| 摘要 |
<p>A nonvolatile semiconductor storage device has a memory array constituted by arranging a plurality of memory cells each including a gate insulating film, a floating gate electrode, an inter-electrode layer insulating film, and a control gate electrode on a semiconductor region of a first conductivity type, source and drain regions of a second conductivity type in the semiconductor region of the first conductivity type. Information is written/erased by controlling the quantity of charge in the floating gate electrode. The storage device further has at least a means which applies a prescribed first operating voltage across the memory cells for injecting/ejecting charge from the floating gate electrode, a means which applies a second voltage across the memory cells for giving an electric field of the opposite polarity of the electric field given by the first operating voltage to an insulating film region around the floating gate which the charge has passed when the first operating voltage is applied after the first operating voltage is applied, a means which verifies the threshold voltage of the memory cells after the second voltage is applied, and a means which judges whether or not the operations after the first operating voltage is applied are to be repeated again after the verification.</p> |
