| 摘要 |
<p>PURPOSE:To prevent the disappearance of stored information of a replacement information storage circuit and to secure a long service life. CONSTITUTION:During a normal operation, plural memory transistors, whose source and control gate electrodes are held to a ground potential and drain electrodes are held to the potential lower than a power supply potential by a prescribed potential and which are made to a depression type or an enhancement type in accordance with the charge accumulation condition of floating gates, are provided with a replacement information storage circuit 5 which stores identification information of cell array blocks including the presence and the absence of defective cells and the defective cells. Moreover, a redundant selecting circuit 6, which outputs redundancy selection signal RS that becomes an active level when it is judged that a cell array block containing a defective cell is selected based on the storage information of the circuit 5, is provided. The electric field intensity applied to the accumulated charges of floating gates of the memory transistors is made small and the loss of accumulated charges, i.e., the disappearance of stored information is prevented.</p> |
