US Patent 7508708 NAND string with a redundant memory cell

The invention provides methods and apparatus. A NAND memory block has a source select line for selectively coupling one or more strings of series-coupled non-volatile memory cells to a source line, a drain select line for selectively coupling one or more strings of series-coupled non-volatile memory cells to one or more associated bit lines, a plurality of primary rows of memory cells interposed between the source select line and the drain select line and forming a portion of the one or more strings of series-coupled non-volatile memory cells, and one or more redundant rows of memory cells interposed between the source select line and the drain select line and forming a remaining portion of the one or more strings of series-coupled non-volatile memory cells.