Amorphous hydrogenated silicon sub-oxide (α-SiOx∶H)is an excellent passivation material for sili-con wafer.In this paper,theα-SiOx∶H films were deposited to passivate n-type Cz-Si wafer by PECVD meth-od,SiH4 ,CO2 and H2 were used as precursors.The deposition pressure and the ratio of the CO2/SiH4 flow rate (RCO2/SiH4 )were optimized and their operation mechanisms on the passivation effect were analyzed.Quasi-steady state photoconductance method and spectroscopic ellipsometer were used to test the effective lifetime and imagi-nary part of the dielectric function (ε2 )of the passivated wafers.It was found that:(1)In this study,the doped oxygen in the films makes them amorphized.The operation mechanisms on the passivation effect of the two pa-rameters were different.Generally,the deposition pressure affects the void fraction in the films and RCO2/SiH4 af-fects the hydrogen fraction and structure.(2)The highest effective lifetime 975μs and the lowest surface re-combination 3.9 cm/s were gotten when RCO2/SiH4 was 3.0/3.0 mL/min and the deposition pressure was 22 Pa.%氢化非晶氧化硅(α-SiOx∶H)是一种优质的硅片表面钝化材料.采用PECVD法,以 SiH4、CO2和 H 2作为气源制备α-Si O x∶H 薄膜钝化 Cz-Si 表面,研究了沉积气压和CO2∶SiH4流量比对钝化效果的影响规律及作用机制.采用准稳态光电导法测试了硅片的有效少子寿命并依此计算出其表面复合速率以对薄膜的钝化效果进行定量表征,采用光谱型椭偏仪测试了样品的介电常数虚部ε2谱对样品微观结构进行了定性分析.结果表明,(1)在所研究范围内,氧掺入非晶硅薄膜使得薄膜结构趋向非晶化,沉积气压主要对薄膜中的空位浓度造成影响,而 CO2/SiH4流量比的增加可增加薄膜中的 H 含量并改变了硅氢键的结构,从而影响薄膜的钝化效果；(2)在 CO2/SiH4流量比为3．0/3．0 mL/min,沉积气压为22 Pa 条件下获得了最优钝化效果,钝化后硅片有效少子寿命为975μs,表面复合速率为3．9 cm/s.
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