Non-voratile semiconductor memory device

Abstract

Abstract PURPOSE:To improve the memory retaining property with a charge diffusion barrier film in the second gate insulating film for charge storage provided on a gate insulating film presenting a tunnel phenomenon of the charge. CONSTITUTION:An Si4N3 film 51 is piled on an extremely thin SiO2 film 4 and immersed in a specified mixed solution of H2SO4 and H2O2 to form an extremely thin SiO2 film 42. By the same procedure, an SiO2 film 42 serving as charge diffusion barrier in the second gate insulating film comprising Si3N4 films 51-53. With this structure, a relatively large positive voltage is given the gate electrode 6 to trap electrons in the Si3N4 film with implantation of ions from the substrate 1. As the electron diffusion in the Si3N4 film is made between the centers of trapping in the film, the film makes possible tunneling of the electrons trapped, but provides a barrier after the removal of voltage. Therefore, after the implantation of charge, there is little change in the threshold voltage thereby ensuring an excellent memory retaining property.

Inventors

• 👤 Norio Endo
• 👤 Shigeru Morita

Bibliographic Details