氢化非晶硅激光诱导结晶膜微结构的椭偏谱分析

Analysis of the Microstructure of Laser Crystallized Hydrogenated Amorphous Silicon Films by Spectroscopic Ellipsometry

用XeCl准分子激光器对氢化非晶硅（a－Si：H）薄膜进行了诱导晶化处理。测量了结晶膜的椭偏谱。利用多层膜模型与Bruggeman有效介质近似（B－EMA）分析了结晶膜的微结构特性。研究表明：低能量密度辐照形成的结晶层需用含有a－Si：H的EMA混合物表征，说明其结晶度相对较低；而高能量密度辐照形成的结晶层，因其结晶度较高，可用不含a－Si：H的EMA混合物表征．在结晶膜与衬底之间形成了互混层，其厚度随能量密度增大而增大。当能量密度较高时，结晶层会与互混层剥离．采用椭偏谱数据拟合得到Si浓度的深度剖面分布后，可据此重构结晶膜的三维表面形貌图．

Hydrogenated amorphous silicon (a-Si: H) films have been crystallized by the irradiations of XeCl excimer laser. The ellipsometric spectra of the crystallized films have been measured. Using multilayer model and Bruggeman effective medium approximation (B-EMA),we have analyzed the microstructure of thecrystallized films. The results show that, for low energy density,the crystallized layer should be characterized by the EMA mixture containing a-Si: H,which is an indication of relatively low crystallinity; whereas for high energy density,the crystallized layer having higher crystallinity can be characterized by the EMA micture containing no a-Si: H. An intermixing layer,whose thickness increases with the increase of the energy density,has been formed between the crystallized film and the substrate. For high energy density,the crystallized layer may peel from the intermixing layer. Using the Si depth profile obtained by fitting ellipsometric spectra data,the 3D surface morphology of the crystallized film can be reconstructed.