Abstract
The thermal stability of amorphous SiNxCy films prepared by the plasma CVD method was described. The compositions of the films prepared were SiN1.34(-Si3N4), SiN0.75C0.43(SiNC) and SiC0.92(-SiC). The films were analyzed by infrared absorption spectroscopy (IR), thermal analysis (DTA/TG), X-ray diffraction, TEM, SEM and Auger electron spectroscopy to investigate the effect of annealing on the structure, bonding, crystallization temperature and crystalline phases. Hydrogen in films was desorbed on annealing from room temperature to 1173K. The loss of hydrogen, which was affected by the ambient atmosphere, was larger in vacuum than in N2. The crystallization temperatures of Si3N4, SiNC and SiC films were above 1673K, 1673K and 1373K when annealed in N2, and above 1373K, 1573K and 1273K when annealed in vacuum, respectively. The crystalline phases formed during annealing in vacuum were α, β-Si3N4 for Si3N4 films, α, β-Si3N4 and α, β-SiC for SiNC films, and β-SiC (α-SiC above 1673K) for SiC films. It was revealed that the SiNC film, a mixed composition of Si3N4 and SiC, had the highest crystallization temperature and thermal stability among them in spite of the absence of stable phases between Si3N4 and SiC. As for the thermal stability in morphological change (the occurrence of peelings and cracks on annealing) for Si3N4, SiNC and SiC films on the several kinds of substrates (stainless steel, carbon steel, Si, Si3N4, Al2O3), the Si3N4 film on stainless steel was superior to the other films on each substrate.
