JPS649638A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To secure a broad active region and to isolate elements sufficiently without complicated steps, by adopting the steps, by which element isolating insulation films are formed on a semiconductor substrate, and thereafter etching and removing the upper parts of the films. CONSTITUTION:The upper surface parts of a silicon oxide film 3 and an interelement dielectric isolation film 9 on the entire surface of a memory array part are removed by etching. Thus, a thin element isolating film 9a is obtained. In this way, the thickness of the element isolating insulation film 9a at the memory array part (b) becomes thinner than the thickness of the interelement dielectric isolating films 9, which remain in a peripheral circuit part (a). When the thickness of the film is decreased, the tip part of each bird's beak B is removed. Therefore, an initial isolating length lB between the elements at the interelement dielectric isolation film 9 is shortened to an isolation length lbetween the elements at the interelement dielectric isolating film 9a after the etching. an active region C at the memory array part is expanded.