Patent ID: 7234999

Claim:
A polishing apparatus for polishing a substrate, comprising: a polishing table having a polishing surface; a top ring having a first pressing portion for pressing a back surface of a substrate so as to press a front surface of the substrate against said polishing surface, and having a second pressing portion for being pressed against said polishing surface, with each of said first and second pressing portions being capable of independently applying a desired pressure; and a control unit for controlling pressures applied by said first and second pressing portions, said control unit having a memory for storing pressure distributions for pressing the front surface of the substrate against said polishing surface, with each of the pressure distributions corresponding to a combination of a first pressure applied by said first pressing portion and a second pressure applied by said second pressing portion, wherein said control unit is for calculating another pressure distribution which is to act on the front surface of the substrate, the another pressure distribution corresponding to an intended first pressure to be applied by said first pressing portion and an intended second pressure to be applied by said second pressing portion, and being based on a superposition of the pressure distributions stored in said memory.