ISOLATING METHOD OF SEMICONDUCTOR DEVICES

摘要

PURPOSE: An isolating method of semiconductor substrate is provided to restrain a bird's bean punch-through by using a polysilicon spacer. CONSTITUTION: The method comprises the steps of forming a first oxide(102) and a nitride layer(104) on a silicon substrate(100); defining an active region by etching the nitride layer(104); under-cutting the first oxide(102) formed at edge portion of the nitride pattern using wet-etching; forming a second oxide(106) and a Si-N-O film(107) on the resultant structure; forming a polysilicon spacer(108) at both sidewalls of the nitride pattern; growing an isolating oxide(110) by thermal oxidation; and removing the nitride pattern and the first oxide(102). In the oxidation process, the oxygen ions penetrated in the lower part of the polysilicon spacer(108) are restrained by the Si-N-O film(107), thereby preventing the bird's beak punch-through.