Effects of thin films on interferometric step height measurements

Thomas H. McWaid; Theodore V. Vorburger; Jun-Feng Song; Deane Chandler-Horowitz

doi:10.1117/12.139238

15 December 1992 Effects of thin films on interferometric step height measurements

Thomas H. McWaid, Theodore V. Vorburger, Jun-Feng Song, Deane Chandler-Horowitz

Proceedings Volume 1776, Interferometry: Surface Characterization and Testing; (1992) https://doi.org/10.1117/12.139238
Event: San Diego '92, 1992, San Diego, CA, United States

Abstract

Optical profiling instruments utilizing phase-shifting interferometry offer one the opportunity to obtain a large amount of surface texture data quickly without damaging the measured surface. Unfortunately, the presence of dissimilar surface materials or even spatial variations in the subsurface morphology can result in spurious optical measurements. This paper presents equations that can be used to calculate the reflection of electromagnetic radiation from thin film structures. These equations are utilized to determine what minimum metal overcoat thickness will ensure accurate optical step height measurements. Interferometric and stylus- based measurements of three thin film steps are presented and discussed. An opaque metal overcoat is found to be essential to the accurate optical measurement of step heights.

Citation Download Citation

Thomas H. McWaid, Theodore V. Vorburger, Jun-Feng Song, and Deane Chandler-Horowitz "Effects of thin films on interferometric step height measurements", Proc. SPIE 1776, Interferometry: Surface Characterization and Testing, (15 December 1992); https://doi.org/10.1117/12.139238

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