FILM THICKNESS DISTRIBUTION MEASUREMENT METHOD

摘要

PROBLEM TO BE SOLVED: To provide a film thickness distribution measurement method that can quickly and highly accurately measure film thickness distribution of a wafer with two thin films by the reflection spectroscopy.SOLUTION: The film thickness distribution measurement method includes the steps of: (A) calculating a profile P1 which indicates wavelength dependence of reflectance ratio of a wafer with the thin films as a measuring object with respect to light in a wavelength region equal to or greater than visible light wavelength; (B) calculating a profile P21 which indicates wavelength dependence of reflectance ratio of a wafer with the thin films having a thinner or thicker second thin film than a set film thickness T2 of the second thin film of the wafer with the thin films, with respect to light in a wavelength region equal to or greater than visible light; (C)obtaining a wavelength λ1 when a profile P31 as a difference between the P1 and the P21 is zero; (D) selecting a wavelength band including the obtained wavelength λ1 as light wavelength band used for film thickness distribution measurement by the reflection spectroscopy; and (E) irradiating a surface of the wafer with the thin films as measuring object with light, and measuring the film thickness distribution of a first thin film by the reflection spectroscopy using as measuring object only reflection light of the selected wavelength band among light reflected from the surface of the wafer with the thin films.