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US 6,549,459 B2Granted
Method of managing a defect in a flash memory
AssigneeFujitsu Limited
InventorYoshinobu Higuchi
Life of this patent
Estimating the term…
Abstract
In a flash memory, error management units which store information on a physical occurrence position of an error which occurred during data reading are prepared by as much as the number of bits which can be corrected by an error correction code, in a redundant portion of a physical page. If the number of positions on which the error have occurred in a same physical page exceeds the number of the prepared error management units, then it is judged that the defect is uncorrectable.
Claims5
A method of managing a defect in a flash memory, said flash memory storing 1-bit information in a single cell, the method comprising the steps of:
- deciding whether an error has occurred, and if the error has occurred, deciding a number of errors occurring in a one physical page;
- deciding whether a number of memory cells corresponding to a plurality of bits to which the error has occurred in said one physical page exceeds a predetermined number that is equal to or smaller than the number of bits which can be corrected using an error correction code;
- and
- prohibiting use of a physical block including said one physical page for which it is decided that the number of memory cells exceeds the predetermined number.
1 more element
Dependencies are inferred from the claim text.