Thickness measuring apparatus, thickness measuring method, and wet etching apparatus and wet etching method utilizing them

Abstract

At each measurement time, measurement light is supplied from a measurement light source, and interference light obtained when reflected light from a semiconductor wafer W and reference light from a reference light generating sectionare coupled is detected by a photodetector. A thickness calculating sectionobtains a light intensity distribution representing the correlation between the light intensity of the interference light and the reference optical path length, selects a wafer upper surface peak and wafer lower surface peak from a plurality of light intensity peaks in the light intensity distribution using a predetermined selection criterion, and calculates the thickness of the semiconductor wafer W from the optical path length difference between the light intensity peaks. With this arrangement, a thickness measuring apparatus and thickness measuring method capable of measuring the thickness of a semiconductor wafer during execution of wet etching independently of the presence of an etchant, and a wet etching apparatus and wet etching method using the thickness measuring apparatus and method are implemented.