Improving Gate Reliability of 6-In E-Mode GaN-Based MIS-HEMTs by Employing Mixed Oxygen and Fluorine Plasma Treatment

Robust and reliable gate scheme is crucial in developing the enhancement-mode (E-mode) AlGaN/GaN metal-insulator-semiconductor (MIS)-high electron mobility transistors (HEMTs). This work reports on a method of mixed oxygen and fluorine plasma pretreatment combined with selected bi-layer gate dielectrics to improve the performances of partially recessed-gate MIS-HEMTs. The fabricated E-mode HEMTs exhibit significantly boosted threshold voltage of 2.5 V and gate breakdown voltage of 26 V, as well as improved device reliability on 6-in wafer under both bias and temperature stresses. Remarkably reduced $V_{th}$ shift is found even at 250 degrees C high temperature. Furthermore, measurements on gate breakdown lifetime show a ten-year lifetime of the fabricated devices when the gate bias is kept below 13.1 V which demonstrates a promising scheme in fabricating the E-mode HEMT products.

Automated summary

By using a method of mixed oxygen and fluorine plasma pretreatment combined with selected bi-layer gate dielectrics, the performances of partially recessed-gate MIS-HEMTs have been improved, showing significantly boosted threshold voltage and gate breakdown voltage under both bias and temperature stresses. Remarkably reduced threshold voltage shift is observed at high temperature of 250 degrees C.