扫描透射电子显微镜(STEM)在新一代高K栅介质材料的应用

Applications of Scanning Transmission Electron Microscopy(STEM) in the New Generation of High-K Gate Dielectrics

扫描透射电子显微镜(STEM)原子序数衬度像(Z-衬度像)具有分辨率高(可直接"观察"到晶体中原子的真实位置)、对化学组成敏感以及图像直观易解释等优点,成为原子尺度研究材料微结构的强有力工具。本文介绍了STEM Z-衬度像成像原理、方法及技术特点,并结合具体的高K栅介质材料(如铪基金属氧化物、稀土金属氧化物和钙钛矿结构外延氧化物薄膜)对STEM在新一代高K栅介质材料研究中的应用进行了评述。目前球差校正STEM Z-衬度的像空间分辨率已达亚埃级,该技术在高K柵介质与半导体之间的界面微结构表征方面具有十分重要的应用。对此,本文亦进行了介绍。

Scanning transmission electron microscopy （STEM） Z-contrast image has some advantages such as high image resolution （directly revealing the real positions of atoms in crystal）, high compositional sensitivity and di- rectly interpretable images, it becomes a powerful tool for investigating the microstructure of materials at atomic scale. In this review, the formation mechanisms, methods and features of the Z-contrast STEM images are intro- duced, and its applications in the new generation of high-k gate dielectrics （e.g., Hf-based metals oxides, rare-earth oxides and epitaxial perovskite oxides） are also reviewed. After aberration-correction the spatial resolution of the Z-contrast STEM images is as high as the sub-A level, this technique is invaluable for characterizing the interfacial structures between high-K gate dielectrics and semiconductors. The related results are also introduced.