Phenomenological and Elementary Reaction Analysis of Poly-crystalline Silicon CVD Process

Thickness uniformities of poly-crystalline silicon thin films, deposited by a commercial LPCVD reactor, were investigated through a phenomenological and elementary reaction analysis. To understand the deposition rate and its profile in radius direction of ø 6”h silicon wafer, concentration distributions of film precursors were examined by solving basic diffusion equations of film precursors in the CVD system. The experimental thickness distribution can be simulated very well with the solution by optimizing η, the sticking probabilities of the precursors. While most of the silicon deposition was made by source precursor (mono-silane, SiH4), two kinds of intermediate species with sticking probabilities of 5X10-2 and 7X10-4 were found to contribute the deposition. Subsequently, elementary chemical reaction analysis of poly-crystalline silicon CVD process was performed using ChemKinTM and two chemical species, SiH2 and Si2H6, were identified as the possible candidates for the intermediate species.