The chemical deposition of amorphous and polycrystalline silicon in $SiH_4-H_2$ system has been studied. The deposition temperatures between 873K and 1123K have been used in a atmospheric pressure cold-wall reactor.
It is found that the growth rate of silicon is mainly affected by $SiH_2$ which is product of the thermal decomposition of silane.
To investigate the role of $SiH_2$ in Si chemical vapor deposition, a gas phase chemical kinetic model is proposed. This model, which includes a 15-step elementary reaction mechanism for the thermal decomposition of silane, predicts chemical species concentration profiles near substrate. Under the conclusions of the above gas-phase chemical kinetic model, the surface kinetic reaction model is also proposed.
It is found that the experimental deposition rate and morphologies of deposits are well explained with these models.
The electrical and optical properties of the Si films were also studied with the deposition variables. The experimental results show that its properties are greatly affected by the structure transition and deposition mechanism.
