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6 September 1995 Ultrathin thickness and spacing measurement by interferometry and correction method
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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.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dongsheng Wang, Hongcheng Zhang, Yunping Yang, and Yunxiang Zhang "Ultrathin thickness and spacing measurement by interferometry and correction method", Proc. SPIE 2542, Optomechanical and Precision Instrument Design, (6 September 1995);

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