2-DIMENSIONAL MODELING OF SIH4-H-2 RADIOFREQUENCY DISCHARGES FOR A-SI-H DEPOSITION

A two-dimensional numerical code, including three fluid modules to acc ount for the description of electrical, thermal and chemical phenomena , has been developed for the modelling of hydrogenated amorphous silic on deposition from SiH4-H-2 radio-frequency glow discharges in a cylin drical PECVD reactor. The results of the model are compared to experim ental data, obtained by different diagnostic techniques. The calculate d radical densities are compared to those measured by threshold ioniza tion mass spectrometry, at the centre of the substrate; the calculated SIH density profile between the electrodes is compared to those measu red by laser-induced fluorescence and the radial distribution of the d eposition rate on the substrate is compared to profilometry measuremen ts. Globally, the model correctly predicts the main discharge characte ristics for experimental conditions normally used for amorphous silico n deposition in the dust-free regime. The moderate agreement between m odel and experiment occurring for the hydrogen-dominated condition can be attributed to the simplified surface kinetics adopted in the model .