Patent ID: 7981309
Filing Date: 2011-07-19
Classification: B24B,G01N,H01L

Abstract:
1. A method for detecting the polishing endpoint in a CMP polishing apparatus, comprising the following steps: (a) a step of finding in advance during CMP polishing the spectral reflectance spectrum of a reference wafer that has reached the polishing endpoint; (b) a step of finding the spectral reflectance spectrum of a sample wafer during CMP polishing, and finding a correlation coefficient with the spectral reflectance spectrum of the reference wafer that has reached the polishing endpoint found in step (a); (c) a step of finding, within the duration of CMP polishing, the sum of the absolute values of the difference at each wavelength, or the sum of the squares of the difference at each wavelength, between the first order differential with respect to the wavelength of the spectral reflectance spectrum found in step (a), and the first order differential with respect to the wavelength of the spectral reflectance spectrum found in step (b); (d) a step of determining the polishing endpoint to be the point at which the sum of the absolute values of the difference at each wavelength, or the sum of the squares of the difference at each wavelength, found in step (c) is at the minimum value within a range in which the correlation coefficient found in step (b) is equal to or greater than a specific threshold and; (e) a step of CMP polishing the sample wafer.