Analytic Model of Specific ON-State Resistance for Superjunction MOSFETs With an Oxide Pillar

An analytical model for superjunction (SJ) MOSFETs having an oxide pillar between the n-pillar and the p-pillar is developed. Owing to the low permittivity of the oxide, a high electric field is sustained across the oxide. This reduces the parasitic depletion widthwithin the n-pillar, thus improving the current conducting path. The advantage of this structure is particularly visible as the cell pitch is scaled down and the pillows become narrower. The use of an oxide pillar leads to 30% reduction in the specific ON-state resistance when compared to a conventional SJ for a 2-mu m cell pitch. The analytical model shows a good agreement with the simulation results.