MANUFACTURE OF SEMICONDUCTOR DEVICE

PURPOSE:To avoid the punch-through and to decrease the interelement isolation width by a method wherein both a field oxide region and a gate electrode region are simultaneously ion-implanted with impurities. CONSTITUTION:An N-type semiconductor substrate 1 is ion-implanted with P- and N-type impurities so as to form P and N wells 2, 3; a pad oxide film and a nitride film are grown and then the nitride film is selectively removed to form an element isolation region; and then an interelement isolation region of NMOS transistor is ion-implanted with impurities to form a P-type impurity region 14. Successively, a field oxide film 5 is formed to remove the nitride film and the pad oxide film while a gate electrode region, the interelement isolation region and P and N well boundary regions are ion-implanted with impurities to form other P- and N-type impurity regions 7, 9. finally, a gate electrode 11 is formed on the central part of the element formation region through the intermediary of a gate oxide film 10, furthermore, the NMOS and PMOS transistor sides are ion-implanted with N- and P-type impurities in high concentration to form source, drain and a diffused region 12 for writing, thereby completing a CMOS transistor.