HIGH-FREQUENCY SEMICONDUCTOR DEVICE

摘要

PURPOSE:To prevent the lowering of the withstanding voltage of a high-frequency semiconductor device by forming a diode for protecting a gate oxide film in the chip of an MOS capacitor for matching input impedance. CONSTITUTION:Diodes D4, D5 for protecting a gate oxide film in an MOS field- effect transistor are shaped in the chip of an MOS capacitor for matching input impedance. The MOS capacito for matching input impedance is constituted by an N type substrate 13 for the capacitor, an insulating film 14 and an Al electrode 15. The diodes D4, D5 for protecting the gate oxide film are formed by the N type substrate 13 for the capacitor, a P type diffusion layer 16 and an N type diffusion layer 17.