Influence of substrate dc bias on crystallinity of silicon films grown at a high rate from inductively-coupled plasma CVD

We have investigated the effect of substrate bias on the microcrystalline film growth from inductively-coupled plasma (ICP) of H2-diluted SiH4 at 250 °C to get an insight on the role of ion and electron incidence for the crystallization. By applying dc bias voltage to the substrate in the range of −20 ∼ 20 V during the film growth, the crystallinity is improved significantly with no significant change in the deposition rate, but in contrast the application of biases as high as ±50 V degrades the crystallinity. These results indicate that the incidence of ions or electrons with a moderate energy to the growing film surface promotes the nucleation and the growth of crystallites. Also, the optimum bias condition for the crystallization is changed with the antenna-substrate distance, which suggests the contribution of hydrogen radical flux to the crystalline film growth.