US Patent 7362628 Semiconductor memory and redundancy repair method

In a semiconductor memory in which redundancy repair is carried out on a block basis, when a defective block of memory cells is replaced by a first redundant block, the adjacent normal block of memory cells closest to the defect, or a part of that normal block, is also replaced by memory cells in a second redundant block. This repair strategy provides a simple way to isolate a defective memory cell so that the defect does not affect non-replaced memory cells.