Patent ID: 7714572
Filing Date: 2010-05-11
Classification: B24B,G01B,G01D,G01R

Abstract:
1. A method of detecting a continuous change in thickness of a first film and a second film subjected to polishing, the first film being formed on a substrate and the second film being formed on the first film, said method comprising: polishing the first film; during said polishing of the first film, supplying a sensor coil with a first alternating current having a first frequency for generating an eddy current in the first film to detect the thickness of the first film; measuring a first impedance across the sensor coil when the sensor coil is supplied with the first alternating current; detecting the thickness of the first film based on the first impedance; polishing the second film; during said polishing of the second film, supplying the sensor coil with a second alternating current having a second frequency for generating an eddy current in the second film to detect the thickness of the second film; measuring a second impedance across the sensor coil when the sensor coil is supplied with the second alternating current; and detecting the thickness of the second film based on the second impedance.