer circumference of the piled disk-shaped substrates and the polishing liquid is supplied from an outer circumferential surface of the piled workpieces to the center portion having the hole.

2. The polishing apparatus according to claim 1 , wherein

the polishing brush comprises a shaft core, a brush base wound around the shaft core, and

a brush bristle bent and attached in a bundle to the brush base, and

the brush bristle is attached to the brush base by being bent so that one end side and the other end side of the bundle are put together.

3. The polishing apparatus according to claim 1 , wherein

the piled workpieces has a guide spacer between the piled disk-shaped substrates,

the guide spacer has a portion having a hole at the center thereof and a penetration portion that penetrates a portion between the portion having the hole and the outside thereof, and

the polishing-liquid flowing-in unit flows the polishing liquid into the portion having the hole of the disk-shaped substrate via the penetration portion of the guide spacer.

4. The polishing apparatus according to claim 3 , wherein

the cover member is formed so that the polishing liquid is led to the guide spacers along an outer circumferential surface of the piled workpieces.

5. The polishing apparatus according to claim 1 , wherein

the cover member covers the piled workpieces with a portion having a predetermined clearance between the outer circumferential surface of the piled workpieces and the cover member.

6. The polishing apparatus according to claim 5 , wherein the cover member is cylindrically formed and has a portion having a drain hole for the polishing liquid in the vicinity of one end of the cover member.

7. A polishing brush that is used for polishing of a disk-shaped substrate including a portion having a hole at the center thereof, the polishing brush comprising:

a shaft core;

a brush base wound around the shaft core; and

a brush bristle bent and attached to the brush base as a bundle,

wherein the brush bristle is attached to the brush base by being bent so that one end side and the other end side of the bundle are put together, and

wherein an angle θ is set so that both tip ends of the brush bristle are brought into contact with each other and are leaning against each other at the tip ends.

8. The polishing brush according to claim 7 , wherein the brush base to which the brush bristle is attached is wound spirally around the shaft core, and the one end side and the other end side of the brush bristle extend radially from the shaft core.

9. The polishing brush according to claim 7 , wherein

the polishing brush further comprises a core material that restricts bending of the brush bristle inside the bending of the brush bristle, and

the brush base attaches the brush bristle while wrapping the core material and the brush bristle.

10. The polishing brush according to claim 7 , wherein

the brush bristle as the bundle are bent in such a state that the one end side and the other end side of the brush bristle are concentrated toward the center part of the core material from the position restricted by the core material.

11. A manufacturing method of a disk-shaped substrate by polishing an inner circumferential surface of the disk-shaped substrate including a portion having a hole at the center, the manufacturing method of the disk-shaped substrate comprising:

a holding process that holds piled workpieces in which a plurality of the disk-shaped substrates to be polished are piled;

a covering process that covers an outer circumferential surface of the piled workpieces held by a cover member in the holding process; and

a polishing process that polishes the inner circumferential surface of the disk-shaped substrate by inserting a polishing brush into the portion having the hole of the disk-shaped substrates in the piled workpieces covered by the cover member and held in the holding process, rotating the polishing brush and flowing polishing liquid into the portion having the hole, and

wherein a polishing flow-in unit flows fresh polishing liquid into a clearance between an inner circumference of the cover and an outer circumference of the piled disk-shaped substrates and the polishing liquid is supplied from an outer circumferential surface of the piled workpieces to the center portion having the hole.

12. The manufacturing method of the disk-shaped substrate according to claim 11 , wherein

the polishing brush used in the polishing process comprises:

a shaft core;

a brush base wound around the shaft core; and

a brush bristle bent and attached to the brush base as a bundle, and

the brush bristle is attached to the brush base by being bent so that one end side and the other end side of the bundle are put together.

13. The manufacturing method of the disk-shaped substrate according to claim 11 , wherein

the holding process sandwiches a guide spacer including a portion having a hole at the center thereof and a penetration portion that penetrates a portion between the portion having the hole and the outside thereof between the piled disk-shaped substrates, and

the polishing process flows the polishing liquid into the portion having the hole of the disk-shaped substrate via the penetration portion of the guide spacer using the cover member.

14. The manufacturing method of the disk-shaped substrate according to claim 11 , wherein the disk-shaped substrates are attached to a substrate holder piling and holding the disk-shaped substrates in the holding process.