| 摘要 |
A nonvolatile semiconductor memory device includes a semiconductor substrate having at least one active region defined between two adjacent element-isolation regions and extending in a first direction, a first insulation film formed on a surface of the semiconductor substrate at the active region, and at least one memory cell transistor having a stacked gate structure including a floating gate and a control gate formed on the first insulation film and extending in a second direction intersecting the first direction. The floating gate has a center portion disposed on the active region, a first portion disposed adjacent to the center portion and extending in the second direction over one of the two adjacent element-isolation regions and a second portion disposed adjacent to the center portion and extending in the second direction over the other of the two adjacent element-isolation regions. The center portion and the first portion have a substantially uniform width as measured in the first direction while the second portion includes a portion having a width larger than that of the first portion.
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