Cell device and cell string for high density NAND flash memory

摘要

The invention relates a cell device and a cell string for high density flash memory. The cell string includes a plurality of cell devices and switching devices connected to ends of the plurality of cell devices. The cell device includes a semiconductor substrate, an insulating film, a charge storage node composed of nano-sized dots, a control insulating film and a control electrode which are sequentially formed on the semiconductor substrate, without source/drain regions. In the cell string, the silicon substrate enables easy formation of an inversion layer acting as the source/drain regions. The switching device does not include a source or drain region at a side connected to an adjacent cell device but includes a source or drain region at the side opposite to the side connected to the adjacent cell device. The invention improves miniaturizability and performance of cell devices for NAND flash memory, and induces an inversion layer by using a fringing electric field generated from the control electrode and the charge storage node, thus allowing for electrical connection between cells or between cell strings.