Nonvolatile semiconductor memory

摘要

According to one embodiment, in a nonvolatile semiconductor memory in which a charge store layer is formed on a tunnel insulating film formed on a channel region of a semiconductor substrate, a first nanoparticle layer containing first conductive nanoparticles is formed on the channel side, and a second nanoparticle layer containing a plurality of second conductive nanoparticles having an average particle size larger than the first conductive nanoparticles is formed on the charge store layer side. An average energy value ΔE1 required for charging one electron in the first conductive nanoparticle is smaller than an average energy value ΔE required for charging one electron in the second conductive nanoparticle, and a difference between ΔE1 and ΔE is larger than a heat fluctuation energy (kBT).

主权项

1. A nonvolatile semiconductor memory, comprising:
a first tunnel insulating film on a channel region of a semiconductor portion; a first nanoparticle layer on the first tunnel insulating film, comprising a first conductive nanoparticle satisfying a Coulomb blockade condition; a second tunnel insulating film on the first nanoparticle layer; a second nanoparticle layer on the second tunnel insulating film, comprising a second conductive nanoparticle satisfying the Coulomb blockade condition; a third tunnel insulating film on the second nanoparticle layer; a charge storage layer on the third tunnel insulating film; an insulating film on the charge storage layer; and a gate electrode on the insulating film, wherein the charge storage layer has an energy level of electron which is lower than an energy level of electron of the first and second nanoparticle layers when no voltage is applied between the gate electrode and the channel region, an average particle size (d) of a plurality of the second conductive nanoparticle is smaller than an average particle size (d1) of a plurality of the first conductive nanoparticle, an average energy value ΔE1 required for charging one electron in the first conductive nanoparticle is smaller than an average energy value ΔE required for charging one electron in the second conductive nanoparticle, 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 a difference between ΔE1 and ΔE is larger than a heat fluctuation energy (kBT).