| 摘要 |
<p>PURPOSE:To execute writing sufficiently at low voltage by applying high voltage to an erasing electrode, forcibly extracting a large amount of electrons in a floating gate electrode and charging the floating gate electrode at positive electricity. CONSTITUTION:DC power supplies 12-14 and switched 15-17 are each connected between a selective gate electrode 4 and a source electrode 8, between an erasing electrode and the source electrode and between a drain electrode 9 and the source electrode. A flating gate electrode 6 and a drain region 3 are capacitive-coupled intensely, and the potential of the electrode 6 is controlled by drain voltage. The power supply such as one 13 is set at approximately 10V and the power supply such as one 14 at zero V before writing operation, the switches such as ones 16, 17 are turned ON, and excess electrons in the electrode 6 are extracted and the electrode 6 is brought to an approximately neutral state. The switches are turned OFF, the power supply 12 is set at a value close by the threshold voltage of a first region and the power supply 14 at 5-10V and the switches 15, 16 are turned ON on writing. When the threshold voltage of a second channel region is set at 2-3V, surface potential on a boundary between both channels steeply changes.</p> |
