US Patent 12068189 Elastic membrane, substrate holding device, and polishing apparatus

An elastic membrane to be used for a polishing head includes a contact portion configured to come into contact with a wafer, an annular side wall provided to stand on an outer peripheral end of the contact portion, a first partition wall linearly extending inward in a radial direction in sectional view from the side wall, and a second partition wall linearly extending inward and upward in the radial direction in sectional view from an outer peripheral end portion of the contact portion, wherein the first partition wall, the second partition wall, and the side wall constitute an edge pressure chamber for pressing an edge of the wafer.