| 摘要 |
<p>PURPOSE:To control the dispersion of threshold voltage after erasion among a plurality of storage elements by returning the specified threshold voltage in the lump, making use of the feedback mechanism between the quantity of electrons injected into a floating gate electrode using an FN current and the potential of a floating electrode. CONSTITUTION:A plurality of storage elements are erased excessively by the first Fowler-Nordein tunnel current flowing in the first gate insulating film 12 by applying first voltage of electric pulses between a source region 17 and a control gate electrode 15. Hereby, it gets in deep erasion state such as that the center of the distribution of the threshold voltages of a plurality of storage elements has passed over the specified erasion threshold voltage value. After that, the center of the distribution of the threshold voltages of a plurality of storage elements is suited to the specified erasing voltage value by the first Fowler-Nordheim tunnel current flowing in the first gate insulating film 12 by applying second voltage of electric pulses between an impurity region and a control gate electrode.</p> |
