4H-SiC外延形貌缺陷对MOSFET电学特性影响研究

doi:10.16553/j.cnki.issn1000-985x.2025.0223

摘要/Abstract

摘要： 4H-SiC金属氧化物半导体场效应晶体管（MOSFET）凭借高击穿电压、快速开关、低损耗等优异性能，成为最具发展潜力的半导体器件之一。然而外延过程形成的形貌缺陷会影响MOSFET的良率和可靠性。本文研究了三种形貌缺陷对6.5 kV MOSFET电学特性的影响。结果表明，三角形缺陷会导致器件早期击穿，反向击穿电压不大于3 V，缺陷位于有源区还会导致栅控失效。类三角形缺陷和直线型缺陷对器件的击穿电压无明显影响，但类三角形缺陷导致器件的导通电阻增大了4.56%。与直线型缺陷相比，尽管类三角形缺陷的带隙收缩较小，但其形貌区域存在更显著的应力集中，且堆垛层错面积为直线型缺陷的5倍，从而导致器件导通电阻增大。此外，类三角形缺陷和直线型缺陷均在导电原子力显微镜施加负压时漏电，尽管两者未引起器件静态特性明显变化，但仍不利于器件的长期可靠性。

关键词: 4H-SiC; 金属氧化物半导体场效应晶体管; 外延形貌缺陷; 电学特性; 击穿电压; 导通电阻

Abstract: 4H-SiC metal-oxide-semiconductor field-effect transistor （MOSFET） has become one of the most promising semiconductor devices due to their excellent properties such as high breakdown voltage， fast switching， and low loss. However， the yield and reliability of MOSFET can be degraded by morphological defects formed during the epitaxial process. In this study， the influence of three types of morphological defects on the electrical characteristics of 6.5 kV MOSFET was investigated. The results show that triangle defects can lead to early breakdown of the device， with a reverse breakdown voltage not exceeding 3 V. Furthermore， the presence of these defects in the active region also induces gate control failure. In contrast， triangle-like defects and linear defects have no significant impact on the breakdown voltage of the device， but the on-resistance of device with the triangle-like defect increases by 4.56%. Although triangle-like defects exhibit smaller band-gap shrinkage compared to linear defects， they introduce higher localized stress in their morphology and have a stacking fault area five times larger than that of linear defects， resulting in increased on-resistance of the device. In addition， both triangle-like defects and linear defects exhibit leakage current when a negative voltage was applied by the conductive atomic force microscope. Although neither type of defect caused significant changes in the static characteristics of the device， this behavior remains detrimental to long-term reliability.

Key words: 4H-SiC; MOSFET; epitaxial morphological defect; electrical characteristic; breakdown voltage; on-resistance

中图分类号:

王品, 王静, 刘德财, 张文婷, 于乐, 李哲洋. 4H-SiC外延形貌缺陷对MOSFET电学特性影响研究[J]. 人工晶体学报, 2026, 55(3): 387-394.

WANG Pin, WANG Jing, LIU Decai, ZHANG Wenting, YU Le, LI Zheyang. Influence of 4H-SiC Epitaxial Morphological Defects on the Electrical Characteristics of MOSFET[J]. Journal of Synthetic Crystals, 2026, 55(3): 387-394.

图/表 8

图1 形貌缺陷的散射、可见-紫外光致发光和形貌通道图

Fig.1 Scatter， Vis-PL， and topography channels images of morphological defects

图2 含三角形缺陷MOSFET的OM图像及性能图。（a）三角形缺陷位于有源区OM图；（b）三角形缺陷位于终端区OM图；（c）器件反向I-V特性；（d）体二极管的I-V特性

Fig.2 Optical microscopy （OM） images and characteristics of MOSFETs with triangle defects. （a） OM image of the triangle defect located in the active region；（b） OM image of the triangle defect in the termination region；（c） reverse I-V characteristics of devices；（d） I-V characteristics of the internal body diode

图3 含类三角形缺陷和直线型缺陷的MOSFET性能对比图。（a）器件反向特性；（b）类三角形缺陷/无缺陷器件的转移特性对比；（c）直线型缺陷/无缺陷器件的转移特性对比；（d）器件导通电阻

Fig.3 Characteristics comparison of MOSFETs with triangle-like defects and linear defects. （a） Reverse I-V characteristics for devices；（b） transfer characteristics for devices with/without triangle-like defects；（c） transfer characteristics for devices with/without linear defects；（d） on-state resistance （Ron） of devices

图4 类三角形缺陷和直线型缺陷的OM图和高度剖面图

Fig.4 OM images and height profiles of the triangle-like defect and linear defect

图5 类三角形缺陷（a）和直线型缺陷（b）的高度和漏电流叠加三维图

Fig.5 Three-dimensional overlay plots of height and leakage current of the triangle-like defect （a） and the linear defect （b）

图6 类三角形缺陷和直线型缺陷的PL图

Fig.6 PL spectra of the triangle-like defect and the linear defect

图7 类三角形缺陷和直线型缺陷的拉曼光谱

Fig.7 Raman spectra of the triangle-like defect and the linear defect

图8 类三角形缺陷（a）和直线型缺陷（b）的OM图和拉曼面扫图

Fig.8 OM images and Raman mapping images of the triangle-like defect （a） and the linear defect （b）

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