NONVOLATILE SEMICONDUCTOR MEMORY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a new solution measure to a disturbance problem for realizing reduction in array size. SOLUTION: A memory cell, in which asymmetric source 118 and drain 116 regions are arrayed together with a floating gate 100 on a semiconductor substrate, is formed to the semiconductor substrate. A non-tunnel region is formed between the source and the floating gate by the bird's beak encroachment of a thermal oxide on the source side of the cell. A source disturbance is stopped by a thick tunnel oxide on the source side due to the encroachment of a bird's beak. There is no bird's beak encroachment on the drain side. A thin tunnel 122 region corresponds to high programming speed on the drain side of the cell. A memory is programmed, and the hindrances of the cell adjacent to the cell to be erased or read is reduced.