Characterization of Si1-xGex Epilayer Thickness, Ge and Doped Boron Concentration with UV-Vis-IR Spectroscopic Ellipsometer

Abstract

Spectroscopic Ellipsometry (SE) is a non contact, non destructive approach based on the change of polarisation of light after reflection on a sample. SE allows the precise determination of the refractive indices and thicknesses of the films. With UV-Vis-IR spectroscopic ellipsometer, not only epilayer thickness and Ge concentration can be obtained with the UV-Vis channel, but also p-type dopant concentration with the IR channel. In this presentation, an alloy model will be introduced first to obtain Ge concentration. The principle to determine dopant concentration and electric properties of the film will be given secondly. With the advanced SOPRA ellipsometer tool, four types of samples were characterized, which are (a) single SiGe layer (Box), (b) SiGe layer with Si cap, (c) SiGe layer with graded Ge concentration and (d) Boron doped SiGe layer