Thin film thickness and refractive index measurement by multiple beam interferometry and fast spectral correlation method

The establishment and use of precision measurement technology and system become an important part to understand and to effectively control the materials, structures or installations in nano-scale. In this paper, a system based on the multiple beam interferometry, multi-matrix method and fast spectral correlation method is developed to measure the thickness and refractive index of thin film. Primary study to analyze the FECO images obtained from symmetrical three-layer (mica-air-mica) with film thickness over 200nm and non-symmetrical interference (mica- air- LDPE-mica) was made. The results show that the fast spectral correlation formula can be applied to both symmetric and non-symmetric three-layer interference, and the film thickness measurement is applicable to over 200nm.