小波变换表征多层膜氧化层、界面层和膜厚漂移

Applications of the Wavelet Transform to Characterize the Oxide Layer,Interlayer and Thickness Fluctuation in Multilayer Structures

用小波变换的方法分析了纳米多层膜的X射线掠入射反射率测试曲线.从小波变换的自相关函数峰位和峰强度信息中得到了常规曲线拟合方法难以表征的含有氧化层、界面层或厚度漂移的多层膜结构,利用其作为多层膜的初始结构再进行常规的曲线拟合,可实现多层膜结构精确表征的目的.研究成功地鉴别出钒单层膜的表面存在约3 nm厚的氧化层,分析得到Mo/Si多层膜的界面纯粗糙度约0.42 nm,表明在Ni/C多层膜中接近表面和基底的膜层存在大于5%的厚度漂移.

Wavelet transform is used to analyze the grazing incidence X-ray reflectivity curve of nanometer multilayer structures. For the structures including oxide layers,interlayers or thickness fluctuations,which are difficult to determine, wavelet transform can be used to get structure parameters from the peak positions and peak intensities of auto-correlation functions. Using these results as initial model of further curve fitting, the multilayer structures can be characterized accurately. The oxide layer of vanadium monolayer is determined to be about 3nm,the interfacial roughness of Mo/Si multilayer structures is about 0.42nm,and the results show that the thickness fluctuations of layers close to surface and substrate are over 5 %.