Forming field oxide insulating film using LOCOS process for semiconductor device mfr.

摘要

After forming a mashing film pattern, an oxide film is locally formed on a parent surface region of the semiconductor substrate by starting the oxidation process, using the mashing pattern. The oxide film is removed for etching a preset region of the substrate surface. Thus an undercut is formed in region located under a side wall of the masking pattern. On the undercut is formed an oxidation preventing film, and an element insulating oxide film is formed on an exposed section of the semiconductor substrate during etching of the substrate preset region.