| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To achieve a higher speed for erasure processing without making external control complicated in a nonvolatile semiconductor memory device provided with a plurality of memory blocks where a plurality of electrically writable and erasable nonvolatile memory cells are arranged in an array form to enable batch data erasure, and redundant blocks to replace the memory blocks. <P>SOLUTION: This device is provided with a control circuit for determining whether defective blocks are included in a plurality of erasure object memory blocks upon reception of a redundant block replacing signal, performing control to switch the number of blocks where voltage application of erasing operation time simultaneously occurs to normal blocks so as to prevent voltage application of erasing operation time in defective blocks during an erasure operation in the normal blocks other than the defective blocks when the defective blocks are included, individually erasing the normal and redundant blocks, and performing control to simultaneously apply erasure voltages to all the erasure target memory blocks when no defective block is included. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
