SiH_4/H_2等离子体气相生长硅薄膜的动力学模型

A kinetic model for silicon film growth by silane/hydrogen glow discharge

在化学气相沉积微晶硅薄膜过程中,为了降低成本,必须提高生长速率,但薄膜的微观结构和光电性能则随之降低,原因是成膜先驱物在薄膜表面上的扩散长度降低了.本文利用量子化学的反应动力学理论建立有关成膜先驱物SiH3和H的反应平衡方程,求解薄膜生长速率和成膜先驱物的扩散长度,并找出影响生长速率与扩散长度的微观参数,发现生长速率不仅与流向衬底的SiH3的通量密度有关,而且与H的通量密度有关;SiH3的扩散长度与衬底温度和薄膜表面的硅氢键的形态有关,当薄面表面被Si—H覆盖时,SiH3扩散长度较大,当薄面表面被Si—3H覆盖时,扩散长度较小,当薄面表面被悬键覆盖时,扩散长度趋于零.

During the process of plasma enhanced chemical vapor deposition,the growth rate of microcrystalline silicon films must be improved to reduce manufacture cost.With the increase of growth rate,the photoelectrical properties of such films will be greatly decreased.The main cause is the diffusion length of the precursors on the film surface decreases.In this study,a quantitative kinetic model was developed and the reaction balance equations of SiH3 and H were constructed,and the deposition rate,diffusion length and their influencing factors were obtained.We find that the deposition rate is determined by the fluxes of both SiH3 and H.The diffusion length of precursors is determined by the substrate temperature and the configuration of the surface silicon-hydrogen bonds.The diffusion length has a higher value when the growing film surface is covered by mono-hydrides,it has a smaller value when covered by tri-hydride,and it has a value close to zero when covered by dangling bonds.