Gate trench dry etching technology with damage blocking layer for GaN HEMT devices

In this work, the etching damage blocking layer by adding C 2 H 4 to a conventional recipe was investigated during gate trench etching fabrication and the etching damage was compared between the etched samples. Based on the Hall-effect measurement results, it shows that due to the nano-scale Carbon -Hydrogen polymer was formed as dynamic protective layer, which has the blocking effect on the heavy ions bombardment to the AlGaN surface, a high electron mobility of 4856 cm 2 /Vs is achieved on the BCl 3 /Cl 2 /C 2 H 4 etching sample. The atomic force microscopy (AFM) scan results indicate that the BCl 3 /Cl 2 /C 2 H 4 etching method obtains an etched AlGaN surface with lower roughness than BCl 3 /Cl 2 etching, and Transmission Electron Microscope (TEM)/Energy Dispersive Spectrum (EDS) chemical element analysis reveals that adding C 2 H 4 promotes the volatility of Ga etching products, which leads to a smoother etched surface.