| 摘要 |
<p>PURPOSE:To obtain a constitution of a redundant memory cell for relieving a defective memory cell efficiently in a flash memory device. CONSTITUTION:Common source lines S1, S2,... are provided in memory cell groups L1, L2,... of a row unit. A redundant memory cell group LR of one row is provided so that it can be substituted with the row unit, sources of redundant memory cells are connected in common by a common source line SR. When a defect is detected in a first row L1 memory cell, the first row L1 is substituted with a redundant memory cell group LR. Since erasing voltage is not applied to a memory cell group of the substituted first row L1, an over erasing state is not caused, it is not made a depletion type, then a leakage current to a bit line through a memory cell of the first row L1 is eliminated. Therefore, substitution of a row unit can be performed..</p> |
