Fundamental processes of microcrystalline silicon film growth: a molecular dynamics study

The fundamental processes of microcrystalline silicon film growth in plasma enhanced chemical vapor deposition (PECVD) with SiH4 gas diluted by H2 have been studied using molecular dynamics (MD) simulations with a realistic many-body semiclassical potential developed to describe interatomic interactions in the Si:H system. In this study the fundamental processes have been investigated from the following three viewpoints: (i) Si crystallization processes from SiH3 radicals; (ii) hydrogen desorption processes; and (iii) stability of the crystallized Si atoms. As a result of MD simulations related to these three points, it was found that when a substrate temperature is ca. 500 K, a SiH3 radical migrates to a crystalline Si site and is stabilized by bonding two surface Si atoms after releasing one H atom after ca. 200–300 ps, and that surface H desorption occurs as H2 molecules, SiH3 radicals and SiH4 molecules due to atomic H exposure. In addition it was observed that the stabilized Si atom in a crystalline Si site mentioned above cannot be etched by incident atomic H but unrelaxed Si atoms in surface layers can be etched.