VERTICAL POWER MOSFET AND ITS MANUFACTURE

摘要

PROBLEM TO BE SOLVED: To provide a vertical power MOSFET whose gate electrode has superior embeddability, and its manufacturing method. SOLUTION: A groove 10 is formed in such a manner that it penetrates the surface of an n+-type source area 4, the n+-type source area 4, a p-type well area 3 to the midway of an n-type silicon epitaxial layer 2. A gate electrode 6 is embedded in the groove 10 with a gate oxide film 5 formed on the inner circumferential surface of the groove 10 interposed. The groove 10 comprises a first groove 10a which is formed on the side of an n+-type silicon substrate 1 in the depthwise direction of the groove 10, and a second groove 10b which is formed in a manner to penetrate the surface of the n+-type source area 4 to the first groove 10a and of which opening area is larger than the first groove 10a. The first and second grooves 10a and 10b are of trench type.