Process modeling of chemical and stress effects in SiGe

Strained and relaxed SiGe, strained-silicon layers, and process-induced stress are widely used in state-of-the-art silicon process technology. Based on a literature review, we developed and calibrated continuum and kinetic Monte Carlo (kMC) process models for chemical and stress effects in SiGe. The models take into account the effects on band gap, amorphization and recrystallization, point defect generation and diffusion, extended defect evolution, dopant diffusion and clustering, and dopant segregation. The influence of Ge concentration and strain profile on Si self-interstitials and vacancies properties are deducted from experimental data as well as from ab initio studies. The {311} interstitial clusters are less stable in the presence of Ge or of compressive hydrostatic pressure, and the transformation of {311} defects into dislocation loops is faster. The corresponding parameter adjustments have been calibrated based on experimental data generated within the ATOMICS research project. The effects of Ge and stress on dopant diffusion and solubility have been calibrated for boron and arsenic. Boron has been found to segregate at Si/SiGe interfaces, in experiments using epitaxial layers of strained SiGe embedded in Si, or strained silicon embedded in relaxed SiGe. Complementary models for continuum and kMC process simulation are proposed.