Silicon nitride chemical vapor deposition from dichlorosilane and ammonia: theoretical study of surface structures and reaction mechanism

The structure of a Si3N4 film and the mechanism of Si3N4 film growth along the [0 0 0 1] crystal direction during chemical vapor deposition have been examined using ab initio MP2/6-31G** calculations. The silicon nitride (0 0 0 1) surface and deposited (chemisorbed) species on this surface were described using cluster models. It was found that the dangling bonds of chemically bound Si and N atoms on the bare surface are relaxed to form additional π bonds or SiN surface double bonds. Energies of reaction and activation energies were calculated and the process of Si3N4 film growth was analyzed. It was found that the removal of chemically bound hydrogen from the surface is the rate-controlling step of the deposition process.