碳化硅MOSFET的特性研究

发布时间：2019-05-25 01:20

【摘要】：相比于传统硅(Si)材料,碳化硅(SiC)因其更宽的禁带宽度(3.26eV)、更高的热导率和更高的临界击穿场强,在大功率开关电路和电力系统应用领域得到了广泛的关注。SiC功率器件最突出的性能优势在于其高压、高频和高温工作特性,可以有效地降低电力电子系统的功率损耗。目前,国际上多数行业领先的半导体器件厂商,已在SiC MOSFET器件产品化道路上取得了巨大进展。现阶段,商用SiCMOSFET产品绝大多数为N沟道平面垂直结构,且多家公司已推出了更新的SiCMOSFET产品,其应用前景被寄予了很大希望。与此同时,平面垂直型SiCMOSFET的栅极界面态和由此引发的沟道电子迁移率低的问题,一直是限制SiC MOSFET广泛应用的主要原因。在进行SiC MOSFET工艺设计及结构设计时,前期理论研究多依赖于仿真软件进行物理建模,然而实际的实验结果往往与仿真有较大差距,其主要原因是仿真中未加入准确的SiCMOSFET界面态模型,以及反型层的迁移率模型不准确。因此,针对SiC MOSFET的行业发展和理论研究方面的这些问题,本论文对SiC MOSFET进行了研究和探讨,主要包括以下内容:通过对Cree公司三代SiC MOSFET器件在-160℃C至200℃C温度下进行测试,提取出了每代器件在不同温度下的阈值电压、导通电阻等特征参数。分析比较了三代产品阈值电压、导通电阻随温度的变化趋势,以及不同温度下导通电阻与栅极电压的关系。运用建立物理模型的方法,对三代产品阈值电压、导通电阻的各组成部分与温度的关系进行了比较研究。解释了 SiCMOSFET的阈值电压的温度变化率随产品更新而逐代降低的原因,是栅极Si02/SiC界面存在的界面态密度在逐代的下降。选用Silvaco公司的Atlas TCAD器件仿真软件,对所研究的4H-SiC MOSFET器件进行物理模型的建立。重点研究了 SiC MOSFET器件的迁移率模型的选择及参数设定,以及SiC MOSFET中Si02/SiC界面态模型的参数设定。仿真结果与实验测得的SiC MOSFET的特性随温度的变化较符合。
[Abstract]:Compared with the traditional silicon (Si) material, silicon carbide (SiC) has a wider band gap (3.26eV), higher thermal conductivity and higher critical breakdown field strength. In the field of high power switching circuit and power system application, the most outstanding performance advantage of sic power device is its high voltage, high frequency and high temperature working characteristics, which can effectively reduce the power loss of power electronic system. At present, most of the leading semiconductor device manufacturers in the world have made great progress on the road of SiC MOSFET device production. At present, most of the commercial SiCMOSFET products are N-channel plane vertical structure, and a number of companies have launched updated SiCMOSFET products, its application prospect has been placed in great hope. At the same time, the gate interface state of planar vertical SiCMOSFET and the low channel electron mobility caused by it have always been the main reasons for limiting the wide application of SiCMOSFET. In the process and structure design of SiC MOSFET, most of the previous theoretical research depends on the simulation software for physical modeling. However, the actual experimental results are often quite different from the simulation results. The main reason is that the accurate SiCMOSFET interface state model is not added to the simulation, and the mobility model of the inversion layer is not accurate. Therefore, in view of these problems in the industry development and theoretical research of SiC MOSFET, this paper studies and discusses the SiC MOSFET. The main contents are as follows: by testing the third generation SiC MOSFET devices of Cree Company at the temperature of-160C to 200C, the threshold voltage and on-resistance of each generation of devices at different temperatures are extracted. The variation trend of threshold voltage and on-resistance with temperature, as well as the relationship between on-resistance and gate voltage at different temperatures are analyzed and compared. By using the method of establishing physical model, the relationship between temperature and threshold voltage, on-resistance and temperature of the third generation products is compared and studied. It is explained that the temperature change rate of the threshold voltage of SiCMOSFET decreases generation by generation with the renewal of the product, which is due to the decrease of the interface state density at the gate Si02/SiC interface. The Atlas TCAD device simulation software of Silvaco Company is used to establish the physical model of the 4H-SiC MOSFET device studied. The selection and parameter setting of mobility model of SiC MOSFET devices and the parameter setting of Si02/ sic interface state model in SiC MOSFET are studied in detail. The simulation results are in good agreement with the experimental results of SiC MOSFET with the change of temperature.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN386

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