RF discharge modelling in a N2O/SiH4 mixture for SiO2 deposition and comparison with experiment

The present work concerns the experimental and theoretical analysis of the electrical behaviour and N2O/SiH4 dissociation of a classical RF discharge used for SiO2 thin-film deposition. Electric and deposition rate measuremen ts are undertaken at 0.5 and 1 Tarr gas pressures. The reactor modelling in volves electrical, hydrodynamic and mass transfer models. The electrical mo del enables the calculation of the electron impact dissociation rates requi red for the mass transfer model, while the gas velocities are determined by the hydrodynamic model. Only an electrical discharge model accounting for the negative-ion conversion reactions O-/SiH4 and NO-/SiH4 allows good agre ement between the measured and calculated power densities particularly at I Torr. Furthermore, a simplified chemical scheme which includes 16 species (N2O, N-2, O-2, NO, NO2, N, O(P-3), (O(D))-D-i, SiH4, SiH3, SiH3O, H2SIO. H , H-2, OH and H2O) is used in the mass transfer model. The corresponding re sults (deposition rates) are quite consistent with the measurements.