R. Polini et al., Diamond synthesis on silicon nitride by the hot filament chemical vapor deposition technique, J CERAM S J, 106(12), 1998, pp. 1167-1171
Diamond films have been deposited by hot filament chemical vapor deposition
on hot-pressed silicon nitride substrates using a mixture of hydrogen and
methane with a CH4/H-2 volume ratio fixed to 0.5%. Scratching with diamond
paste of the as-received substrates was necessary to obtain high nucleation
densities (10(8)-10(9) cm(-2)) in the 750-1000 degrees C deposition temper
ature range, while, on scratched substrates, the nucleation density decreas
ed at 1050 degrees C, The diamond deposition rate has its maximum at around
850-900 degrees C. The film texture was {111} [100] at the low deposition
temperatures, while became {111} {100} [110] at temperatures higher than 75
0 degrees C. A careful analysis of the Raman spectra allowed us to identify
the best deposition conditions for the growth of high quality diamond. Sil
icon nitride as a substrate for diamond CVD is better than cemented tungste
n carbide due to the lower level of residual stress and to the higher phase
purity of the coating.