Characterization of SiO_xN_y films deposited from SiCI₄ by remote plasma-enhanced chemical vapor deposition

Silicon oxynitride films have been deposited with SiCl₄ by remote-plasma enhanced chemical vapor deposition and a substrate temperature of 250°C. Different mixtures of O₂ and NH₃ were used to obtain different oxynitride compositions ranging from SiO₂ to a stoi-chiometry close to that of silicon nitride. Rutherford backscattering spectrometry was used to determine the stoichiometry of the SiO_xN_y, films. Also, the behavior of the IR absorption spectra as well as the refractive index measured by ellipsometry were used to estimate the effect of the different deposition parameters. It was found that the IR spectra show a shift of the characteristic peak associated with the stretching vibration mode of the Si-O-Si bonds towards lower wave numbers as the relative concentration of ammonia was increased with respect to oxygen. No double peaks associated with silicon oxide and silicon nitride were observed, indicating the formation of an homogeneous alloy. The IR spectra did not show any presence of water or hydrogen related impurities in the films. The effect of a hydrogen flow added during the deposition process on the films was studied. Atomic force microscopy measurements on these films show that the hydrogen flow added during deposition results in a reduction of the film roughness, which might be very significant for applications of silicon oxynitrides in very large scale integration microelectronics. Dielectric parameters as well as the dc conductivity of the films under the effect of an external sinusoidal electric field have been calculated in order to complete the structural characterization of the films.