Chemical Structure and Growth Mechanism of a-Si<sub>x</sub>C<sub>1-x</sub>:H Films Prepared by Plasma Enhanced Magnetron Sputtering

Abstract

Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films were prepared by microwave electron cyclotron resonance (MW-ECR) plasma enhanced unbalance magnetron sputtering with a silicon target and CH4 as Si and C sources, respectively. The influence of CH4 flow rate and the deposition temperature on the chemical structure, stoichiometry, and hardness were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and nano-indentation. The results indicated that, as the CH4 flow rate increased from 5 to 45 cm3·min-1 (standard state), the amount of Si—CH2 groups and C—H groups increased constantly, but the number of Si—H groups did not change. The atomic concentration of C increases from 28% to 76% while Si decreases from 62% to 19%. The amount of Si—H and C—H groups in the deposited films decreases dramatically while the Si—C bonds and the hardness of the resultant films increase with an increase in deposition temperature at a constant CH4 flow rate. The atomic concentrations of Si and C remain almost constant at about 52% and 43%, respectively. The hardness of the deposited films with a constant CH4 flow rate of 15 cm3·min-1 increases to 29.7 GPa at a deposition temperature of 600 ℃. We propose a growth mechanism for the a-Si1-xCx:H films at room temperature (25 ℃) and at high temperature based on the characterization results.