US Patent 7180121 Semiconductor device and method of manufacturing the same

A semiconductor device includes a substrate including a semiconductor and a trench, and an electrically rewritable semiconductor memory cell on the substrate, the semiconductor memory cell comprising a charge storage layer including an upper surface and a lower surface, an area of the lower surface being smaller than an area of the upper surface, and at least a part of the charge storage layer being provided in the trench, first insulating layer between the lower surface of the charge storage layer and a bottom surface of the trench, second insulating layer between a side surface of the trench and a side surface of the charge storage layer and between the side surface of the trench and a side surface of the first insulating layer, third insulating layer on the charge storage layer, and a control gate electrode on the third insulating layer.