High current repetitive avalanche of low voltage trench power MOSFETs

The capability of 20 V trench power MOSFETs to withstand high current repetitive avalanche events has been investigated. Automotive standard 20 V BVdss rated MOSFETs with active area of 21 mm
²
have been successfully subjected with up to 300 million 59 mus duration avalanche events at peak currents up to 135 A whilst held at an average junction temperature of 150degC. The effect of cell pitch on parameter shifts has been investigated by applying avalanche currents up to 200 A (9.5 A/mm
²
). It has been found that reduced cell pitch increases the stability of threshold voltage and on-state resistance whilst suffering from increased drain-source leakage.