JP2663668B

PURPOSE:To enhance an overall gate in breakdown strength by a method wherein an oxide film where a window is selectively provided to form a diffusion layer in which crystal defect is liable to occur is formed thicker than the gate oxide film of a unit MOSFET. CONSTITUTION:A diffusion layer 2 whose conductivity type is opposite to that of a substrate 1 is provided so as to enable a gate bonding region 10 to be potentially connected to a unit MOSFET 4. The diffusion layer 2 is potentially connected to a source 9. A polysilicon gate 6 and a gate aluminum electrode 8 are arranged as insulated from the diffusion layer 2 by an oxide film thicker than the gate oxide film 5 of the unit MOSFET 4. ln this case, a thick oxide film is provided to a part where a window is partially provided when the diffusion layer 2 is formed, so that a gate can be improved in breakdown strength.