流量及温度对低频PECVD氮化硅薄膜性能的影响

Influences of Gas Flow Ratio and Substrate Temperature on the Characteristics of Silicon Nitride Films Prepared by Low-frequency PECVD Technology

研究了低频等离子增强化学气相沉积(LF-PECVD)工艺中气体流量比和衬底温度对氮化硅薄膜折射率、密度及应力的影响规律,同时测试了薄膜的红外光谱以分析不同条件对薄膜成分的影响。结果表明,低频氮化硅薄膜折射率主要受薄膜内硅氮元素比的影响,其次是薄膜密度的影响。前者主要由硅烷/氨气反应气体流量比决定,而后者主要由衬底温度决定;低频氮化硅薄膜应力大致与密度成正比关系。此外,PECVD工艺所制备氮化硅薄膜都含有相当数量的氢元素,而衬底温度是薄膜内氢含量的决定因素。

The influences of gas flow ratio and substrate temperatures on the refractive index（RI）,density and stress of silicon nitride films prepared by low frequency（LF） plasma enhance chemical vapor deposition（PECVD） were thoroughly studied.The Fourier transform infrared spectrometry（FTIR） were employed to analyze thin film components under different preparation conditions.Results showed that,RI of LF PECVD silicon nitride film was mainly affected by Si/N atoms ratio in the film which depends on silane/ammonia gas ratio,and,secondly,by film density,which depends on substrate temperature.The stress of silicon nitride film is roughly proportional to film density and accordingly,silicon-rich nitride film has less compressive stress than nitrogen-rich film since the former has a lower density.In addition,silicon nitride films prepared by PECVD always contain relatively large amount of hydrogen,which is mainly decided by substrate temperature.