氮化硅薄膜生长随时间演化过程及其特性研究

Growth Evolution of Silicon Nitride Film over Time and Its Characteristics

氮化硅SiNx薄膜凭借介电常数高和稳定性好的特点而被广泛应用于光电器件中,但薄膜的厚度对器件的性能有重要影响。针对此问题采用等离子体化学气相沉积技术,以高纯NH_(3)、N_(2)和SiH_(4)为反应气体,优化其他沉积参数,通过改变沉积时间来生长SiNx薄膜。用X射线衍射谱(XRD),紫外-可见光光谱(UV-VIS)、傅里叶变换红外光谱(FTIR)和扫描电镜(SEM)对薄膜结构进行表征,详细研究了沉积时间与薄膜厚度的关系以及沉积时间对薄膜性能的影响。试验结果表明:所制备的样品为非晶SiNx薄膜结构,薄膜厚度随沉积时间均匀增加;薄膜折射率随沉积时间的增加而增大,光学带隙基本不随时间变化。SEM测试结果表明,随着沉积时间增加,薄膜致密性与均匀性越来越好,氧含量也越来越少,说明薄膜致密性提高可以有效阻挡O原子进入薄膜,阻止后氧化现象的发生。

Silicon nitride(SiNx)films have been widely used in optoelectronic devices due to their high dielectric constant and good stability,but the thickness of silicon nitride films has an important effect on the performance of devices.In order to solve this problem,silicon nitride films have been grown by plasma enhanced chemical vapor deposition(PECVD)at 13.56 MHz on glass and N-type monocrystalline silicon substrate using high purity NH_(3),N_(2) and SiH_(4) as reactant gas sources by optimizing other deposition parameters and changing deposition time.The samples were characterized by X-ray diffraction(XRD),ultraviolet-visible(UV-VIS)light transmittance spectra,fourier transform infrared absorption spectroscopy(FTIR)and scanning electron microscope(SEM).The relationship between deposition time and film thickness and the effect of deposition time on film properties were studied in detail.The results show that the prepared samples are amorphous SiNx thin film structure and the crystallization is independent of deposition time.The thickness of the thin film increases uniformly with deposition time,the refractive index of the thin film increases with deposition time,and the optical band gap does not change with deposition time.SEM test results show that with the increase of deposition time,the film density and uniformity become better and better.Fourier transform infrared spectra show that the silicon/nitrogen ratio of the thin film does not change with deposition time,but the oxygen content decreases,indicating that the increased film density effectively prevents O atoms from entering the film and prevents the occurrence of oxidation after the thin film is deposited.The experimental results show that good optical properties and dense structure of silicon nitride films can be obtained by changing deposition time.