A Novel Atomic-Level Post-Etch-Surface-Reinforcement Process for High-Performance -GaN Gate HEMTs Fabrication.

A novel atomic-level post-etch-surface-reinforcement (PESR) process is developed to recover the -GaN etching induced damage region for high performance -GaN gate HEMTs fabrication. This process is composed of a self-limited surface modification step with O plasma, following by an oxide removal step with BCl plasma. With PESR process, the AlGaN surface morphology after -GaN etching was comparable to the as-epitaxial level by AFM characterization, and the AlGaN lattice crystallization was also recovered which was measured in a confocal Raman system. The electrical measurement further confirmed the significant improvement of AlGaN surface quality, with one-order of magnitude lower surface leakage in a metal-semiconductor (MS) Schottky-diode and 6 times lower interface density of states () in a MIS C-V characterization. The XPS analysis of AlO/AlGaN showed that the -GaN etching induced F-byproduct and Ga-oxide was well removed and suppressed by PESR process. Finally, the developed PESR process was successfully integrated in -GaN gate HEMTs fabrication, and the device performance was significantly enhanced with ~20% lower of on-resistance and ~25% less of current collapse at V bias of 40 V, showing great potential of leverage -GaN gate HEMTs reliability.