Modeling and experiments of high-pressure VHF SiH4/H2 discharges for higher microcrystalline silicon deposition rate

The effect of the total gas pressure (1–3 Torr) on the growth rate and the crystalline volume fraction (Xc) of films deposited from 70 MHz SiH4/H2 plasmas is investigated. The films were grown in conditions near the transition from microcrystalline to amorphous silicon growth at high deposition rates (10 Å/s). Simultaneously, a two-dimensional self-consistent fluid model of diluted SiH4 in H2 discharges was used to simulate the deposition process. The model integrates a detailed gas phase and surface chemistry including 25 species, 85 gas phase reactions and 27 surface reactions. A good agreement was found between model and experiments concerning the deposition rate. On this basis, the effects of pressure on the electron density and temperature, discharge impedance, electric field distribution as well as on the distribution and importance of the films precursors is discussed.