Diamond deposition from halogenated methane precursors on Si and SiC substrates

Abstract

Diamond films have been grown on Si and SiC substrates using the hot filament method and CF 4 , CCl 2 F 2 and CCl 4 as carbon precursor gases. It has been shown that the quality of the diamond films grown on Si substrates gets worse when the fluorine concentration increases in the precursor gas. This is due to aggressive etching of Si caused by HF, created thermally at the filament, which removes the diamond seeding nanocrystals and suppresses further diamond growth. Diamond growth is effectively prevented when CF 4 is used, but for CCl 4 there is a fully covering diamond film and no sign of etching. When the same gases are used on SiC however, there is a slight tendency towards higher quality as the fluorine content increases. SiC is more inert to HF and therefore the growth mechanisms will not be affected by etching to the same extent in this case. The slight increase in diamond quality with increasing fluorine content is believed to be due to preferential etching from HF of graphite.