Patent ID: 7989871

Claim:
A nonvolatile semiconductor memory device comprising: first and second diffusion layers in a semiconductor substrate; a first insulating film on a channel which is provided between the first and second diffusion layers; a floating gate electrode on the first insulating film, which is formed by a conductive material; a second insulating film on the floating gate electrode; and a control gate electrode on the second insulating film, wherein the first insulating film comprises first and second layers, the first layer is directly in contact with the floating gate electrode and is formed by a first insulating material comprising a metal element having a d orbital, and the second layer is formed by a second insulating material comprising at least one selected from a group of a metal element without the d orbital and a semiconductor element, wherein the second insulating film comprises third and fourth layers, the third layer is directly in contact with the floating gate electrode and is formed by a third insulating material comprising a metal element having the d-orbital, and the fourth layer is formed by a fourth insulating material comprising at least one selected from a group of a metal element without the d-orbital and a semiconductor element, wherein each of the first and third insulating materials comprises oxide, nitride, oxynitride, silicate, silicate nitride, aluminate, or aluminate nitride comprising at least one element selected from a group of Hf, La, Y, Ce, Ti, and Zr, or their mixture or stack layer, wherein the first and third insulating materials are the same, and wherein each of the second and fourth insulating materials comprises oxide, nitride, or oxynitride comprising at least one element selected from a group of Al and Si, or their mixture or stack layer.