Si基GaN增强型电力电子器件研究

Enhancement-mode GaN-on-Si power electronic devices have become a hot international research topic in recent years, and they are regarded as one of most attractive candidates for next generation of high-efficiency, energy-saving power electronic devices..This work is carried out in collaboration of Institute of Microelectronics of Chinese Academy of Sciences, Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO) of CAS, and Xidian University, based on their capabilities in III-nitride epitaxy, device fabrication and device physics. Selective epitaxy for P- (Al) GaN layer, high-temperature low-damage gate recess, remote-plasma surface nitridation and high temperature LPCVD-SiN passivation are innovatively developed, aiming at the key scientific issues and technical difficulties in the fabrication of enhancement-mode GaN-on-Si power electronic devices, such as large-size GaN-on-Si wafer epitaxy and stress regulation, energy band engineering and regulation of interface states, and the failure mechanism under high-voltage dynamics characterizations. The fabricated enhancement-mode GaN-on-Si power electronic devices are expected to exhibit a threshold voltage more than +3V, an OFF-state breakdown voltage exceeds 900V, and a good gate dielectric/barrier layer interface with density below 1012 cm-2eV-1 at a certain range. .Through implementation of this project, a core research team on GaN-on-Si power devices with significant international influential will be setup, and a number of important and integrated innovations with independent intellectual property rights are expected to achieved in the research field of GaN power electronics.

Si基GaN增强型电力电子器件是近年来国际研究的热点，有望成为下一代高效，节能电力电子的最佳候选之一。本申请项目结合中科院微电子所，中科院苏州纳米所和西安电子科技大学在III族氮化物材料生长、器件工艺和器件物理研究上长期积累的优势，创新采用P-(Al)GaN选区外延，高温栅槽刻蚀，远程等离子体表面氮化和高温LPCVD-SiN介质钝化，突破大尺寸Si基GaN材料外延生长和应力调控，增强型能带工程和界面态调控，以及高场动态特性的失效机理等关键科学问题和技术难点，研制出高性能Si基GaN增强型电力电子器件，实现阈值电压大于 +3 V，击穿电压超过900 V，栅介质/(Al)GaN势垒层界面态在一定范围内低于1012 cm-2eV-1。通过本项目在国内形成一支具有重要国际影响的Si基GaN电力电子器件研究团队，取得若干具有自主知识产权的、从材料到器件的GaN电力电子领域创新成果。

Si基GaN增强型电力电子器件是近年来国际研究和产业化的热点，然而由于自主增强型技术的缺失和表界面态等可靠性瓶颈的制约，限制了我国Si基GaN技术的自主可控和应用推广。本项目结合中科院微电子所，中科院苏州纳米所和西安电子科技大学在III族氮化物材料生长、器件工艺和器件物理研究上长期积累的优势，创新采用栅槽刻蚀和P-(Al)GaN二次外延解决当前P-GaN商业化技术难以兼顾高阈值电压和低导通的挑战，创新设计出无需刻蚀AlGaN的超薄势垒AlGaN(<6nm)/GaN增强型结构，结合高温LPCVD SiNx钝化恢复二维电子气方法，解决了大尺寸Si基GaN栅槽刻蚀的均匀性控制难题，实践了具有自主知识产权的Si基GaN增强型电力电子器件技术路线，获得美国专利授权，并得到了国际同行的高度认可和效仿。项目同时突破了AlGaN上P-GaN的自终止刻蚀工艺，低固定电荷臭氧源原子层沉积Al2O3栅介质，等离子体增强原子层沉积AlN栅介质，Ti/Al/Ti/TiN低温无金欧姆接触等CMOS兼容关键技术。在栅介质和表面钝化工艺中，通过低损伤远程等离子体处理和LPCVD-SiN介质的有效衔接，实现GaN基MIS界面态密度（0.3<Ec-Et<0.6eV）低于4×1011cm-2eV-1。项目组实现了6 英寸Si基GaN薄膜(002)和(102)双晶衍射摇摆曲线半高宽均低于340 arcsec；AlGaN/GaN异质结构二维电子气浓度达到1×1013 cm-2，迁移率达到1940 cm2V-1·s-1，方块电阻347 Ohm/sq，6英寸Si基GaN晶圆厚度均匀性标准偏差为2.7 %，外延片翘曲为30 μm。基于以上创新路线和外延工艺，研制出高性能Si基GaN增强型电力电子器件，实现MIS器件增强型阈值+6V、击穿大于1000V，静态导通电阻0.52mΩ·cm2。开发出适用于MIS器件界面研究的恒定电容深能级瞬态谱技术，提出了一种适用于较宽能级范围界面态分布的U型函数模型，并深入揭示了LPCVD-SiN/GaN近导带界面态的物理起源，为解决GaN基器件界面态问题提供了深刻的理论与实践依据。通过本项目形成了一支具有重要国际影响的Si基GaN电力电子器件研究团队，取得若干具有自主知识产权的、从材料到器件的GaN电力电子领域创新成果。