Analysis of TID Effects on the Threshold Voltage and Breakdown Voltage of 100-V Split-Gate Trench VDMOS

This article investigates the impact of total ionizing dose (TID) on 100-V split-gate trench vertical double-diffused MOSFETs (SGT VDMOS). The experimental results for both ON-state and OFF-state irradiation are explored, focusing on the shift in threshold voltage (
${V}_{\text {th}}$
) and breakdown voltage (BV). The physical mechanisms responsible for BV shifts after ON-state irradiation and OFF-state irradiation are analyzed and verified using Sentaurus TCAD with two distinct positive oxide trapped charge (
${N}_{{\text {ot}}}$
) models. The analysis reveals that BV shifts are attributable to the redistribution of the electric field due to positive oxide trapped charges induced by TID, which suppress depletion in the drift region. To mitigate this issue, a radiation-hardened SGT VDMOS with double p-pillars is proposed. The introduction of double p-pillars significantly improves TID tolerance on BV by facilitating an enhanced depletion effect. The effectiveness of this proposed solution has been analyzed in this study.