Influence of Annealing on the Structure and Mechanical Properties of PECVD Si-C-N Films

Structure, optoelectronic and mechanical properties of plasma-enhanced chemical vapor deposited silicon carbon nitride (Si-C-N) films at negative substrate biases Ud = – 5 V and – 250 V and annealed at $600^{\circ}C, 800^{\circ}C$, and 1000°C were investigated. All the deposited and annealed films are found to be X-ray amorphous. The as-deposited films at low and high Ud demonstrate one-and two-band photoluminescence, with the band maxima at 535 nm and at 560 nm, 640 nm, respectively. The hardness of the films increases with substrate bias from $\sim15$ GPa to $\sim37$ GPa. Annealing of the films obtained at low Ud shifts the PL band towards long wavelengths. For the films obtained at high Ud the PL band with a maximum at 560 nm shifts towards low wavelengths, and the band with a maximum at 640 nm shifts to the long-wavelength region. Annealing at $1000^{\circ}C$ in both cases leads to a quenching of PL. Si-C-N films deposited at low U}d demonstrate a slight decrease in the mechanical proporties with annealing, which indicates their thermal stability. Whereas, the high-biased Si-C-N films demonstrate a significant decrease of hardness even at low annealing temperatures.