The effect of the H2/(H2 + Ar) flow-rate ratio on hydrogenated amorphous carbon films grown using Ar/H2/C7H8 plasma chemical vapor deposition

To produce hydrogenated amorphous carbon (a-C:H) films with high mass density at a high deposition rate and low substrate bias voltage, we deposited these films on a Si substrate by plasma chemical vapor deposition, using toluene as a source compound and varying the gas flow-rate ratio of H2/(H2 + Ar). By decreasing the gas flow-rate ratio from 55% to 11%, the hydrogen content in the films decreased, and the density of sp3 carbon atoms in the films increased, whereas their surface roughness increased. At the gas flow-rate ratio of 11%, we produced a-C:H films with a high bulk density of 1830 kg/m3 at a high deposition rate of 81.1 nm/min.