Experimental data vs. 3-D model calculations of HFCVD processes: correlations and discrepancies

An existing 3-D model [Mankelevich et al. Diamond Relat. Mater. 7 (1998) 11 33] has been used to explain experimentally measured spatially resolved CH; radical number densities in hot filament CVD reactors operating with both CH4/H-2 and C2H2/H-2 process gas mixtures and to examine in detail the proc ess of Ct tt C, inter-conversion in the gas phase. It has been shown that c ooler regions distant from the filament need to be modelled in order to obt ain the significant C-2 --> C-1 conversion observed in HFCVD reactors with C2H2/H-2 process gas mixtures. The origin and effect of the non-equilibrate d H, molecule vibrational state population distribution are studied for the first time in the context of HFCVD reactor models. (C) 2001 Elsevier Scien ce B.V, All rights reserved.