| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve disturb/retention characteristics by providing a memory transistor in which an amount of charges changes in accordance with an applied voltage to a word line and a bit line connected thereto, resulting in a change in a threshold voltage in accordance with the change in the amount of charges. SOLUTION: A multi-value data, ternary or higher data is recorded in a single memory transistor in accordance with a threshold voltage of the memory transistor. Upon read-out, data based on a word line voltage and an mount of accumulated charges, set in accordance with the threshold voltage, is output to a bit line. Two-bit data to be recorded in the single memory transistor is represented as [D2, D1], which can take either of four states: [1, 1], [0, 1], [1, 0], and [0, 0]. Two of the threshold voltages Vth are provided on the positive side, while two of them are provided in the negative side, resulting in a wide distribution range of the threshold voltages and wide data intervals. Thus, a writing control is made to be easier.</p> |
