METHOD OF FORMING ELEMENT ISOLATION FILM AND NONVOLATILE SEMICONDUCTOR MEMORY

摘要

PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory having stable element characteristics, and also a method of forming an STI (Shallow Trench Isolation) insulating film in the memory. SOLUTION: A shallow trench (recess) is formed in an element isolation region of an Si substrate 1, a noncharged trench oxide film 4a having a thickness of about 300Åis deposited on the inner surface of the trench, and then an HDP (High Density Plasma) oxide film 4b having a thickness of about 4,700Åis filled in the inside of the trench oxide film 4a to thereby form an STI film 4 for element isolation. As a result, since the underside of the STI film 4 (trench oxide film 4a) is not charged, the substrate undergoes no damage and a reliable insulating film is obtained. The reliable insulating film is optimum as the insulating film for a nonvolatile semiconductor memory having a floating gate FG. COPYRIGHT: (C)2008,JPO&INPIT