Chemical vapor deposition of silicon oxycarbide thin film by oxy-carbonization of silicon tetrahydride-carbon dioxide-ethylene mixtures

The objective of this study was to grow silicon oxycarbide thin films from chemical vapor deposition and to characterize the structure and chemical properties of the deposited films. The SiOxCy thin films were deposited from the oxy-carbonization of SiH4 with CO 2 and C2H4 in a horizontal hot-wall reactor. The concentration of carbon in the SiOxCy was controlled by the C2H4 flow in the fixed feed mixture. The deposition products from the oxy-carbonization were modeled by thermodynamic equilibrium calculations, and predictions of the model were compared to the experiments. The compositions and chemical structures were investigated by x-ray photoelectron spectroscopy. The structural evolution of the films was further evaluated by the combination of Fourier transform infrared spectroscopy, x-ray diffraction, and transmission electron microscopy. Typical HF chemical etching treatments were used to evaluate the chemical properties of the films.;Atomic concentrations varied from 29.0 to 39.0 at.% for silicon, 30.1 to 49.9 at.% for oxygen, and 11.0 to 40.9 at.% for carbon. Three different structures of films were observed: (1) SiO2-like film, (2) phase separated film (containing randomly distributed beta-SiC), and (3) amorphous SiOxCy film. The beta-SiC was randomly distributed In the films of intermediate carbon content (y/x 1) consisted of various oxycarbide species, which decreased oxygen bridges while increasing C-Si-C linkages. The carbon ratio (y/x) of the film also affected the chemical states of the oxycarbide, which were analyzed by the deconvoluted XPS Si 2p spectra. The silicon oxycarblde [SiOxC4-x] species increased with increasing carbon ratio (y/x), wherein there existed a compositional boundary (y/x = 1.0) which distinguished the amorphous oxycarbide phase from the film containing beta-SiC in SiO2. The HF etch rate of the films (y/x > 1) was minimized to 3∼5nm/hr when the films consisted only of the single-phase amorphous SiOxCy. Carbon rich species were the etch rate-determining species, and their contribution to the Si2p peak was increased with the decrease of oxygen rich species during etching of the film. When the carbon ratio is below this limit (y/x < 1), the film exhibited a two-phase structure which was readily attacked by HF.