Patent ID: 9573242
Date: 2017-02-21
CPC Classifications: B24B,G01B,G01J,G01N,G05B,H01L

Claim:
1. A computer program product for controlling polishing, the computer program product tangibly embodied in a non-transitory computer readable medium and comprising instructions to cause a processor to: receive from an in-situ optical monitoring system, during polishing of a substrate that includes a non-metallic first layer undergoing polishing, a semiconductor second layer, and a third layer between the non-metallic first layer and the semiconductor second layer, a sequence of raw spectra of light reflected from the substrate; store a reference spectrum, the reference spectrum being a spectrum of light reflected from a same material as the third layer; normalize each raw spectrum in the sequence of raw spectra to generate a sequence of normalized spectra, wherein the instructions to normalize include a division operation in which the raw spectrum is in the numerator and the reference spectrum is in the denominator; and determine at least one of a polishing endpoint or an adjustment for a polishing rate based on at least one normalized predetermined spectrum from the sequence of normalized spectra.