Effect of deposition temperature on the chemical properties of thermally deposited silicon nitride films

Silicon nitride (Si3N4) films have been deposited by using dimethyl dichloro silane (DMDS) as a source of silicon and ammonia (NH3) gas as a source of nitrogen at 760-860 °C deposition temperature by thermal-CVD system. An extensive analysis of the chemical properties of the films was carried out using Ellipsometry and Fourier Transform Infrared (FTIR) Spectroscopy measurements. The deposited silicon nitride films show the presence of hydrogen bonded to silicon and nitrogen. The relative number of Si-H, N-H, and Si-N bonds has been estimated and the Si-H, N-H and Si-N-Si stretching characteristic peaks of Si3N4 films have also been observed with significant intensities through FTIR spectroscopy as a function of deposition temperature. It has been found that films deposited in the temperature range of 760-860 °C, have some amount of hydrogen contents. The total hydrogen concentration in the films decreases with corresponding increase in deposition temperature, which reveals that the densification of deposited films increases on increasing the deposition temperature. The film properties including N-H/Si-H ratio, hydrogen content, and density of films are most sensitive to change in the deposition temperature.