Semiconductor memory device and manufacture thereof

Abstract

Abstract PURPOSE:To improve the reliability of EEPROM (PROM in which electrical eliminating is possible) is which electrical eliminating and writing is possible by a method wherein a drain region under a tunnel oxide film is kept away by forming the drain region roughly into an L-shape and a stable tunnel oxide film is formed. CONSTITUTION:In EEPROM which is composed of a floating gate electrode 14 formed on a surface of a p type semiconductor substrate 11 with a gate insulating film 13 underneath, a control gate electrode 15, a source region 16 and a drain region 17, the roughly L-shaped drain region 17 to which a drain electrode is connected is kept away from the drain region 17' under a tunnel oxide film 20 which is formed by using properly two kinds of impurities As and P. Here two memory elements are formed symmetically and the drain regions 17, 17' form a T-shape. With above method the stable tunnel oxide film 20 is obtained and the reliability of EEPROM is improved.

Inventors

• 👤 Izumi Tanaka
• 👤 Takashi Yamamoto

Bibliographic Details