Nonvolatile semiconductor memory storage

Abstract

Abstract PURPOSE:To reduce the size of an element while maintaining excellent characteristics, and to increase the degree of integration by each disposing first and second control gates so as to be opposed to opposite side walls of a recessed section through an insulating film and arranging a floating gate so that it is opposed to the bottom of the recessed section through the insulating film while it is opposed to the control gates through the insulating film. CONSTITUTION:The recessed section 31 is formed to a p type Si substrate 21 through selective etching, a first gate oxide film 241 is formed on the whole surface through thermal oxidation, a polycrystalline silicon film 25 is deposited, and a CVD oxide film 32 is deposited so as to bury the recessed section 31. An etching-resisting mask 33 is formed, and the polycrystalline silicon film 25 is etched to form the first control gate 251 and the second control gate 252. The exposed section of the first gate oxide film 241 is removed through etching once, a second gate oxide film 242 is formed on the surfaces of the substrate 21 and the control gates 251, 252 through thermal oxidation, while the polycrystalline silicon film is flattened and patterned, and the floating gate 26 is formed.

Inventors

• 👤 Masashi Wada
• 👤 和田　正志

Bibliographic Details