氢化硅薄膜的晶化机理研究

采用PECVD工艺制备了非晶，微晶和多形硅薄膜，研究了电极间热梯度对氢化硅薄膜结构的影响.根据拉曼光谱得到了微晶硅的晶化率，并在椭偏仪中用BEMA模型验证了其准确性.根据理论模型研究了热梯度对微晶和多形硅薄膜沉积机理的影响.研究薄膜厚度对晶化率的影响表明微晶薄膜底端和表面之间存在晶化梯度，而多形硅薄膜中无晶化梯度存在.采用Tauc-Lorentz模型拟合得到薄膜的结构参数表明非晶硅薄膜的致密度和有序度低，而多形硅和微晶硅薄膜的有序度、致密度相近，且明显高于非晶硅. 关键词： 氢化硅 晶化 热梯度 结构

Study on crystallization mechanism of hydrogenated silicon film

In this paper, amorphous, microcrystalline and polymorphous silicon films were prepared by plasma enhanced chemical deposition. Crystalline volume fraction of microcrystalline silicon was deduced from the Raman spectrum, and this fraction was validated using Bruggeman effective medium approximation (BEMA) model in spectroscopic ellipsometry measurement. The influence of thermal gradient on the deposition mechanism of microcrystalline and polymorphous silicon was investigated using a theoretical model. The dependence of crystalline volume fraction on film thickness shows there is a crystalline gradient between bottom and surface of microcrystalline film, and there is not such a gradient in polymorphous silicon film. Polymorphous and microcrystalline silicon have similar ordered state and density, which are signifieantly higher than those of amorphous silicon.