Process modeling of stress and chemical effects in SiGe alloys using kinetic Monte Carlo

Abstract

In state-of-the-art silicon based process technologies, strained and relaxed SiGe, strained-silicon layers, and process-induced stress are widely present. Based on a literature review, we developed and calibrated continuum and kinetic Monte Carlo process models for chemical and stress effects in SiGe (Zographos et al. in AIP Conf. Proc. 1496:212---216, 2012). In this paper, we explain in full detail the corresponding kinetic Monte Carlo models and calibration. The models take into account the effects on band gap, amorphization, 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 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 have been calibrated for boron, arsenic and phosphorus taking into account that in experiments using epitaxial layers of strained SiGe embedded in Si, or strained silicon embedded in relaxed SiGe, boron and phosphorus have been found to segregate at Si/SiGe interfaces.