A Miniaturized and Fast System for Thin Film Thickness Measurement

Abstract

Transparent films are significant industrial components that are widely used in modern optics, microelectronics, optical engineering, and other related fields. There is an urgent need for the fast and stable thickness measurement of industrial films at the micron-grade. This paper built a miniaturized and low-cost film thickness measurement system based on confocal spectral imaging and the principle of thin-film spectral interference. The reflection interference spectrum was analyzed to extract the phase term introduced by the film thickness from the full spectrum information, where local spectral noise can be better corrected. An efficient and robust film thickness calculation algorithm was realized without any calibrating sample. The micron-grade thickness measurement system had an industrial property with a measurement range of up to 75 μm with a measurement uncertainty of 0.1 μm, presenting a good performance in single-layer film thickness measurement with high efficiency.