Method of forming a memory cell of a nonvolatile semiconductor memory

Abstract

A method is provided for forming a memory cell in a nonvolatile semiconductor memory device having MOSFET configuration from a data memory section having two-layer gate construction and series select transistors formed between a control gate connected to the data memory section and the exposed side walls of the semiconductor substrate. According to this method, a polycrystalline semiconductor film that forms floating gates and an underlying gate oxide film are processed by dry etching using a photoresist. Next, the semiconductor substrate is cut to a prescribed depth by dry etching to expose side walls of the semiconductor substrate, following which impurities are ion injected into the semiconductor substrate to form a diffused impurity layer. Finally, an intergate insulation film that forms a control gate and a polycrystalline semiconductor film are stacked and processed.