| 摘要 |
<p>PROBLEM TO BE SOLVED: To make data equivalent to two bits storable and rewritable by make a MOS transistor to be in four states in which electrons are injected into the charge storage layer of the drain side or the source side of the MOS transistor or electrons are injected into both charge storage layers of the drain side and the source side or not. SOLUTION: A MOS transistor is made to be in first to third write states by setting threshold voltage of one part of channel regions of the drain side and the source side of the transistor and the threshold voltage of the channel region of the draind side or the source side low or high while making the gate or the source or the drain to be at 0 volt and setting the drain and the source or the drain and the gate or the source and the gate to be a high voltage and releasing electrons from a silicon nitride film 2 adjacent to the drain and the source into the drain and the source or injecting electrons from the neighborhood of the drain or a source side channel region into the silicon nitride film 2. Moreover, in order to set the transistor in a fourth write state, voltages of the drain side and the source side are set to high threshold voltages by injecting electrons into the silicon nitride film 2 while making the side in which the electrons are injected to be at 0 V at the side in which the injection is not present to be at a high voltage. Thus, the four states of the transistor are set.</p> |
