Soft errors handling in EEPROM devices

A solid-state memory system comprising:

• an array of memory cells, each cell capable of having at least one of its threshold voltages programmed or erased to an intended level within a range supported by the memory system;
• monitoring means invoked at at least one of a plurality of predefined events of the memory system for identifying one or more cells each having a threshold voltage shifted beyond a predetermined margin from its intended level;
• and
• writing means for re-writing said shifted threshold voltage back to its intended level;
• and
• wherein said plurality of predefined events of the memory system are memory operations on a portion of the memory array that are liable to perturb cells within said portion of the memory array.

A solid-state memory system comprising:

• an array of memory cells, each cell capable of having at least one of its threshold voltages programmed or erased to an intended level within a range supported by the memory system;
• monitoring means invoked at at least one of a plurality of predefined events of the memory system for identifying one or more cells each having a threshold voltage shifted beyond a predetermined margin from its intended level;
• and
• writing means for re-writing said shifted threshold voltage back to its intended level;
• and
• wherein:
• said memory array is partitioned into a plurality of sectors, each sector having cells that are all at a time subjected to one of said specific regular memory operations;
• and
• said monitoring means samples a predetermined number of sectors during each invocation, such that statistically each sector in the memory array gets monitored after at most a predetermined number of said plurality of predefined events.

In a solid-state memory system including an array of memory cells that are individually capable of having a threshold voltage programmed or erased to an intended level within a range supported by the memory system, wherein soft errors may arise from cells with a shifted threshold voltage, a method for detecting and correcting soft errors comprising the steps of:

• monitoring at at least one of a plurality of predefined events of the memory system to identify one or more cells each that individually have a threshold voltage shifted beyond a predetermined margin from said intended level;
• and
• re-writing said shifted threshold voltage back to said intended level;
• wherein
• said plurality of predefined events of the memory system include memory operations on a portion of the memory array that are liable to perturb cells in other portions of the memory array outside of said portion;
• and
• said monitoring samples one of a plurality of fractions of the memory array outside of said portion, such that statistically substantially all of said plurality of fractions of the memory array get monitored after at most a predetermined number of said sampling.

In a solid-state memory system including an array of memory cells, each cell capable of having at least one of its threshold voltages programmed or erased to an intended level within a range supported by the memory system, wherein soft errors may arise from cells with a shifted threshold voltage, a method for detecting and correcting soft errors comprising the steps of:

• monitoring at at least one of a plurality of predefined events of the memory system to identify one or more cells each having a threshold voltage shifted beyond a predetermined margin from its intended level;
• and
• re-writing said shifted threshold voltage back to its intended level;
• wherein said plurality of predefine events of the memory system are memory operations on a portion of the memory array that are liable to perturb cells within said portion of the memory array.

In a solid-state memory system including an array of memory cells, each cell capable of having at least one of its threshold voltages programmed or erased to an intended level within a range supported by the memory system, wherein soft errors may arise from cells with a shifted threshold voltage, a method for detecting and correcting soft errors comprising the steps of:

• monitoring at at least on of plurality of predefined events of the memory system to identify one or more cells each having a threshold voltage shifted beyond a predetermined margin from its intended level;
• and
• re-writing said shifted threshold voltage back to its intended level;
• wherein:
• said memory array is partitioned into a plurality of sectors, each sectors having cells that are all at a time subjected to one of said specific regular memory operations;
• and
• said monitoring means samples a predetermined number of sectors during each invocation, such that statistically each sector in the memory array gets monitored after at most a predetermined number of said plurality of predefined events.

A solid-state memory system comprising:

• an array of memory cells that are individually capable of having a threshold voltage programmed or erased to an intended level within a range supported by the memory system;
• monitoring means invoked by at least one of a plurality of predefined events of the memory system for identifying one or more cells that individually have a threshold voltage shifted beyond a predetermined margin from said intended level;
• and
• writing means for re-writing said shifted threshold voltage back to said intended level;
• wherein said plurality of predefined events of the memory system include memory operations on a portion of the memory array that are liable to perturb cells of the memory array outside of said portion;
• and
• wherein said monitoring means includes identification by error correction code of said one or more cells that individually have said shifted threshold voltage.

In a solid-state memory system including an array of memory cells that are individually capable of having a threshold voltage programmed or erased to an intended level within a range supported by the memory system, wherein soft errors may arise from cells with a shifted threshold voltage, a method for detecting and correcting soft errors comprising:

• monitoring at at least one of a plurality of predefined events of the memory system to identify one or more cells that individually have a threshold voltage shifted beyond a predetermined margin from said intended level;
• and
• re-writing said shifted threshold voltage back to said intended level;
• wherein said predefined events of the memory system include memory operations on a portion of the memory array that are liable to perturb cells in other portions of the memory array outside of said portion;
• and
• wherein said monitoring includes identifying by error correction code said one or more cells that individually have said shifted threshold voltage.