Non-volatile memory with short prevention
AssigneeSanDisk Technologies LLC
InventorsYihang Liu, Xiaochen Zhu, Lito De La Rama, Feng Gao
Life of this patent
Estimating the term…
Abstract
To prevent loss of data due to a word line to memory hole short (or another defect), it is proposed to perform an erase process for a plurality of memory cells, detect that a subset of the plurality of memory cells are slow to erase, and prevent successfully programming for at least some of the memory cells that are slow to erase. This technique uses the erase process to predict future word line to memory hole shorts and prevent programming of memory cells predicted to have a future word line to memory hole short so no data will be lost when the short manifests.
Claims20
A non-volatile storage apparatus, comprising:
- a plurality of non-volatile memory cells;
- and
- a control circuit connected to the non-volatile memory cells, the control circuit is configured to:
- perform an erase process for the plurality of non-volatile memory cells,
- detect that a subset of the plurality of non-volatile memory cells are slow to erase in response to the erase process, and
- prevent successful programming for at least some of the non-volatile memory cells that are slow to erase.
A method, comprising:
- performing an erase process for a plurality of groups of connected non-volatile memory cells;
- detecting groups of connected memory cells that are slow to erase;
- identifying adjacent pairs of detected groups;
- and
- preventing identified adjacent pairs of detected groups from successfully programming.
A non-volatile storage apparatus, comprising:
- a three dimensional block of non-volatile memory cells arranged as NAND strings;
- bit lines connected to the NAND strings;
- and
- a control circuit connected to the block and the bit lines, the control circuit is configured to:
- perform an erase process on the block,
- detect NAND strings that include one or more memory cells with threshold voltages higher than a test value,
- determine whether the amount of detected NAND strings is greater than a limit,
- remove the block from use for storing external data if the amount of detected NAND strings is greater than the limit, and
- identify adjacent pairs of bit lines connected to detected NAND strings and increase threshold voltage of select gates of detected NAND strings that are connected to the identified adjacent pairs of bit lines to make the detected NAND strings that are connected to the identified adjacent pairs of bit lines unprogrammable if the amount of detected NAND strings is not greater than the limit.
Dependencies are inferred from the claim text.