Off-state avalanche-breakdown-induced on-resistance degradation in SGO–NLDMOS

In this paper, on-resistance (Ron) degradation induced by off-state avalanche breakdown in a 40 V LDMOS with step-shaped gate oxide (SGO–LDMOS) is investigated. Ron unexpectedly decreases at the beginning of stress, which is different from the phenomenon described in works on LDMOS with uniform gate oxide (UGO–LDMOS). Based on the experiment data and TCAD simulation results, two degradation mechanisms are proposed. That is the generation of positive oxide-trapped charges at the bird’s beak region near source and formation of interface state at the bird’s beak region near source and drain respectively.

► Degradation induced by off-state avalanche breakdown in SGO–LDMOS is investigated.
► The anomalous phenomenon of on-resistance Ron degradation is disclosed.
► Based on the experiment and TCAD simulation, two degradation mechanisms are proposed.