Patent attributes
A semiconductor memory device includes a semiconductor substrate, a gate insulating film on the semiconductor substrate, a gate electrode on the gate insulating film, control insulating films formed on both side faces in a gate length direction of the gate electrode, charge storage layers formed on both the side faces via the control insulating films, a tunnel insulating film formed between the charge storage layers and the semiconductor substrate, and source/drain regions between which the gate electrode and the charge storage layers are interposed, and which are formed in a surface of the semiconductor substrate. Preferably, fixed information is stored depending on presence/absence of an impurity diffusion layer formed in a surface portion of the semiconductor substrate directly under the tunnel insulating film, semi-fixed information is stored depending on an amount of charges in the charge storage layers, and charges opposite to the charges are induced in the surface portion.
