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-degrees-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.