Control of the gas phase and the surface reactions during the high rate synthesis of high quality microcrystalline silicon films: Effects of the source gas supply method and the substrate bias

In this article, to realize precise control of gas phase and surface reactions for high rate synthesis of high quality microcrystalline silicon (μc-Si) films, influences of source gas supply method and direct current (dc) substrate bias during film deposition process are investigated utilizing a microwave plasma source. It is found that the supply of SiH4 source gas near the substrate holder significantly enhances the deposition rate and mass density of deposited film and reduces film defect density while maintaining high crystallinity. On the other hand, a negative dc substrate bias induces film crystallization from the initial growth stage. An appropriate negative dc bias also leads to higher film cystallinity and density. Kinetics of the controlling gas phase and surface reactions through the optimizing source gas supply method and dc substrate bias is demonstrated. We claim that the high flux film precursor SiH3 and H along with less contribution of short-lifetime radicals on the film growing surface and ion-assist structural relaxation benefit the high-rate synthesis of high quality μc-Si films.