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 8C 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