Semiconductor device with element isolation using impurity-doped insulator and oxynitride film

摘要

In a trench (2), an oxynitride film (31ON1) and a silicon oxide film (31O1) are positioned between a doped silicon oxide film (31D) and a substrate (1), and a silicon oxide film (31O2) is positioned closer to the entrance of the trench (2) than the doped silicon oxide film (31D). The oxynitride film (31ON1) is formed by a nitridation process utilizing the silicon oxide film (31O1). The vicinity of the entrance of the trench (2) is occupied by the silicon oxide films (31O1, 31O2) and the oxynitride film (31ON1).