| 摘要 |
PROBLEM TO BE SOLVED: To increase capacitance at an interlayer insulating film, improve a coupling and lower the operation voltage, by arranging the interlayer insulating film surrounding the upper part and four side surfaces of a floating gate, and arranging a control gate surrounding the upper part and four side surfaces of the interlayer insulating film. SOLUTION: Source drain regions 130, 132 of a second conductivity type are formed on a first conductivity type semiconductor substrate. A first insulating film 106 is formed on a channel region formed between the source drain regions 130, 132, and a floating gate 108 is formed on the first insulating film 106. A second interlayer insulating film 124 is formed surrounding the upper part and four side surfaces in the direction of a word line and a bit line 142 of a floating gate 108. A control gate 154 is formed surrounding the upper part and four side surfaces of the second interlayer insulating film 124. As a result, capacitance at the second interlayer insulating film 124 is increased, a coupling ratio is improved, and an operating voltage of a nonvolatile memory element can be lowered.
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