Patent ID: 9573244
Date: 2017-02-21
CPC Classifications: B24B

Claim:
1. An elastic membrane for use in a substrate holding apparatus, comprising: a contact portion to be brought into contact with a substrate for pressing the substrate against a polishing pad; a first edge circumferential wall extending upwardly from a peripheral edge of the contact portion; and a second edge circumferential wall having a horizontal portion connected to an inner circumferential surface of the first edge circumferential wall, wherein the inner circumferential surface of the first edge circumferential wall includes an upper inner circumferential surface and a lower inner circumferential surface, both of which are perpendicular to the contact portion, the upper inner circumferential surface and an upper surface of the horizontal portion defining a first edge pressure chamber, and the lower inner circumferential surface and a lower surface of the horizontal portion defining a second edge pressure chamber located below the first edge pressure chamber, the upper inner circumferential surface extends upwardly from the horizontal portion of the second edge circumferential wall, and the lower inner circumferential surface extends downwardly from the horizontal portion of the second edge peripheral wall.