RF discharge modelling in a N₂O/SiH₄mixture for SiO₂deposition and comparison with experiment

Abstract

The present work concerns the experimental and theoretical analysis of the electrical behaviour and N 2 O/SiH 4 dissociation of a classical RF discharge used for SiO 2 thin-film deposition. Electric and deposition rate measurements are undertaken at 0.5 and 1 Torr gas pressures. The reactor modelling involves electrical, hydrodynamic and mass transfer models. The electrical model enables the calculation of the electron impact dissociation rates required 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 - /SiH 4 and NO - /SiH 4 allows good agreement between the measured and calculated power densities particularly at 1 Torr. Furthermore, a simplified chemical scheme which includes 16 species (N 2 O, N 2 , O 2 , NO, NO 2 , N, O( 3 P), O( 1 D), SiH 4 , SiH 3 , SiH 3 O, H 2 SiO, H, H 2 , OH and H 2 O) is used in the mass transfer model. The corresponding results (deposition rates) are quite consistent with the measurements.