Cell-level realization of burn after reading for NAND flash
AssigneeWestern Digital Technologies, Inc.
InventorsZvonimir Z. Bandic, Robert Eugeniu Mateescu, Minghai Qin, Chao Sun
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Abstract
The present disclosure generally relates to a method of burning a file in a memory device after the file has been read. Once a file has been read, an algorithm uses the memory device to create errors that the error correction code (ECC) cannot decode the error. In creating the error, the entire word line is destroyed physically rather than logically so that retrieving information from that particular word line is no longer possible. In creating the error, adjacent word lines are not affected. The error renders the file burned.
Claims32
A method for use with a first memory device comprising a first file and a first bit coupled to a first word line, the first file comprising the first bit, the method comprising:
- determining that the first file has been read from the first memory device;
- and
- changing a logic state of the first bit after a first predetermined period of time, wherein the first word line, after changing the logic state, comprises a raw bit error rate that requires for correction an error correction code (ECC) rate of less than 0.9.
A computer system for storing and retrieving files, comprising:
- a processor;
- and
- a memory system comprising a first memory device that includes a first file and a first bit coupled to a first word line, the first file comprising the first bit, the memory system storing instructions that, when executed by the processor, cause the computer system to:
- determine that the first file has been read from the first memory device;
- and
- change a logic state of the first bit after a first predetermined period of time, wherein the first word line, after changing the logic state, comprises a raw bit error rate that requires for correction an error correction code (ECC) rate of less than 0.9.
A non-transitory computer readable storage medium, containing instructions that, when executed by a processor, cause a computer system to burn files after a read process has been completed for a first memory device comprising a first file and a first bit coupled to a first word line, the first file comprising the first bit, by performing the steps of:
- determining that the first file has been read from the first memory device;
- and
- changing a logic state of the first bit after a first predetermined period of time, wherein the first word line, after changing the logic state, comprises a raw bit error rate that requires for correction an error correction code (ECC) rate of less than 0.9.
A first memory device comprising:
- a first file and a first bit coupled to a first word line, the first file comprising the first bit;
- means for determining that the first file has been read from the first memory device;
- and
- means for changing a logic state of the first bit after a first predetermined period of time, wherein the first word line, after changing the logic state, comprises a raw bit error rate that requires for correction an error correction code (ECC) rate of less than 0.9.
Dependencies are inferred from the claim text.