| 摘要 |
A nonvolatile semiconductor storage device can achieve a shortened write time and a reduced absolute value of an operating voltage at the time of erasing. A P-type silicon substrate (1) is set at a ground level, a control gate (109) is set at a high voltage (Vp1), and a voltage of 0 V is applied to an access gate line connected in common to all access gates (7a) to set all the access gates (7a(n-4) to 7a(n+3)) at 0 V. When the threshold voltage of a memory transistor (MT(n)) is set into a written state, an N+ diffusion region (5(n)) is set at 0V. This causes tunnel injection of electrons into a floating gate (3a(n)) of the memory transistor (MT(n)) and thereby allows the memory transistor MT(n) to be set to a high threshold voltage (Vthp) without being influenced by the contents of writing to adjacent memory transistors.
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