Enhanced ESD Reliability of AlGaN/GaN MIS-HEMTs Using a p-Type Oxide Passivation

In this work, we demonstrate for the first time a device-level solution for improved electrostatic discharge (ESD) reliability of AlGaN/GaN MIS-HEMTs using a p-type oxide (AlTiO)-based passivation. Comprehensive ESD tests are conducted, including off-state, semi-on-state, floating gate, and reverse gate–source stress with standard transmission line pulse (TLP), as well as very fast TLP (VF-TLP). In addition, nondestructive ESD pulses are also applied on the drain in the semi-on-state to investigate their impact on device performance. The proposed p-type oxide passivation significantly improves ESD reliability of GaN MIS-HEMTs compared with the conventional SiN passivated GaN MIS-HEMT. The proposed passivation suppresses the channel electric field peak resulting in enhanced off-state ESD breakdown. In the semi-on-state, suppression of the channel electric field peak results in the lowering of the self-heating effect and absence of the thermoelastic strain, thus improving ESD failure. Furthermore, floating gate and gate–source ESD robustness are improved as well. Floating-gate failure is thermally induced, while reverse gate–source failure is attributed to impact ionization. Raman, thermoreflectance, and electroluminescence (EL) characterization are used to find the root cause of improved ESD reliability using AlTiO and to identify the ESD failure mechanisms. Postfailure analysis using FE-SEM is also carried out to identify the material-level implications of ESD stress.