Numerical Simulation of VHF E®ects on Densities of Important Species for Silicon Film Deposition at Atmospheric Pressure

The characteristics of homogeneous discharges in mixed gases of hydrogen diluted silane and argon at atmospheric pressure are investigated numerically based on a one-dimensional fluid model. This model takes into account the primary processes¡excitation and ionization, sixteen reactions of radicals with radicals in silane/hydrogen/argon discharges¡and therefore, can adequately represent the discharge plasma. We analyze the effects of very high frequency (VHF) on the densities of species (e, H, SiH₃, SiH⁺ ₃ and SiH₂) in such discharges using the model. The simulation results show that the densities of SiH₃, SiH⁺ ₃, H, and SiH2 increase with VHF when the VHF ranges from 30 MHz to 150 MHz. It is found that the deposition rate of ¹c-Si:H ¯lm depends on the concentration of SiH₃, SiH⁺ ₃, SiH2, and H in the plasma. The e®ects of VHF on the deposition rate and the amount of crystallized fraction for ¹c-Si:H ¯lm growth is also discussed in this paper.