| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To make it possible to recover the defect caused by a short-circuit failure of a control gate and a source or a drain over aging in a nonvolatile semiconductor memory. <P>SOLUTION: A memory block has regular memory blocks (2, 3) and a spare memory block (3) for the regular memory blocks and a part of the normal memory block is made a storage area (4) of relief information. The well area of the memory block is separated from other memory blocks and nonvolatile memory cells which are electrically erasable and electrically writable are formed in the well area and the memory cells are made an erasure unit. When a control circuit 11 detects an access to the regular memory block shown by the relief information, the circuit switches the access to the regular memory block to an access to a corresponding spare memory block, and when the circuit detects occurrence of an erasure error, the circuit performs control for adding relief information which associates the memory block related to the error with the spare memory block. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
