Method of measuring a thickness of a multilayered sample using ultraviolet light and light with wavelengths longer than ultraviolet

摘要

Spectral reflection ratios with respect to a second wavelength range are obtained and Fourier transformed to derive frequency converted spectrum. A power spectrum is obtained from the frequency converted spectrum to identify a peak which expresses interference caused by a silicon film. An approximate value d2' of the film thickness of the silicon film is calculated based on the peak position. After filtered by low-pass filtering, the frequency converted spectrum is reverse Fourier transformed to obtain spectral reflectance. From the spectral reflectance, theoretical spectral reflection ratios which are theoretically derived on only one transparent film of the thickness d3 which is formed on a silicon layer are subtracted. An approximate value d1' of the thickness of a silicon oxide film is then calculated from the spectral reflectance which are obtained by subtraction.