Fitting of optical model to measured spectrum

摘要

A method of controlling a polishing operation includes 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, the parameters including an endpoint parameter and at least one non-endpoint parameter, the fitting generating a sequence of fitted endpoint parameter values, each endpoint parameter value of the sequence 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.

主权项

1. A method of controlling a polishing operation, comprising:
polishing a first layer of a substrate in a chemical mechanical polishing system; obtaining a measured spectrum with an optical monitoring system positioned in the chemical mechanical polishing system; fitting an optical model to the measured spectrum, the fitting including finding parameter values of parameters that provide a minimum of a difference between an output spectrum of the optical model and the measured spectrum, the parameters including an endpoint parameter and at least one non-endpoint parameter, the fitting generating a fitted endpoint parameter value and a fitted non-endpoint parameter value; and determining at least one of a polishing endpoint or an adjustment of a pressure for the chemical mechanical polishing system from the fitted endpoint parameter value.