Patent ID: 7271901

Claim:
A composition determining method for a compound semiconductor layer wherein the surface of a compound semiconductor layer formed on a substrate is measured using a spectroscopic ellipsometer, and the composition ratios x and y of said compound semiconductor layer formed on said substrate are determined, said composition determining method comprising: a spectrum measuring step for obtaining spectra Ψ E (λ i ) and Δ E (λ i ) by measuring a thin film on a substrate which is to be measured with various wavelengths of incident light, which represent the change in polarization of said incident light and the reflected light for each wavelength λ i ; a modeling spectrum calculating step wherein a model including said substrate with (N 0 (n 0 , k 0 )), and j-th layers with (d j , N j (n j , k j )), is formed, and modeling spectra Ψ M (λ i ) and Δ M (λ i ) are obtained based upon said model; a comparative evaluating step wherein comparison is made between said measured spectra Ψ E (λ i ) and Δ E (λ i ) and said modeling spectra Ψ M (λ i ), and Δ M (λ i ), and the structure corresponding to said modeling spectra Ψ M (λ i ) and Δ M (λ i ) satisfying predetermined evaluation criteria is determined as the measured result (d, n, k, and the composition ratio are determined); and a modifying step wherein said model not satisfying said predetermined evaluation criteria is modified, and processing in said modeling spectrum calculating step and processing in said comparative evaluating step are performed again.