Effect of rapid thermal annealing on both the stress and the bonding states of a-SiC:H films

The stress evolution of plasma enhanced chemical vapor deposition a-SiC:H films was studied by increasing the annealing temperature from 300 to 850 °C. A large stress range from −1 GPa compressive to 1 GPa tensile was investigated. Infrared absorption, x-ray photoelectron spectroscopy, and elastic recoil detection analysis techniques were used to follow the Si-C, Si-H, and C-H absorption band evolutions, the Si2p and C1s chemical bondings, and the a-SiC:H film hydrogen content variations with the annealing temperatures, respectively. It is pointed out that the compressive stress relaxation is due to the hydrogenated bond (Si—H and C—H) dissociation, whereas the tensile stress is caused by additional Si—C bond formation. At high annealing temperatures, a total hydrogen content decrease is clearly observed. This total hydrogen loss is interpreted in terms of hydrogen molecule formation and outerdiffusion. The results are discussed and a quantitative model correlating the intrinsic stress variation to the Si—H, C—H, and Si—C bond density variations is proposed.