氨气流量对富硅SiNx薄膜结构及其光学特性的影响

采用等离子体增强化学气相沉积技术,以NH3、SiH4和N2为反应气体制备富硅-氮化硅薄膜.在优化了其它沉积参数条件下,研究氨气流量对富硅-氮化硅薄膜的结构和光学性质的影响.利用傅立叶变换红外光谱、紫外可见光谱和X射线衍射谱分析了薄膜的键合情况、带隙结构.结果表明,随着NH3流量的增大,薄膜中的Si-N键和N-H键增强,Si-H键减小并向高波数方向移动,薄膜逐渐由非晶SiNx相向小晶粒Si3 N4相转变.同时随着NH3流量的增大,薄膜的光学带隙逐渐展宽,微观结构的有序度降低.XRD图谱分析表明薄膜内的平均晶粒尺寸也随着氨气流量的增加而在逐渐增大.结合以上结果分析,适当增加NH3流量有助于薄膜由非晶SiNx向包含小晶粒的Si3 N4转变.

Effect of NH3 Flow Rate on the Structures and Optical Properties of Silicon Rich SiNx Thin Films

With NH3 , SiH4 and N2 as reaction gas, silicon-rich nitride thin films were produced by plasma enhanced chemical vapor deposition method . In the case of optimizing other depositional parameters, the effects of NH3 flow rate were studied on the structures and on optical properties of silicon-rich SiNx thin films.The bonding situation and band gap structures of the film samples were analyzed by Fourier transform infrared absorption , ultraviolet-visible absorption spectrum and XRD .Its research result shows that with the increase of NH3 flow rate, the Si-N bond and N-H bond in the films are strengthened , but the Si-H bond is descended and moves to high wave-number.Meanwhile, the film transformation occurs from amorphous SiN x phase to small crystal Si3N4 phase .Besides , with the increase of NH3 flow rate, the optical band gap of the film is widened gradually and the order degree of the microscopic structures is decreased .In addition, the analysis of XRD pattern shows that the size of the average crystal grain in the films increases gradually with the increase of NH3 flow rate.Based on the above analysis , the conclusion comes that an appropriate increase of NH3 flow rate will contribute to the transformations of films from amorphous SiNx phase to small crystal Si3N4 phase.