Effect of Split-Gate Structure in SiC MOSFET on Single-Event Gate Oxide Damage

Abstract

This study designed a type of silicon carbide (SiC) split-gate MOSFETs (SG-MOSFETs) to evaluate the effect of SG structure on single-event gate oxide damage under heavy-ion irradiation. Comparisons with conventional MOSFETs (C-MOSFETs) by krypton (84Kr+18) ion irradiation experiments showed that SG-MOSFETs exhibited no significant improvement in single-event leakage current (SELC) degradation. However, following irradiation at a drain bias of 100 V, the gate bias at which the SG-MOSFET reached the current limit during postirradiation gate stress (PIGS) tests increased by approximately 60%, indicating SG-MOSFETs enhanced their irradiation reliability at low drain bias. In C-MOSFETs, the damage was located above the center of the JFET region within the active region. In contrast, in SG-MOSFETs, the damage was observed at the corner of the polysilicon gate in the main junction region. This shift in the damage location suggests that the SG structure moves the most sensitive point from the center of the JFET region to other areas. However, structure deviations during the manufacturing of the SG may introduce new sensitivities. Therefore, further design optimization is needed to improve irradiation survivability at higher drain biases.