| 摘要 |
PURPOSE:To improve the reliability of a semiconductor device under radiation, by detecting the amount of change in threshold value of an MISFET due to the radiation, computing the correcting amount based on the detected value, controlling the back gate bias of the FET using said correcting amount, thereby correcting the fluctuation of the threshold value. CONSTITUTION:An N<-> type layer 4 is epitaxially grown on a P<-> type Si substrate 3. In this layer, a regular C-MISFET element B and a dummy C-MISFET element A for detecting the shifting amount of a threshold voltage Vth are formed. When gamma rays are projected on a semiconductor device and the Vth of the FET is fluctuated, the fluctuated value is measured by a detecting circuit 1 and an input voltage Vin is controlled. The fluctuating amount of the Vthp of the PMISFET and the fluctuating amount of the Vthn of the NMISFET are analyzed by a CPU 2. The correcting amount is determined based on the characteristic curve and the correcting curve, which are measured beforehand, and the back gate bias of the C-MISFET is controlled.
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