Improvement of P-base contact resistance in power MOSFETs and its impact on avalanche capability

Power MOSFETs may be subjected to voltages above their maximum rated voltage under certain conditions. The maximum current that can be tolerated in such cases is called avalanche capability and is specified and guaranteed in the data sheet. Making it difficult for the parasitic bipolar transistor to operate is an effective way to improve avalanche capability. We have investigated the relationship between the P-base contact resistance, which is one of the factors that cause the parasitic bipolar transistor to operate, and avalanche capability, and have proposed process conditions to reduce the P-base contact resistance from the perspective of the mechanism of occurrence.