High-accuracy simultaneous measurement of surface profile and film thickness using line-field white-light dispersive interferometer

Tong Guo, Guanhua Zhao, Dawei Tang, Qianwen Weng, Changbin Sun, Feng Gao, Xiangqian Jiang

Research output: Contribution to journalArticle

Abstract

White-light dispersive interferometry (WLDI) is an instantaneous, high-resolution optical metrological technique for measuring precise and complicated surfaces. This method enables nondestructive inspection of transparent-film-structure devices that are widely used in semiconductor packaging. We propose in this paper to use a home-built WLDI system with line-by-line spectral calibration, phase-shifting algorithm, and single-wave-number method for high-accuracy, simultaneous measurements of surface profiles and film thickness. By calibrating the relationship between wave-number and pixel position on each line of a two-dimensional detector, the line-by-line calibration method improves the measurement accuracy by correcting the spectral distortion caused by the optical system. Moreover, the spectral signal phase is obtained by the phase-shifting algorithm instead of by the Fourier transform method. The single-wave-number method is applied to the computation process by introducing the fringe order, and the measurement result indicates that it enhances the system immunity to environmental noise. A 1.806-μm-high standard step and a 1052.2-nm-thick standard film are measured to verify the system performance and show that the system is highly accurate and reliable.

Original languageEnglish
Article number106388
Number of pages8
JournalOptics and Lasers in Engineering
Volume137
Early online date24 Sep 2020
DOIs
Publication statusE-pub ahead of print - 24 Sep 2020

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