New Insight Into Total-Ionizing-Dose Effect-Induced Breakdown Voltage Degradation for SOI LDMOS: Irradiation Charge Field Modulation

In this article, the concept of irradiation charge field (
${E}_{\text {rc}}$
) is proposed to provide a new insight into total-ionizing-dose (TID) effect-induced breakdown voltage (BV) degradation for high-voltage silicon-on-insulator (SOI) lateral double-diffused metal–oxide-silicon (LDMOS). A unified explanation on TID-induced BV degradation is given that
${E}_{\text {rc}}$
exerts modulation on net electric field, changing the relationship between lateral BV (BVL) and vertical BV (BVV).
${E}_{\text {rc}}$
would weaken electric field at silicon side of silicon/buried oxide interface and enhance that at oxide side, resulting in BVV increasing monotonously.
${E}_{\text {rc}}$
would also weaken surface electric field at drain side and enhance that at source side, resulting in BVL changing with two potential trends: monotonic descent and nonmonotonic descent, corresponding to different initial surface breakdown points. Eventual BV degradation is determined by the combined result of BVV and BVL changing. Based on the new insight, a radiation hardening design strategy is proposed. Nonuniform initial surface electric field distribution with single drain peak is pursued, breaking the conventional optimization principle. Nonmonotonic descent of BV is achieved to enhance TID tolerance and verified by the developed 80-V SOI LDMOS with the proposed radiation hardening strategy.