SiC/SiO2界面的原子分辨率三维重构

SiC/SiO₂界面的原子分辨率三维重构

刘培植^1，2*，许并社^1，2，郭俊杰^1，2*

（太原理工大学1. 新材料工程研究中心，2. 教育部新材料界面与工程重点实验室，山西太原，030024)

摘 要：碳化硅（SiC）作为一种新型材料被广泛应用于高功率半导体器件中。目前的SiC基金属氧化物半导体场效应晶体管器件存在的主要问题是沟道电子迁移率低。SiC/SiO₂界面处的过渡层被认为是造成沟道电子迁移率低的主要原因，但是该过渡层的原子结构尚不清楚。本文利用球差矫正扫描透射电子显微镜深入研究了SiC/SiO₂的界面。以变聚焦序列技术得到了界面过渡层不同深度的原子分辨率断层扫描图像，用变聚焦序列图像重构了界面的原子分辨率三维结构。精确的界面原子结构表明SiC/SiO₂ 界面处的过渡区是由于邻晶界面上台阶突起和微刻面构成的。它是界面原子尺度的粗糙度的反映。邻晶界面上的台阶突起和微刻面增加了电子在界面传输过程中的散射几率，造成了沟道电子迁移率过低。

关键词：扫描透射显微镜；变聚焦图像序列；三维重构；界面；沟道电子迁移率

中图分类号：TN304.2⁺4；O485；O763；TG115.21⁺5.3   文献标识码：A   doi:10.3969/j.issn.1000-6281.2015.05.003

Atomic resolution 3D reconstruction of SiC/SiO₂ interface

LIU Pei-zhi^{1, 2*}，XU Bing-she^{1, 2}，GUO Jun-jie^{1, 2*}

(1.esearch Center of Advanced Materials Science and Technology，Taiyuan University of Technology，Taiyuan  Shanxi  030024；2. Key Laboratory of Interface Science and Engineering，Advanced Materials of Ministry of Education，Taiyuan University of Technology，Taiyuan  Shanxi  030024，China）

Abstract: Silicon carbide (SiC) is widely used in high power electronics as a substitute of silicon. The key problem of SiC based metal-oxide-semiconductor field effect transistors (MOSFET) is the relatively low channel electron mobility, and the transition layer of SiC/SiO₂ interface is considered to be the main cause for the reduced electron mobility. However, the atomic structure of the transition layer is still unclear. In this paper, the transition layer was investigated with a 5^th order spherical aberration corrected scanning transmission electron microscope. Depth sectioning images of SiC/SiO₂ interface were obtained with the through-focal series technique, and an atomic resolution 3D structure of the interface was reconstructed with the through-focal series images. The clear 3D interface structure suggests that the interface has an atomic scale roughness, and the transition layer is a contrast of the roughness. The kinks, steps and microfacets increase the scattering probability of channel electrons, resulting in reducing the channel mobility of the MOSFET devices.

Keywords: STEM；through-focal series；3D reconstruction；interface；channel electron mobility

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