Doping concentration control of SiGe layers by spectroscopic ellipsometry

Abstract

In this paper spectroscopic ellipsometry (SE) was applied for thickness and composition characterization of C and B doped SiGe layers grown on Si (100) by RPCVD at 600 °C. We present the effect of B doping (up to 1.2 × 10 21 cm − 3 ) and C incorporation (up to 0.7%) on optical constants dispersions of Si 1 − x Ge x (0 < x < 0.3) layers in the energy range 1.5–5.2 eV and their impact on thickness evaluation. We observed the changes of the positions of critical points and their broadening and found systematic monotonic changes for C incorporation in SiGe and nonmonotonic behaviour for B doped SiGe. The correlation between SE results and active boron concentration in the case of B incorporation was observed. The decoupling of the effect of C (or B) and Ge incorporation by SE was performed that can be applied in multi-dimensional lookup models for thickness and composition estimation and thus used for nondestructive characterization of SiGe-based materials.