Model of a two-stage rf plasma reactor for SiC deposition

A reactor is proposed for plasma-enhanced chemical-vapor deposition of sili con carbide (SiC) at low pressure (similar to few Torr). The inductively co upled plasma lies upstream of the growth substrate and serves to dissociate the precursor silane/propane/hydrogen inlet gas. Unlike existing reactors, the design offers the potential for separate control of the temperature in the dissociation region and at the growth substrate. The geometrical param eters and flow conditions appropriate for SiC growth are analyzed with a on e-dimensional flow simulation model which includes approximations for later al diffusive losses to cold walls as well as deposition to the substrate. T wenty-one neutral species and 24 ions are followed with 179 reactions. At 3 Torr, 10 W/cm(3), and 300 cm/s inlet flow velocity, the model predicts a g rowth rate of similar to3 mum/h downstream from the plasma. Negligible ion density exists over the substrate as long as the silane density is sufficie ntly large due to a feedback process between Si+ and SiH4. Besides heating the gas, the plasma is an efficient source of radical H atoms, which in tur n control the abundance of some hydrocarbon species over the substrate. C2H 2 is the dominant contributor to the C-bearing flux onto the substrate and the Si atom, which forms by electron reactions, is the most important Si-be aring species. Finally, a sensitive transition in deposition rate is found for the C-bearing species as the power increases from 5 to 10 W/cm(3). (C) 2001 American Institute of Physics.