超高压4H-SiC GTO晶闸管结终端技术研究

The 4H-silicon carbide gate turn-off thyristor (4H-SiC GTO) is of specific interest because of its great advantages over silicon counterparts, such as high-temperature, high-voltage, and high-current applications. However, the breakdown voltage (BV), as a criticial characteristic of 4H-SiC GTO, is usually much smaller than that of the ideal parallel-plane junction, and which is mainly due to the electric field crowding at the edge of 4H-SiC GTO. Therefore, a simple and effective edge termination structure is urgently required for 4H-SiC GTO devices. In this work, properties and functions of junction termination extension structures (JTE) based on etching and ion-implantation will be investigated to enhance the avalanche BV, and analytical model for the surface potential and electrical field distributions will be developed by solving 2-D Poisson’s equation. Next, two edge termination methods, referred to as simple multistep etched JTE and implanted multiple-zone JTE, are presented for 4H-SiC GTO, and both of the two techniques can form high efficient edge termination with large process window and small cost. Meanwhile, the quality and passivation technique of SiO2/SiC are investigated to reduce the impact of interface charge and fixed charge in passivation layer on BV characteristic. Finally, the ultra-high voltage 4H-SiC GTO will be fabricated with the proposed edge termination. This work will provide the necessary scientific basis and technical proposal for the edge termination design of SiC power device, and it has great scientific significance and application value.

在SiC高压功率器件中，门极可关断晶闸管（GTO）由于具有高阻断电压、大电流、低正向导通压降以及耐高温等优点而受到广泛关注。而阻断电压作为GTO的一项关键性能指标，由于受到电场集聚效应的限制，器件往往会在远小于理想阻断电压时就发生了击穿，因而设计简易高效的结终端是研制超高压GTO器件的难点所在。基于此，本项目拟围绕结终端扩展(JTE)技术，深入研究终端区域电场调制机理，并通过数值模拟揭示结构参数对终端区域电场的调控机制；其次，创新性地提出了简易多级刻蚀台阶JTE和注入多区JTE方案，两种方案均能极大地提升结终端的效率、增大工艺容限和降低工艺制备的复杂度，同时重点研究SiO2/SiC界面特性和钝化技术以减小界面电荷和介质中的固定电荷对器件耐压特性的影响，并最终完成超高压SiC GTO器件制备。本项目为碳化硅高压功率器件结终端设计提供理论依据和技术方案，具有重要的科学意义和应用价值。

SiC门极可关断晶闸管（GTO）具有高阻断电压、大电流、低正向导通压降以及耐高温等优点而受到广泛关注。其中阻断电压作为GTO的一项关键性能指标，由于受到电场集聚效应的限制，器件往往会在远小于理想阻断电压时就发生了击穿。而传统场限环/结终端扩展结构端受限于效率低、尺寸大、鲁棒性差等问题并不能满足10kV等级超高压SiC GTO器件的应用需求，因此探索高效结终端技术是实现超高压SiC功率器件（>10kV）的关键所在。.基于此，课题围绕结终端扩展(JTE)技术，首先深入研究终端区域电场调制机理，并通过数值模拟揭示结构参数对终端区域电场的调控机制，为SiC GTO高压器件结终端结构设计提供了理论指导；其次，开展了刻蚀型JTE和注入型JTE结终端结构设计和参数优化，给出了SiC GTO高压器件结终端结构设计方案；最后，完成了SiC GTO高压器件结构设计、工艺流程设计和关键工艺开发，并最终完成超高压SiC GTO器件制备。.通过测试验证得到，基于90μm/2×1014cm-3漂移区参数的SiC GTO器件阻断电压为11.9kV，结终端效率达到92%，满足10kV高阻断电压的指标需求，验证了该结终端技术的有效性和可行性，本项目为碳化硅高压功率器件结终端设计提供理论依据和技术方案，具有重要的科学意义和应用价值。