Patent ID: 9011202
Filing Date: 2015-04-21
Classification: B24B

Abstract:
1. A method of controlling a polishing operation, comprising: polishing a first layer of a substrate; during polishing, obtaining a sequence over time of measured spectra with an in-situ optical monitoring system; for each measured spectrum from the sequence of measured spectra, fitting an optical model to the measured spectrum, the fitting including finding parameters that provide a minimum difference between an output spectrum of the optical model and the measured spectrum, wherein the optical model includes dimensions of a repeating structure and the fitting includes calculating the output spectrum using diffraction effects of the repeating structure, the parameters including an endpoint parameter and a parameter of the repeating structure, the fitting generating a sequence of fitted endpoint parameter values, each endpoint parameter value of the sequence of fitted endpoint parameter values associated with one of the spectra of the sequence of measured spectra; and determining at least one of a polishing endpoint or an adjustment of a pressure to the substrate from the sequence of fitted endpoint parameter values.