Patent ID: 6932671

Claim:
A method for controlling a chemical mechanical polishing (CMP) operation in a multi-variable CMP apparatus that includes a plurality of end point detection probes, the method comprising the steps of: obtaining a thickness profile of a first layer overlying a first work piece; estimating an expected removal rate profile for the first layer; calculating a predicted clearing time profile for the first layer based upon the thickness profile and the expected removal rate profile; determining an expected range of radial position for each of the plurality of end point detectors during a CMP operation; calculating an expected probe detection time for each of the plurality of end point detection probes based on the clearing time profile and the expected range of radial position; setting each variable of the multi-variable CMP apparatus to a first setting; polishing the first layer overlying the first work piece; measuring an actual probe detection time for each of the plurality of end point detection probes; calculating a time correction coefficient relating actual probe detection time to expected probe detection time for each of the plurality of end point detection probes; and constructing an actual removal rate profile based on the expected removal rate profile and the calculated time correlation coefficients.