Preparation and characterization of low pressure chemically vapor deposited silicon nitride thin films from tris(diethylamino)chlorosilane and ammonia

To achieve amorphous silicon nitride (a-SiN_x) thin films with minimal incorporation of impurities such as carbon and hydrogen, a novel liquid source precursor, tris(diethylamino)chlorosilane (TDEACS), was developed. TDEACS and ammonia (NH₃) were used to produce a-SiN_x films by low pressure chemical vapor deposition in a hot wall tubular reactor. The growth kinetics was investigated as a function of total pressure, NH ₃/TDEACS flow ratio, and deposition temperature. The film compositions and topography were characterized by X-ray photoelectron spectroscopy, Auger depth profile, Fourier transform infrared spectroscopy, elastic recoil detection, and atomic force microscopy, respectively. The growth rate of the films follows an Arrhenius behavior with apparent activation energy of 182.6 kJ•mol^-1 between 600 and 750 °C. At NH ₃/TDEACS flow rate ratios below 4, carbon-containing a-SiN _x films were obtained while all films were stoichiometric with a N/Si atomic ratio 1.30-1.32 as the ratios beyond 6. Both carbon and hydrogen contents of the prepared a-SiN_x films were markedly lower than those prepared from other organic precursors previously reported. The surface topography of the films is smooth and uniform with a root mean square roughness value of 0.53 nm.