SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

摘要

PURPOSE:To prevent the gate insulating film of an MISFET from electrostatically damaging by providing the first conductive type third semiconductor region having higher impurity density than the first semiconductor region in contact with the second semiconductor region. CONSTITUTION:A reverse conductive type semiconductor region 21 or 26 is formed on the main surface of the first semiconductor region made of n<--> type semiconductor substrate 1 or p<--> type well region 2, the same conductive type semiconductor region 22 or 27 having higher impurity density than the substrate 1 or the region 2 is formed in contact with the region 21 or 26 to form a diode 7 or 8. Carrier to be injected to the region 21 or 26 by a positive or negative surge voltage is preferably absorbed by the region 22 or 27. Thus, the surge voltage can be rapidly reduced to preferably prevent the gate insulating film of an MISFET from electrostatically damaging.