Redundant Bit Patterns for Column Defects Coding
AssigneeAtmel Corporation
InventorsMarc Merandat, Yves Fusella
Life of this patent
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Abstract
Techniques for coding and decoding redundant coding for column defects cartography. Defective cell groups identified in a memory array are redundantly encoded with a different bit pattern than the bit pattern used for functional cell groups. The identified defective cell groups are repaired using redundant cell groups in the memory array. The defective cell groups are later re-identified by checking the redundant bit pattern encoded in the cell groups. If new defective cell groups are identified, the memory array is identified as failing. If no new defective cell groups are identified, the memory array is identified as passing, and the identified defective cell groups are repaired.
Claims42
A method comprising:
- determining a number of defective columns in a memory array;
- encoding defective and non-defective columns in the memory array with redundant bit patterns;
- and
- storing the number of defective columns in a location of the memory array.
A method comprising:
- for each cell group in a set of cell groups of a memory array:
- determining whether the cell group is defective;
- if the cell group is not defective, storing a first value in a first cell location of the cell group and a second value in a second cell location of the cell group;
- and
- if the cell group is defective, storing a third value that is opposite of the first value in the first cell location of the cell group and storing a fourth value that is opposite of the second value in the second cell location of the cell group.
A computer-readable medium having instructions stored thereon, which, when executed by a processor, causes the processor to perform operations comprising:
- for each cell group in a set of cell groups of a memory array:
- if the cell group is not defective, storing a first value in a first cell location of the cell group and a second value in a second cell location of the cell group;
- if the cell group is defective, determining if the first cell location of the cell group is set to the first value and determining if the second cell location of the cell group is set to the second value;
- if the first cell location of the cell group is set to the first value and the second cell location of the cell group is set to the second value, indicating that the memory array fails;
- and
- if the first cell location of the cell group is not set to the first value or the second cell location of the cell group is not set to the second value, storing a third value that is opposite of the first value in the first cell location of the cell group and storing a fourth value that is opposite of the second value in the second cell location of the cell group.
A method comprising:
- for each cell group in a set of cell groups of a memory array:
- reading a first value in a first cell location of the cell group;
- reading a second value in a second cell location of the cell group;
- determining if the first value equals a third predetermined value;
- determining if the second value equals a fourth predetermined value;
- and
- if the first value differs from the third predetermined value or the second value differs from the fourth predetermined value indicating that the cell group is defective, storing an index of the defective cell group in a respective location of a register file.
A method comprising:
- determining a number of defective columns in a memory array by checking redundant bit patterns encoded in columns of the memory array;
- and
- if the number of defective columns does not exceed a number of reparation columns in the memory array, repairing the defective columns with reparation columns in the memory array.
A system comprising:
- a memory array;
- and
- a processor coupled to the memory array, the processor operable to perform operations comprising:
- determining a number of defective columns in the memory array by checking redundant bit patterns encoded in columns of the memory array;
- and
- if the number of defective columns does not exceed a number of reparation columns in the memory array, repairing the defective columns with reparation columns in the memory array.
A computer-readable medium having instructions stored thereon, which, when executed by a processor, causes the processor to perform operations comprising:
- for each column in a set of columns of a memory array:
- reading a first value in a first portion of the column;
- reading a second value in a second portion of the column;
- if the first and second values match a predefined bit pattern indicating that the column is defective, storing an index of the defective column in a respective location of a register file.
Dependencies are inferred from the claim text.