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.