Epitaxial Layer Thickness Measurement by Far Infrared Ellipsometry

Abstract

This paper outlines the development of an ellipsometer operating at far ir wavelength (118.6 microm). The system has been used to measure thickness of n-type silicon epitaxial layers grown on heavily doped n-type silicon substrate. It is shown that the technique provides accurate measurements for both thick (>3-microm) and thin (<3-microm) epitaxial layers, and when used in conjunction with near ir interference measurements, a measure of junction grading is obtained.