Patent ID: 7943984

Claim:
A nonvolatile semiconductor memory apparatus comprising: a memory element including: a semiconductor layer; a source region and a drain region formed at a distance from each other in the semiconductor layer; a first insulating film formed on a portion of the semiconductor layer located between the source region and the drain region, the first insulating film having first sites that perform electron trapping and releasing and are formed by adding an element different from a material of the first insulating film, and energy levels of the first sites being higher than a Fermi level of a material forming the semiconductor layer; a charge storage film formed on the first insulating film; a second insulating film formed on the charge storage film; and a control gate electrode formed on the second insulating film, wherein the first insulating film includes a first insulating layer and a second insulating layer formed on the first insulating layer, the second insulating layer having a higher dielectric constant than the first insulating layer, and includes the first sites that perform the electron trapping and releasing, and wherein: T 1,low represents a physical thickness of the first insulating layer when the first insulating film is the first insulating layer and the first insulating layer needs to reduce leakage current to J low or lower, leakage current of the first insulating film in a first electric field applied in the first insulating film being required to be J low or lower as a required condition in a charge retaining state, T 2,low represents a physical thickness of the second insulating layer when the first insulating film is the second insulating layer and the second insulating layer needs to reduce leakage current to J low or lower, leakage current of the first insulating film in a first electric field applied in the first insulating film being required to be J low or lower as the required condition in the charge retaining state, T 1,high represents a physical thickness that the first insulating layer needs to have to increase the leakage current of the first insulating film to J high or higher in a second electric field applied in the first insulating film as a condition required when writing is performed; ∈ 1 and ∈ 2 represent dielectric constants of the first insulating layer and the second insulating layer, ∈ ox represents a dielectric constant of silicon oxide, and T 1 (nm) and T 2 (nm) represent the respective physical thicknesses of the first insulating layer and the second insulating layer that are stacked, and the first insulating layer and the second insulating layer have physical thicknesses that fall into ranges that satisfy the following three inequations T 2 ≧−( T 2,low /T 1,low )× T 1 +T 2,low T 1 ≧T 1,high T 1 ×∈ ox /∈ 1 +T 2 ×∈ ox /∈ 2 ≦8.