A PIC-MC simulation of the effect of frequency on the characteristics of VHF SiH4/H2discharges

A 2D particle -in-cell and Monte Carlo code has been developed to study the behaviour of VHF discharges in a mixture of SiH4/H-2 at pressures below 300 mTorr and frequencies from 13.56 to 65 MHz. The aim of our study is to explain the increase of the deposition rate of thin amorphous films with the applied frequency which has been observed in various experiments. The frequency dependence of the electron energy distribution in the discharge area, the energy distribution of the ion fluxes to the substrate and the power dissipation are investigated at a constant power density. The experimentally observed increase of the deposition rate is explained by the fact that more ions are in an energy range which effectively influences the deposition process.