Method to measurement of the thin film thickness based on digital Moiré technique

Jun-hong Su; Yi-chen Liu

doi:10.1117/12.973675

15 October 2012 Method to measurement of the thin film thickness based on digital Moiré technique

Jun-hong Su, Yi-chen Liu

Proceedings Volume 8417, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment; 841713 (2012) https://doi.org/10.1117/12.973675
Event: 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2012), 2012, Xiamen, China

Abstract

Optical interferometry is the most accurate known method to measurement of the thin film thickness. With phase shifting interferometry (PSI) can achieve fast automatic measurement of the thin film thickness, however, this method requires high-precision phase shifter, such as PZT phase shifter, to the introduction of phase shift. This paper will use Digital Moiré technique to obtain the information of the thin film thickness by processing and analysis a static interferogram. The static interferogram with a certain spatial frequency introduced by the interferometer, then a virtual sinusoidal grating with this spatial frequency is generated in the computer. By changing the initial phase of the sinusoidal grating, π/2 phase shift between adjacent sinusoidal gratings will be made accurately. 4 sinusoidal gratings are obtained in a grating period, then overlapped these 4 sinusoidal gratings on the interferogram to get 4 moiré patterns. Processing and analysis the moiré patterns then the thin film thickness can be obtained by 4-bucket algorithm. In this method, the static interferogram is analyzed with PSI algorithm but there is no need to have phase shifter. The phase shift is introduced mathematically to avoid the associated error.

Citation Download Citation

Jun-hong Su and Yi-chen Liu "Method to measurement of the thin film thickness based on digital Moiré technique", Proc. SPIE 8417, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 841713 (15 October 2012); https://doi.org/10.1117/12.973675

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