| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problem concerning the power source voltage lower limit arising from threshold voltage variation, unavoidable with a conventional nonvolatile semiconductor memory device for memorizing multiple values, and, thereby, to provide a high-performance nonvolatile semiconductor memory device consuming less power capable of fully performing and storing multiple values at low power source voltages, and, further, to provide a semiconductor device that includes the nonvolatile semiconductor memory device. <P>SOLUTION: The nonvolatile semiconductor memory device has elements which are different in write voltage or in erase voltage and are connected in parallel, and is capable of storing more than one bit by using only two different thresholds. The use of this design eliminates the power source voltage lower limit caused by threshold voltage variation and unavoidable in the past, and enables full performance at low power source voltages. A high-performance nonvolatile semiconductor memory device is realized in this way capable of consuming less power and storing multiple values. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
