NONVOLATILE SEMICONDUCTOR MEMORY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device that includes a transistor having low resistance of a gate electrode.SOLUTION: A nonvolatile semiconductor memory device includes a semiconductor substrate and a memory cell transistor capable of writing and erasing of electrical data. The nonvolatile semiconductor memory device further includes a memory cell unit having the memory cell transistor and a first selection gate transistor connected to one end of the memory cell transistor. A gate electrode of the memory cell transistor includes a stack of a floating gate electrode being electrically floated and a control gate electrode. A gate electrode of the first selection gate transistor has a lower electrode being electrically floated and an upper electrode. The gate electrode of the first selection gate transistor has a side-wall electrode on its side-wall portion that faces the upper electrode, the lower electrode, and the semiconductor substrate via an insulating film.