Amorphous silicon carbide films by plasma-enhanced chemical vapor deposition

Plasma-enhanced chemical vapor deposition (PECVD) of amorphous silicon carbide (α-SiC) is studied. PECVD allows deposition of α-SiC on a variety of substrates at low temperatures. The index of refraction of the deposited α-SiC films was in the range of 1.9 to 2.4 depending on the SiH₄/CH₄ gas flow ratio and RF power. The deposition rate of α-SiC films, averaging 45 Å/min, increased with increasing RF power and pressure, and with decreasing substrate temperature. The quality of the deposited films could be improved by high-temperature annealing. The HF etch rate of the PECVD SiC films in HF is small enough (i.e., 5 Å/s on the average) to enable utilization of these films in surface micromachining processes which use silicon dioxide as a sacrificial layer