Share Email Print

Proceedings Paper

Optical thickness measurement of substrates using a transmitted wavefront test at two wavelengths to average out multiple reflection errors
Author(s): Peter J. de Groot
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

I measure the optical thickness of thin substrates using a transmitted wavefront test in which the object is placed inside a Fizeau cavity comprised of a reference flat and a mechanically actuated transmission flat for phase shifting interferometry (PSI). Traditionally, this test had been complicated by the unwanted secondary reflections between the object surfaces even when the object is tilted. These reflections generate errors that are increasingly difficult to suppress as the substrate thickness decreases. The new technique involves two successive PSI measurements of the optical profile separated by a discrete change in source wavelength. The change in source wavelength is calculated so as to invert the error contributions from multiple surface reflections. Thus the average of the two measurements is relatively free of these error contributions.

Paper Details

Date Published: 20 June 2002
PDF: 7 pages
Proc. SPIE 4777, Interferometry XI: Techniques and Analysis, (20 June 2002); doi: 10.1117/12.472217
Show Author Affiliations
Peter J. de Groot, Zygo Corp. (United States)

Published in SPIE Proceedings Vol. 4777:
Interferometry XI: Techniques and Analysis
Katherine Creath; Joanna Schmit, Editor(s)

© SPIE. Terms of Use
Back to Top