Reactive Force-Field Molecular Dynamics Study of the Silicon-Germanium Deposition Processes by Plasma Enhanced Chemical Vapor Deposition

In order to form a SiGe thin film by chemical vapor deposition (CVD) with a suitable quality for advanced devices, the relationships between materials/process and structure/composition are needed to be clarified at the atomic level. We simulated SiGe CVD by using reactive force-field (ReaxFF) molecular dynamics simulations, especially on binary systems of SiHx + GeHx, and derived the influence of the substrate temperature and these ratios of gaseous species on the crystallinity and compositions in the thin films. The crystallinity increases as the substrate temperature increases, and the lowest crystallinity is obtained at the ratios of gaseous species 0.5 and 0.7 for the SiH3 and SiH2, respectively. As the substrate temperature increases, the hydrogen content decreases while Si and Ge content tend to increase. These trends can be seen in relevant studies. Through this simulation we successfully observe that the reactivity of gaseous species greatly affects the crystallinity and compositions in the thin films.