栅氧化层及界面电荷对SiC MOSFET阈值电压稳定性的影响  

Effects of Charges in Gate⁃Oxide Layer and Interface on Threshold Voltage Stability of SiC MOSFETs

作　　者：刘兆慧 尉升升 于洪权 尹志鹏 王德君 Liu Zhaohui;Wei Shengsheng;Yu Hongquan;Yin Zhipeng;Wang Dejun(School of Control Science and Engineering,Faculty of Electronic Information and Electrical Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学电子信息与电气工程学部控制科学与工程学院,辽宁大连116024

出　　处：《半导体技术》2023年第6期463-469,共7页Semiconductor Technology

基　　金：国家自然科学基金资助项目(61874017)。

摘　　要：阈值电压不稳定是SiC MOSFET的一个主要问题,而栅氧化层及界面电荷是引起器件阈值电压不稳定的关键因素。结合三角波电压扫描法和中带电压法提取了SiC MOSFET中的栅氧化层陷阱电荷面密度、界面陷阱电荷面密度和可动电荷面密度随应力时间的变化量,总结了三种电荷面密度变化量在不同应力时间下的变化规律,分析了其对器件阈值电压不稳定性的影响,同时推测了长时间偏压作用下SiC MOSFET阈值电压稳定性的劣化机制。测试结果表明,栅氧化层陷阱电荷面密度、界面陷阱电荷面密度和可动电荷面密度在不同偏压温度下随应力时间的变化规律不同,常温应力下器件阈值电压稳定性劣化主要与栅氧化层陷阱电荷有关,而高温下,则主要与界面陷阱电荷有关。Instability of threshold voltage is a key issue of SiC MOSFETs,and charges in gate⁃oxide layer and interface are the main factors that cause the instability of threshold voltage.Variations of gate⁃oxide layer trap charge surface density,interface trap charge surface density and mobile charge surface density with stress time in SiC MOSFETs were extracted by triangular voltage sweep method and midgap voltage method.The variation rules of three kinds of charge surface density variations under different stress time were summarized,and their effects on the instability of threshold voltage were analyzed.At the same time,the degradation mechanism of threshold voltage stability of SiC MOSFETs under long⁃term bias voltage was speculated.The testing results show that the variation rules of gate⁃oxide layer trap charge surface density,interface trap charge surface density and mobile charge surface density vary with stress time at different bias temperatures.The degradation of device threshhold voltage stability under room temperature stress is mainly related to gate⁃oxide layer trap charges,while at high tempera⁃tures,it is mainly related to interface trap charges.

关 键 词：SiC MOSFET 阈值电压不稳定性 栅氧化层陷阱电荷 界面陷阱电荷 可动电荷 

分 类 号：TN386.1[电子电信—物理电子学]