Patent ID: 7842992

Claim:
A nonvolatile semiconductor memory device comprising: a substrate; a base insulating layer over the substrate; a semiconductor layer over the base insulating layer, the semiconductor layer including a channel forming region between a first impurity region and a second impurity region which are formed apart from each other; a first insulating layer over the channel forming region; a floating gate over the channel forming region with the first insulating layer interposed therebetween; a second insulating layer over the floating gate; and a control gate over the floating gate with the second insulating layer interposed therebetween, wherein the floating gate includes at least a first layer which is in direct contact with the first insulating layer and a second layer formed over the first layer, wherein the first layer comprises germanium or a germanium compound, and wherein the second layer is formed of a material selected from the group consisting of a metal, an alloy, and a metal compound which is different from the germanium or the germanium compound.