Patent ID: 7842621

Claim:
A method of measuring a nitrogen concentration in a silicon oxynitride film obtained by nitriding a silicon oxide film formed on a surface of a measurement target substrate, comprising: measuring a total film thickness T 1 N of the silicon oxynitride film and the silicon oxide film remaining thereunder; reoxidizing the measurement target substrate; measuring a total film thickness T 2 N of the silicon oxynitride film, the silicon oxide film and a reoxidized silicon oxide film formed on the measurement target substrate after reoxidizing the measurement target substrate; reoxidizing a reference substrate having a silicon oxide film formed thereon independently of the measurement target substrate; measuring a total film thickness T 2 of the silicon oxide film and a reoxidized silicon oxide film formed on the reference substrate after reoxidizing the reference substrate; calculating a reoxidation rate reduction ratio of the measurement target substrate from the total film thicknesses T 1 N, T 2 N and T 2 by using Equation 1; and determining the nitrogen concentration in the silicon oxynitride film on the measurement target substrate based on the calculated reoxidation rate reduction ratio, wherein Equation 1 is as follows: RORR (%)={( T 2 −T 2 N )/( T 2 −T 1 N )}×100.