GOODNESS OF FIT IN SPECTROGRAPHIC MONITORING OF A SUBSTRATE DURING PROCESSING

摘要

A sequence of current spectra is obtained with an in-situ optical monitoring system, and each current spectrum is compared to a plurality of reference spectra from a plurality of reference spectra libraries. The library that provides a best fit to the sequence of current spectra is determined, and a polishing endpoint is determined based on the sequence of current spectra and the library that provides a best fit to the sequence of current spectra. First and second sequences of current spectra of reflected light can be received from first and second zones of a substrate. Each current spectrum from the first and second sequence of current spectra is compared to a plurality of reference spectra from first and second reference spectra libraries, respectively, to generate first and second sequences of best match reference spectra, respectively. The second reference spectra library is distinct from the first reference spectra library.