METHOD OF REDUCING TRAP DENSITY IN OXIDE FILM AND MANUFACTURE OF NONVOLATILE MEMORY CELL USING SAME

摘要

PURPOSE:To provide EEPROM being excellent in endurance characteristics. CONSTITUTION:After the completion of a wafer process including a passivation- forming process, a substrate 1 is carried into a constant temperature bath 20 and a low-temperature heat treatment at about 250 deg.C and for about 50 hours is conducted in N2 atmosphere. This heat treatment reduces the damage of a tunnel oxide film caused by a plasma treatment at the time of forming a passivation film(P-SiN), i.e., a generated trap site and restores the oxide film to the original state to improve endurance characteristics. Further, sand heat treatment is conducted at a comparatively low temperature so that Al wiring does not deteriorate at the heat-treatment temperature either.