Patent ID: 6923711

Claim:
An apparatus used in planarizing a wafer having a front surface, a leading edge, and a trailing edge, the apparatus comprising: a polishing pad having polishing surface; a platen adapted to support the polishing pad; a motion generator operably coupled to rotate the platen; an interferometer, comprising a light source positioned to sweep a light signal entirely across the wafer front surface from the wafer leading edge to the wafer trailing edge due to rotation of the platen, and a detector positioned to capture the light signal after reflecting off the wafer from surface; a multizone carrier adapted for pressing the front surface of the wafer against the polishing surface, said carrier comprising a plurality of concentric, independently pressurizable plenums, each of said plurality of plenums capable of containing a different, uniform pressure; a control system in communication with the interferometer and the multizone carrier for varying the pressure in each of said plurality of plenums.