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Proceedings Paper

Ultrathin thickness and spacing measurement by interferometry and correction method
Author(s): Dongsheng Wang; Hongcheng Zhang; Yunping Yang; Yunxiang Zhang
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Paper Abstract

A measurement system utilizing interferometry and correction method has been developed to conduct fast and accurate measurement of ultrathin film thickness and spacing between two separated surfaces. According to the intensity of the interference pattern and the correction method, the ultrathin thickness or spacing is obtained exactly and quickly. After diffracted by a concave grating, the entire visible spectrum of the interference pattern is received simultaneously with a CCD array. Due to the numerical differentiation and average data processing method, the impacts of the light source, the reflecting surfaces, the grating and the CCD array are eliminated automatically. A numerical filtering technique used in the system significantly reduces the noise, thereby yielding a good signal to noise ratio. An ultrathin thickness of (lambda) /20 ((lambda) is the wavelength) is obtained by a numerical analysis of the measured data, which is remarkably less than the limitation, (lambda) /4, by the conventional method.

Paper Details

Date Published: 6 September 1995
PDF: 7 pages
Proc. SPIE 2542, Optomechanical and Precision Instrument Design, (6 September 1995); doi: 10.1117/12.218658
Show Author Affiliations
Dongsheng Wang, Tsinghua Univ. (China)
Hongcheng Zhang, Tsinghua Univ. (China)
Yunping Yang, Tsinghua Univ. (China)
Yunxiang Zhang, Tsinghua Univ. (China)

Published in SPIE Proceedings Vol. 2542:
Optomechanical and Precision Instrument Design
Alson E. Hatheway, Editor(s)

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