4H-SiC MESFET的反应离子刻蚀和牺牲氧化工艺研究

Reactive Ion Etching and Sacrificial Oxidation Processes in the Fabrication of 4H-SiC MESFETs

对于栅挖槽的4H-SiCMESFET,栅肖特基接触的界面经过反应离子刻蚀,界面特性对于肖特基特性和器件性能至关重要。反应离子刻蚀的SiC表面平滑度不是很好,刻蚀损伤严重。选择合适的RIE刻蚀条件减小刻蚀对半导体表面的损伤;利用牺牲氧化改善刻蚀后的表面形貌,进一步减小表面的刻蚀损伤。工艺优化后栅的肖特基特性有了明显改善,理想因子接近于1。制成的4H-SiCMESFET直流夹断特性良好,饱和电流密度达到350mAmm。

For gate recessed 4H-SiC MESFETs, the Schottky gate is formed on a plasma etched surface. The quality of the surface is crucial to the Schottky contact properties and device performance. In this study sacrificial oxidation is used as a post-etch treatment to reduce surface roughness and etch damage. Etch damage is also reduced by using proper RIE settings. Optimized etch condition and surface treatment result in improved Schottky-contact characteristics and excellent current-voltage characteristics of the 4H-SiC MESFETs.