US 2015/0309857 A1 · Imminent Read Failure Detection Based Upon Unacceptable Wear For NVM Cells

Abstract

Methods and systems are disclosed for imminent read failure detection based upon unacceptable wear for non-volatile memory (NVM) cells. In certain embodiments, a first failure time is recorded when a first diagnostic mode detects an uncorrectable error within the NVM cell array using a first set of read voltage levels below and above a normal read voltage level. A second failure time is recorded when a second diagnostic mode detects an uncorrectable error within the NVM cell array using a second set of read voltage levels below and above a normal read voltage level. The first and second failure times are then compared against a threshold wear time value to determine whether or not an imminent read failure is indicated. The diagnostic modes can be run separately for erased NVM cell distributions and programmed NVM cell distributions to provide separate wear rate determinations.

Claims20

Dependent claims

A method for detecting imminent read failures for a non-volatile memory (NVM) system, comprising:

periodically performing read operations for a first diagnostic mode for an array of non-volatile memory (NVM) cells until a first uncorrectable read error is detected at a first time;
periodically performing read operations for a second diagnostic read mode for the array of NVM cells until a second uncorrectable read error is detected at a second time;
comparing a difference between the second time and the first time with a threshold time value;
and
indicating an imminent read failure for the array of NVM cells based upon the comparison.

2 more elements

A non-volatile memory (NVM) system having imminent read failure detection, comprising:

a non-volatile memory (NVM) including an array of NVM cells;
a memory management unit coupled to the array of NVM cells;
a controller within the memory management unit coupled to the NVM and configured to perform read operations for the NVM cells;
the controller being configured to periodically perform read operations for a first diagnostic mode for the array of NVM cells until a first uncorrectable read error is detected at a first time;
the controller being further configured to periodically perform read operations for a second diagnostic read mode for the array of NVM cells until a second uncorrectable read error is detected at a second time;
and
the controller being further configured to compare a difference between the second time and the first time with a threshold time value and to indicate an imminent read failure for the array of NVM cells based upon the comparison.

4 more elements

Dependencies are inferred from the claim text.

Imminent Read Failure Detection Based Upon Unacceptable Wear For NVM Cells

Life of this patent

Imminent Read Failure Detection Based Upon Unacceptable Wear For NVM Cells

Life of this patent

Abstract

Claims20