Production of disilane and silyl sticking coefficients during plasma‐enhanced chemical vapor deposition of hydrogenated amorphous silicon

The rate of production of disilane (Si₂H₆) in silane (SiH₄) plasmas by gas phase and surface‐catalyzed processes is examined. The discussion is based on results from plasma chemistry and surface deposition computer models. The surface model simulates the adsorption of silane radicals from the plasma on a growing amorphous silicon film and the subsequent desorption from the surface of the nonadhering SiH₃ radicals as Si₂H₆. The rate of generation of Si₂H₆ from the surface reactions is compared to the rate of generation due to plasma reactions. We find that for conditions which are typical of those used for deposition of amorphous silicon, production of disilane is likely dominated by surface‐catalyzed processes. The rate of production, though, depends on the sticking coefficient of SiH₃, which we find to be a function of plasma conditions.