Patent ID: 8742489

Claim:
A nonvolatile semiconductor memory comprising: a first gate insulating film which is formed on a channel region of a semiconductor substrate; a first particle layer which is formed in the first gate insulating film and includes first conductive particles that satisfy Coulomb blockade conditions; a charge storage part which is formed on the first gate insulating film; a second gate insulating film which is formed on the charge storage part; a second particle layer which is formed in the second gate insulating film, includes second conductive particles that satisfy Coulomb blockade conditions, and differs from the first conductive particles in average particle diameter; and a gate electrode which is formed on the second gate insulating film, wherein the charge storage part has an energy level of electron which is lower than an energy level of electron of the first and second particle layers when no voltage is applied between the gate electrode and the channel region, an average energy ΔE 1 for charging one electron in the first conductive particles is smaller than an average energy ΔE for charging one electron in the second conductive particles, and is higher than an energy level of the channel region when no voltage is applied between the gate electrode and the channel region, and the difference between the average energy ΔE and the average energy ΔE 1 satisfies the following expression: Δ E−ΔE 1 >k B T where Boltzmann constant is k B and absolute temperature is T.