Investigation of Dependence of Breakdown Voltage on the N-pillar Doping Concentration of Deep Trench Super-Junction Vertical Double Diffused MOSFET

In this paper, the dependence of breakdown voltage on the N-type pillar doping concentration of a silicon-based Deep Trench Super-Junction Vertical Double Diffused MOSFET is carried out using TCAD simulation. The variation of the electric field distribution and impact ionization rate under high drain bias conditions are studied in detail. Also, a peak electric field localization and avalanche initiation within the drift region with varying N-pillar doping concentration are studied. From the analysis, it is clear that the moderately doped Npillar enables uniform depletion and delays the onset of impact ionization, leading to improved breakdown voltage. However, higher doping levels cause partial depletion and premature field crowding away from the drain junction, leading to earlier breakdown. This study highlights the need for optimized N-pillar doping concentration for improved device performance.