非晶硅薄膜的LF-PECVD制备及椭偏表征

Spectroscopic Ellipsometry Study on Hydrogenated Amorphous Silicon Thin Films Deposited by Low Frequency PECVD

以SiH4为先驱气体,采用低频等离子体增强化学气相沉积(LF-PECVD)方法在Si衬底上制备了氢化非晶硅(a-Si∶H)薄膜。在薄膜沉积过程中,工艺参数将会影响非晶硅薄膜的沉积速率和光学性能。通过反射式椭圆偏振光谱仪(SE)研究了SiH4气体流量、工作压强和衬底温度等条件对氢化非晶硅沉积速率和光学性质的影响。实验结果表明,氢化非晶硅沉积速率随着SiH4流量、工作压强和衬底温度的改变而规律地变化。相比于SiH4流量和工作压强,衬底温度对折射率、吸收系数和折射率的影响更大。各工艺条件下所制备的非晶硅薄膜光学禁带宽度在1.61～1.77eV。

Hydrogenated amorphous silicon （a-Si· H） films were deposited by low- frequency plasma-enhanced chemical vapor deposition （PECVD） on silicon substrate using Sill4 as the precursor gas. The process parameters will influence the deposition rate and optical properties of the films, such as Sill4 gas flow, working pressure and substrate temperature. The effect of these technical factors on deposition rate and optical properties was studied by spectroscopic ellipsometry. The experimental results show that the deposition rate of hydrogenated amorphous silicon increases with the increasing Sill4 gas flow, working pressure and substrate temperature. Compared to the effects of Sill4 flow and process pressure, the substrate temperature obviously affects the refractive index, absorption coefficient and optical bandgap. And the optical bandgap of the deposited a-Si · H varies from 1.61 to 1.77 eV.