| 摘要 |
PROBLEM TO BE SOLVED: To mitigate current leakage, to prevent deterioration of main withstand voltage, and to stabilize characteristics of gate oxide film withstand voltage, in a vertical MOSFET having a trench gate. SOLUTION: An n<+> semiconductor substrate 1 comprising As and employing a silicon wafer as a matrix, contains oxygen having a concentration ranging from 12E17 atoms/cm3 or more to 20E17 atoms/cm3 or less. An n-type first epitaxial growth layer 2 and a p-type diffusion layer 3 are consecutively formed on a second main surface 1S2 of the semiconductor substrate 1. The thickness of an epitaxial growth layer 10 is set to be 20μm or less. A trench 6 is formed extending from the surface of the diffusion layer 3 to the inner portion of the first epitaxial growth layer 2. Further, a gate oxide film 5 is formed on a bottom surface 6B and a wall surface 6W of the trench 6, followed by filling the inside of the trench 6 with a conductive layer 11. Subsequently, an n-type source layer 4 is formed at a corner portion of the trench 6. Thus, a device is completed after forming a predetermined electrode, and the like.
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