| 摘要 |
PURPOSE:To stabilize the circuit operation with respect to the projection of radiation, by covering a thick oxide film around an MOSFET by a first metal layer, and making the potential of said metal layer to be the lowest potential. CONSTITUTION:On a P type silicon substrate, an N type source and drain regions 1, a thick oxide film 4 and gates 2 are provided. Thus an MOSFET is formed. The outer part of the MOSFET is covered by a metal layer 5 through an insulating film (not shown). The metal layer 5 is connected to a power source for the lowest potential of an integrated circuit device including the MOSFET. By the connection to the lowest potential (e.g., ground potential), an electric field is not applied to a thick oxide film 3. Even if radiation is projected on the device, increase in hole density in the vicinity of the boundary with silicon in the thick oxide film is small. The decrease in a part VT2 of the thick oxide film 3 can be made small. Even is VT2 hasd been decreased, an inverted layer is not formed beneath the thick oxide film 3 as long as the value of VT2 is positive. |
