VHF-PECVD法高速率沉积氢化微晶硅薄膜

HIGH GROWTH-RATE DEPOSITION OF HYDROGENATED MICROCRYSTALLINE SILICON THIN FILM WITH VHF-PECVD

采用光发射谱(OES)技术对氢化微晶硅(μc Si∶H)薄膜的甚高频等离子体增强化学气相沉积(VHF PECVD)生长过程进行了原位监测,并对不同沉积条件下VHF等离子体中SiH 和H 的发光峰强度与薄膜沉积速率之间的关系进行了分析与讨论。通过Raman光谱、X射线衍射与扫描电子显微镜(SEM)测量,研究了μc Si∶H薄膜的结构特征与表面形貌。基于当前的沉积系统,对μc Si∶H薄膜沉积条件进行了初步优化,使μc Si∶H薄膜的沉积速率提高到2 0nm/s。

High growth rate deposition of μc-Si:H film with VHF-PECVD at low temperature(about 200°C) was studied. Investigations on different series showed that the growth rates were enhanced with higher excitation frequency and working pressure. However, with the increase of plasma power, growth rates were increased firstly and then decreased. Optical emission spectroscopy (OES) was introduced to monitor VHF plasma through the variations of the typical peak lines corresponding to SiH* and H*, and the relationship among growth rates and OES results has been discussed. The structural properties of μc-Si:H films were characterized with Raman spectra and X-ray diffraction(XRD), and Raman spectra were used to study the a-Si:H to μc-Si:H phase transition through changing silane concentration (Sc) and substrate temperature (Ts). The measuring results of scanning electron microscopy(SEM) revealed that the surface of μc-Si:H was columnar and with larger cluster for higher plasma power. Moreover, based on the analysis of the experimental results, a growth rate 2.0 nm/s was obtained through deposition conditions optimization.