Optical heterodyne surface profiling interferometer with automatic focusing

Hongzhi Zhao; Rong Liang; Yongjun Wu; Dacheng Li; Mang Cao

doi:10.1117/12.284032

18 August 1997 Optical heterodyne surface profiling interferometer with automatic focusing

Hongzhi Zhao, Rong Liang, Yongjun Wu, Dacheng Li, Mang Cao

Proceedings Volume 3185, Automatic Inspection and Novel Instrumentation; (1997) https://doi.org/10.1117/12.284032
Event: ISMA '97 International Symposium on Microelectronics and Assembly, 1997, Singapore, Singapore

Abstract

In modern semiconductor and optics industries, there is a strong demand for a highly sensitive and non-contact surface profilometer. This paper describes an optical heterodyne surface profiling interferometer with automatic focusing which has been developed recently. The essential feature of the profilometer is a newly designed common-path method to minimize the effects of environmental conditions. A powerful signal processing scheme is also developed, which includes three parts: automatic voltage control, phase measurement and automatic focusing control. All these make the repeatability and stability of the profiling interferometer greatly improved. The height resolution is 3.5 nm and lateral resolution is 0.4 micrometers . Experiments show that the profiling interferometer is suitable for on-line use.

Citation Download Citation

Hongzhi Zhao, Rong Liang, Yongjun Wu, Dacheng Li, and Mang Cao "Optical heterodyne surface profiling interferometer with automatic focusing", Proc. SPIE 3185, Automatic Inspection and Novel Instrumentation, (18 August 1997); https://doi.org/10.1117/12.284032

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