| 摘要 |
A nonvolatile semiconductor memory device comprises of a channel-forming region of a semiconductor on which a tunnel film, a nitride film, and a top oxide film are laminated between a gate electrode in order from the lower layer. The thickness T of the tunnel film is within a range where charges in the substrate directly tunnel through the tunnel film and is 2.2 (preferably 3.4) nm or more. In this case, the thickness of the top oxide film is set up to thinner than the conventional thickness in order to make the amount of transition of carriers passing through the top oxide equal to or more than the amounts of transition of carriers passing through the tunnel film in a read operation. Preferably, the top oxide film is thinner than the tunnel film. Further, the nitride film has a higher silicon content than the stoichiometric ratio thereof (Si:N=3:4).
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