Patent ID: 7622052
Filing Date: 2009-11-24
Classification: B24B

Abstract:
1. A method for determining the endpoint of a CMP operation on a layer overlying a work piece, the method comprising the steps of: making a plurality of eddy current measurements of thickness of the layer during a CMP operation, each of the plurality of eddy current measurements spaced apart in time by a predetermined length of time; generating a diameter scan based upon the plurality of eddy current measurements; dividing the diameter scan into a plurality of zones, calculating a difference in thickness measured between sequential ones of the plurality of eddy current measurements in each of the plurality of zones; calculating a moving average of the differences in thickness for each of the plurality of zones; setting a minimum threshold for the moving average; and determining the endpoint of the CMP operation when the moving average is equal to or less than the minimum threshold in each of the plurality of zones; wherein the steps of making, generating, dividing, and calculating a difference in thickness are performed in a continuous loop until the endpoint of the CMP operation is determined.