Polishing method

摘要

A method of polishing a substrate is disclosed. The method includes irradiating the substrate with light; measuring intensity of the reflected light; producing spectral waveform representing relationship between relative reflectance and wavelength of the light; performing a Fourier transform process on the spectral waveform to determine a thickness of the film and a corresponding strength of frequency component; determining whether the determined thickness of the film is reliable or not by comparing the strength of frequency component with a threshold value; calculating a defective data rate representing a proportion of the number of unreliable measured values to the total number of measured values; and changing the threshold value based on the defective data rate.

主权项

1. A method of polishing a substrate having a film, the method comprising:
polishing the substrate by pressing the substrate against a polishing tool on a rotating polishing table; irradiating the substrate with light when polishing the substrate; receiving the light reflected from the substrate; measuring intensity of the reflected light at respective wavelength, the reflected light having wavelengths of not more than 1100 nm; calculating relative reflectance by dividing the measured intensity of the light by predetermined reference intensity; producing spectral waveform representing relationship between the relative reflectance and wavelength of the light; performing a Fourier transform process on the spectral waveform to determine a thickness of the film and a corresponding strength of frequency component; and determining a polishing end point of the substrate based on a point in time at which the determined thickness of the film has reached a predetermined target value.