A modified Roberts-Langenbeck test for measuring thickness and refractive index variation of silicon wafers

Published

August 17, 2012

Author(s)

Jungjae Park, Lingfeng Chen, Quandou (. Wang, Ulf Griesmann

Abstract

We describe a method to simultaneously measure thickness variation and refractive index homogeneity of 300 mm diameter silicon wafers using a wavelength shifting Fizeau interferometer operating at 1550 nm. Only three measurements are required, corresponding to three different cavity configurations. A customized phase shifting algorithm is used to suppress several high order harmonics and minimize intensity sampling errors. The new method was tested with both silicon and fused silica wafers and measurement results proved to be highly repeatable. The reliability of the method was further verified by comparing the measured thickness variation of a 150 mm diameter wafer to a measurement of the wafer flatness after bonding the wafer to an optical flat.

Citation

Optics Express

Pub Type

Journals

Keywords

Instrumentation, measurement, and metrology, Interferometry, Optical inspection, Infrared and far-infrared lasers, Semiconductor materials.

Citation

Park, J. , Chen, L. , Wang, Q. and Griesmann, U. (2012), A modified Roberts-Langenbeck test for measuring thickness and refractive index variation of silicon wafers, Optics Express (Accessed December 13, 2025)