VERTICAL FIELD EFFECT TRANSISTOR

摘要

PROBLEM TO BE SOLVED: To provide vertical MOS where BVDS is improved without increasing on-resistance with a simple structure. SOLUTION: A plurality of unit cells 10 formed on an N-type epitaxial layer 12 which is deposited on an N+semiconductor substrate 11 and whose impurity concentration is lower than the semiconductor substrate 11 are regularly arranged. A trench 13 whose depth is Xa and whose width is (h) is formed around the unit cell 10. A gate electrode 25 is buried in the trench 13 through a gate oxide film 24 whose film thickness is tox. The unit cell 10 is provided with a P-type base region 21 whose depth is Xb, a source region 22, a high concentration P-type region which is formed in a center part and whose depth is Xc and the gate insulating film 24 formed in a face opposite to the trench 13. Xb