POWER SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a power MOS-FET whose ON-resistance is lowered in a superjunction structure and whose built-in diode has inverse recovery characteristics in a soft recovery waveform. SOLUTION: This power MOS-FET has an n-type drift layer 2 inserted on the drain side of its vertical superjunction structure comprising an n-type layer 3 and a p-type resurf layer 4. When a high voltage is applied to the MOS-FET, the n-type layer 3 and the p-type resurf layer 4 are completely depleted, and the impurity concentration of the n-type drift layer 2 is lower than the impurity concentration of the n-type layer 3.