Scrub techniques for use with dynamic read
First Claim
1. A method of operating a non-volatile memory system, the memory system including a controller circuit and one or more non-volatile memory circuits having a plurality of physical units of one or more blocks, the method comprising:
- maintaining a set of read parameters for use in reading operations of memory cells of the memory circuits, the set of read parameters including read parameters for a default read case and read parameters for a plurality of distinct, shifted read cases;
for each of the physical units, maintaining a correspondence between the physical unit and a which of the read cases to use when reading the physical unit;
performing a read operation for a page of data using the corresponding read case for the physical unit to which page belongs;
determining whether the read operation was successful or yielded a fail result;
in response to a read operation yielding a fail result, selecting a shifted read case at which the page can be read; and
based on the shifted read case selected, determining whether to refresh the block to which the page belongs.
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Accused Products
Abstract
The decision on whether to refresh or retire a memory block is based on the set of dynamic read values being used. In a memory system using a table of dynamic read values, the table is configured to include how to handle read error (retire, refresh) in addition to the read parameters for the different dynamic read cases. In a refinement, the read case number can used to prioritize blocks selected for refresh or retire. In cases where the read scrub is to be made more precise, multiple dynamic read cases can be applied. Further, which cases are applied can be intelligently selected.
184 Citations
21 Claims
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1. A method of operating a non-volatile memory system, the memory system including a controller circuit and one or more non-volatile memory circuits having a plurality of physical units of one or more blocks, the method comprising:
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maintaining a set of read parameters for use in reading operations of memory cells of the memory circuits, the set of read parameters including read parameters for a default read case and read parameters for a plurality of distinct, shifted read cases; for each of the physical units, maintaining a correspondence between the physical unit and a which of the read cases to use when reading the physical unit; performing a read operation for a page of data using the corresponding read case for the physical unit to which page belongs; determining whether the read operation was successful or yielded a fail result; in response to a read operation yielding a fail result, selecting a shifted read case at which the page can be read; and based on the shifted read case selected, determining whether to refresh the block to which the page belongs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification