Kinetic study of silicon nitride growth from dichlorosilane and ammonia

The model of silicon nitride film deposition in a batch furnace from dichlorosilane (SiH2Cl2;DCS) and ammonia (NH3) is presented. The gas-phase and surface reaction rates of DCS are estimated from thickness profiles along the gas stream direction, and surface reaction and DCS decomposition are found to be of Langmuir and Lindemann types, respectively. It means that at a normal deposition temperature (similar to 1000 K); some DCS molecules adsorb directly on the Si surface while others decompose into a more reactive intermediate, SiCl2. At higher temperatures, the reverse reaction of DCS decomposition and the subsequent reaction of SiCl2 with NH3 may play significant roles. Using the present reaction rates, we estimate the film thickness profiles across a 12-inch wafer.