Memory with retargetable memory cell redundancy
First Claim
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1. A nonvolatile memory array, comprising:
- a first column of memory cells that contains a defective cell and nondefective cells;
a second column of memory cells that is a redundant column that contains only data relocated from outside the second column of memory cells; and
the defective cell individually mapped to a redundant cell in the second column such that data to be stored in the defective cell is stored in the redundant cell, the defective cell and the redundant cell in the same row, the second column containing no data mapped from the nondefective cells of the first column.
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Abstract
In a memory array having redundant columns, a scheme allows defective cells to be individually remapped to redundant cells in a redundant column. Redundant cells in one redundant column replace defective cells in multiple non-redundant columns. Remapping is done as part of initial test and configuration. Specific hardware can be used for the scheme or firmware in the memory controller can implement the scheme.
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Citations
17 Claims
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1. A nonvolatile memory array, comprising:
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a first column of memory cells that contains a defective cell and nondefective cells;
a second column of memory cells that is a redundant column that contains only data relocated from outside the second column of memory cells; and
the defective cell individually mapped to a redundant cell in the second column such that data to be stored in the defective cell is stored in the redundant cell, the defective cell and the redundant cell in the same row, the second column containing no data mapped from the nondefective cells of the first column. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A nonvolatile NAND flash memory array, comprising:
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a first column of NAND strings that contains a defective string and nondefective strings;
a second column of NAND strings that is a redundant column that contains only data relocated from outside the second column of NAND strings; and
the defective NAND string individually mapped to a redundant NAND string in the second column such that data to be stored in the defective NAND string is stored in the redundant NAND string, the second column containing no data mapped from the nondefective NAND strings of the first column. - View Dependent Claims (16, 17)
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Specification