| 摘要 |
PURPOSE: A semiconductor memory device having a redundancy cell block tp improve redundancy efficiency is provided to improve the redundancy efficiency by replacing a defective memory cell with a redundancy cell of a redundancy cell block which is always activated. CONSTITUTION: A redundancy cell block(250) has a plurality of redundancy cells(RED20,RED21,RED22,RED23) for replacing a memory cell in case of a failure in the memory cell within a plurality of memory cell blocks(210,220,230,240). One of the plurality of memory cell blocks(210,220,230,240) is activated in response to a predetermined select signal. The redundancy cell block(250) is activated regardless of activation of the memory cell blocks(210,220,230,240).
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