Surface topography measurement based on color images processing in white light interferometry

Microstructure surface topography is a key aspect of micro-nano measuring research for it has an obvious influence on the performance and quality of micro-nano devices. Scanning white light interferometry is a common method of testing surface profiling. In this paper, a color CCD camera, rather than a black-and-white CCD camera, was utilized to acquire white light interference images, which contain information of RGB channels. Based on acquired color interference images, wavelet transform method was employed to calculate phase value of corresponding channel in each scanning position. Then zero-optical-path-difference positions were accurately determined via a constructed evaluation function and least square method. Surface topography was eventually obtained via linear relationship of relative height and the zero-optical-path-difference position. The proposed method was verified by simulation and experiment of measuring standard step provided by VLSI Standards Incorporated.