Patent ID: 6872131

Claim:
A method for planarizing a microelectronic substrate, comprising: biasing a first annular part of the microelectronic substrate against a planarizing medium with a first force by engaging the first annular part with a first portion of a flexible membrane having a first thickness; biasing a second annular part of the microelectronic substrate against the planarizing medium with a second force greater than the first force by engaging the second annular part with a second portion of the flexible membrane having a second thickness greater than the first thickness, the second annular part located in a peripheral region of the microelectronic substrate and the first annular part located in a region of the microelectronic substrate outside the peripheral region, the substrate being held stationary relative to the membrane as the first annular part and the second annular part of the substrate is biased against the planarizing medium; and moving at least one of the microelectronic substrate and the planarizing medium relative to the other to remove material from the microelectronic substrate.