Patent ID: 8579675

Claim:
A method of controlling the chemical mechanical polishing, comprising: polishing a substrate on a first platen using a first set of polishing parameters; obtaining a plurality of measured spectra from at least two zones of the substrate by in-situ optical monitoring during polishing; comparing the plurality of measured spectra with a reference spectrum to evaluate a thickness of each of the at least two zones of the substrate; comparing a thickness of a first zone of the at least two zones with a thickness of a second zone of the at least two zones; determining whether the thickness of the first zone of the at least two zones falls within a predetermined range of the thickness of the second zone of the at least two zones; and if the thickness of the first zone of the at least two zones does not fall within the predetermined range, at least one of a) adjusting at least one polishing parameter of the first set of polishing parameters and polishing a second substrate on the first platen using the adjusted polishing parameters, or b) adjusting at least one polishing parameter of a second set of polishing parameters and polishing the substrate on a second platen using the adjusted polishing parameters.