REACTOR MODELING FOR RADIO-FREQUENCY PLASMA DEPOSITION OF SINXHY - COMPARISON BETWEEN 2 REACTOR DESIGNS

Plasma deposition processes involve complex phenomena which make the d esign and optimization of industrial equipments difficult. In the part icular case of silane-ammonia plasmas to produce silicon nitride (at v ery low silane percentage), two flow arrangements, i.e., (i) a longitu dinal flow reactor and (ii) an axisymmetric showerhead electrode react or were studied by two-dimensional modeling of momentum and mass trans port. First, a kinetic scheme which enables us to reproduce experiment al results for both reactor configurations was selected enlightening a n unusual behavior of Si(NH2)(3) radicals. Then, the way silane is con sumed and its consequences on active species production was outlined a s playing the leading parts in the processes. As silane concentration decreases along the flow direction, the modeling of the longitudinal f low reactor shows a steep decrease of the deposition rate and a signif icant composition variation of the deposit. In the axisymmetric reacto r, the film thickness and composition uniformities considerably improv e due to the distributed gas feed. (C) 1996 American Vacuum Society.