Matsushita Electric Industrial Co., Ltd.

Other

Nobuyo Sugiyama

Seiki Ogura

Shinji Odanaka

Hiromasa Fujimoto

A nonvolatile semiconductor memory device according to the present invention has a control gate electrode which is formed on the upper stage of a stepped portion formed in the principal surface of a substrate with a first insulating film interposed therebetween and a floating gate electrode which is formed to cover up the stepped portion, capacitively coupled to the side surface of the control gate electrode closer to the stepped portion with a second insulating film interposed therebetween, and opposed to the lower stage of the stepped portion with a third insulating film serving as a tunnel film interposed therebetween. Within the semiconductor substrate and in the vicinity of the stepped portion, there is formed a depletion control layer which is composed of a heavily doped impurity region and formed to extend from a position located under the floating gate electrode and at a distance from the upper corner of the stepped portion toward the lower corner of the stepped portion and adjoin the end portion of a drain region without reaching a step side region.

Nonvolatile semiconductor memory device and method for fabricating the same

The nonvolatile semiconductor memory device has a floating gate electrode that is formed on the semiconductor region and stores carriers injected from the semiconductor region and a control gate electrode that controls the quantity of stored carriers by applying a predetermined voltage to the floating gate electrode. The source region is formed in the semiconductor region on one of side regions of the floating gate electrode and control gate electrode, while the drain region is formed on the other of the side regions thereof. The drain region creates an electric field from which the carriers injected into the floating gate electrode are subject to an external force having an element directed from the semiconductor region to the floating gate electrode.

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Hyogo, Japan

Nobuyo Sugiyama