Time-tagging read levels of multiple wordlines for open block data retention

A method of operating a non-volatile semiconductor memory device, the method comprising:

• acquiring a first set of read levels on a wordline of a first block of pages of a first set of memory cells;
• performing, using the first set of read levels, a first read operation on a page of a second block of pages of a second set of memory cells of the plurality of memory cells;
• determining whether a fail bit count of the page after the first read operation is above a threshold amount;
• in response to determining that the fail bit count of the page after the first read operation is above the threshold amount, acquiring a second set of read levels on a first wordline of the second block;
• performing, using the second set of read levels, a second read operation on the page;
• determining whether a fail bit count of the page after the second read operation is above the threshold amount;
• in response to determining that the fail bit count of the page after the second read operation is above the threshold amount, acquiring a third set of read levels on a second wordline of the second block;
• and
• performing, using the third set of read levels, a third read operation on the page.

An apparatus comprising:

• means for acquiring a first set of read levels on a wordline of a first block of pages of a first set of memory cells;
• means for performing, using the first set of read levels, a first read operation on a page of a second block of pages of a second set of memory cells of the plurality of memory cells;
• means for determining whether a fail bit count of the page after the first read operation is above a threshold amount;
• means for acquiring, in response to determining that the fail bit count of the page after the first read operation is above the threshold amount, a second set of read levels on a first wordline of the second block;
• means for performing, using the second set of read levels, a second read operation on the page;
• means for determining whether a fail bit count of the page after the second read operation is above the threshold amount;
• means for acquiring, in response to determining that the fail bit count of the page after the second read operation is above the threshold amount, a third set of read levels on a second wordline of the second block;
• and
• means for performing, using the third set of read levels, a third read operation on the page.