| 摘要 |
Floating gates and control gates are alternately arranged on a substrate periodically in a first direction via a gate insulation film. Each floating gate has a first portion whose sectional shape is rectangular, and a second portion which is positioned substantially in a middle portion of the first portion and whose sectional shape is rectangular and whose length in a direction parallel to the first direction is smaller than that of the first portion. Each control gate has a third portion between the second portions of a pair of adjacent floating gates, and a fourth portion positioned between the first portions of a pair of adjacent floating gates. The floating gate and a pair of control gates positioned on opposite sides of the floating gate constitute one memory cell, the adjacent memory cells share the control gate positioned between the memory cells.
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