SiC槽栅型功率器件可靠性研究与器件结构设计

The main thrusts of the application are to understand the reliability physics of the SiC trench gate power devices and to design novel trench gate device structures. For the SiC trench MOSFETs, characterization platform will be built to investigate the application-related reliability issues, such as short-circuit capability and avalanche ruggedness. For reducing the gate oxide field, SiC trench MOSFET have integrated shielding structures. The project will compare and build the reliability physics for the SiC trench MOSFET, and provide guidance for further developing the devices. For the SiC trench IGBT, there is no feasible solution on how to implement the device. As the SiC trench IGBT is a bipolar device, the gate shielding structure developed in SiC trench MSOFET cannot be transferred to SiC trench IGBT, since it would severely degrade the device conduction characteristics. The project will explore novel floating-type shielding structure for the SiC trench IGBT, aiming at effective gate protection without degrading the conduction characteristics. In this application, the application will exploit the minority carrier injection in the SiC trench IGBT to eliminate the dynamic degradation induced by the floating shielding structure. Thus, a trench IGBT structure suitable for SiC would be established.

本申请项目将对SiC槽栅型功率器件的可靠性与新型结构设计进行研究。对于SiC槽栅MOSFET，本申请项目将搭建测试平台，对器件的短路安全能力、雪崩耐量等应用过程中的可靠性问题进行测试分析。SiC槽栅MOSFET中都集成了栅氧电场屏蔽层以保护栅氧。本申请项目将建立具有不同屏蔽技术的SiC槽栅MOSFET结构的退化机制，指明器件技术优化方案。对于面向高压应用的SiC槽栅IGBT，目前业界还没有可行的技术方案。由于SiC槽栅IGBT是一个双极性器件，针对SiC槽栅MOSFET所开发的屏蔽技术将使得SiC槽栅IGBT的正向导通特性退化。申请人将探索新型基于浮空屏蔽层的技术，在抑制栅氧高电场的同时，保持SiC槽栅IGBT的优异的正向导通特性。在本申请项目中，申请人将创新性地利用SiC槽栅IGBT自身的少子注入效应，来消除浮空屏蔽层所带来的动态退化现象，最终获得适用于SiC的槽栅IGBT结构。

随着大量对电能效率与系统重量有着苛刻要求的新型应用的涌现，以SiC为代表的宽禁带半导体功率电子器件由于其材料禁带宽度大、临界击穿电场高、耐高温等优点,受到广泛的关注和应用。功率半导体电子器件的性能决定了电子设备的能源使用效率，性能等特点。本项目从器件设计、可靠性探究、功能性拓展等方面探究功率电子器件发展空间。在器件设计方面，成功设计出新型SiC IGBT，具有p型屏蔽层保护栅氧免受高电场的破坏。在可靠性探究方面，基于SiC结势垒肖特基二极管，研究分析了承受耐压的pn结的p型区与接地电极之间电极接触类型对器件特性的影响，研究发现肖特基接触电极接触类型，会导致JBS二极管的动态正向压降产生退化。在功能性拓展方面，设计了具有优异反向恢复功能的新型功率器件MOSFET，从而降低系统成本，降低系统中的寄生电感，减小系统体积，有利于电子产品向便携性发展。