The effect of process parameters such as saw damage removal, gas dilution and silane depletion are studied to maximize the efficiency of silicon a-Si/c-Si heterojuction solar cells. Furthermore, the effect of chemical treatment and annealing are also studied to understand their effect on performance of silicon heterojunction solar cells. A smooth and defect free junction is required to exploit the heterojunction properties of the junction and produce high open circuit voltage. Hence a smooth c-Si surface and the incorporation and migration of hydrogen in the amorphous silicon layers, especially the intrinsic amorphous layer, are very important. The process parameters affecting these properties have been studied and direct relation between the process parameters and the cell performance has been found.