Countermeasure modes to address neighbor plane disturb condition in non-volatile memory structures
Countermeasure method for programming a non-defective plane of a non-volatile memory experiencing a neighbor plane disturb, comprising, once a first plane is determined to have completed programming of a current state but where not all planes have completed the programming, a loop count is incremented and a determination is made as to whether the loop count exceeds a threshold. If so, programming of the incomplete plane(s) is ceased and programming of the completed plane(s) is resumed by suspending the loop count and bit scan mode, and, on a next program pulse, applying a pre-determined rollback voltage to decrement a program voltage bias. The loop count and bit scan mode are resumed once a threshold voltage level equals a program voltage bias when the loop count was last incremented. BSPF criterion is applied for each programmed state. Advancement to the next loop only occurs if a programmed state is determined incomplete.
1. A countermeasure method for programming a non-defective memory plane of a non-volatile memory structure experiencing a neighbor plane disturb condition, the method comprising:
according to an initial programming sequence, initiating a program pulse for a current programming state and subsequently initiating a program verify operation;
initiating a bit scan mode according to a bit scan pass fail criterion;
once a first memory plane of the memory structure is determined to have completed programming of the current programming state according to the bit scan pass fail criterion, determining if all memory planes of the memory structure have completed programming of the current programming state;
when not all memory planes have completed programming of the current programming state, incrementing a loop count and determining if the loop count exceeds a pre-determined threshold value;
when the loop count exceeds the pre-determined threshold value:
ceasing programming of one or more memory planes having incomplete programming of the current programming state;
resuming programming of one or more memory planes having completed programming of the current programming state by:
temporarily suspending the loop count and the bit scan mode;
on a next program pulse, applying a pre-determined rollback voltage value to decrement a program voltage bias level otherwise expected during the program pulse according to the initial programming sequence;
resuming the loop count and the bit scan mode once a programmed threshold voltage level is equal to a program voltage bias level that was reached when the loop count was last incremented;
applying the bit scan pass fail criterion with respect to each programmed state; and
advancing to a next programming loop only upon determining a programmed state is incomplete according to the bit scan pass fail criterion.
2. The method according to claim 1 , wherein applying the bit scan pass fail criterion with respect to each programmed state and advancing to a next programming loop only upon determining a programmed state is incomplete occurs only in an initial programming loop after resuming the loop count and bit scan mode.
3. The method according to claim 1 , wherein applying the bit scan pass fail criterion with respect to each programmed state and advancing to a next programming loop only upon determining a programmed state is incomplete occurs in every programming loop after resuming the loop count and bit scan mode.
4. The method according to claim 1 , wherein the pre-determined threshold loop count value is indicative of the neighbor plane disturb condition.
5. The method according to claim 1 , wherein the pre-determined rollback voltage value is optimized according to resolution and efficiency parameters.
6. The method according to claim 1 , wherein the pre-determined rollback voltage value is associated with a step size increase in the program voltage bias level occurring during at least one of:
two programming loops;
four programming loops; and
eight programming loops.
7. The method according to claim 1 , wherein the program verify operation is a stage of a TLC-type programming sequence.
8. A memory controller, comprising:
a first port configured to couple to a non-volatile memory, the memory comprising a memory structure; and
the memory controller configured to perform a countermeasure during the programming of the memory structure experiencing a neighbor plane disturb condition, comprising:
according to an initial programming sequence, initiate a program pulse for a current programming state and subsequently initiate a program verify operation;
initiate a bit scan mode according to a bit scan pass fail criterion;
once a first memory plane of the memory structure is determined to have completed programming of the current programming state according to the bit scan pass fail criterion, determine if all memory planes of the memory structure have completed programming of the current programming state;
when not all memory planes have completed programming of the current programming state, increment a loop count and determine if the loop count exceeds a pre-determined threshold value;
when the loop count exceeds the pre-determined threshold value:
cease programming of one or more memory planes having incomplete programming of the current programming state;
resume programming of one or more memory planes having completed programming of the current programming state by:
temporarily suspending the loop count and the bit scan mode;
on a next program pulse, applying a pre-determined rollback voltage value to decrement a program voltage bias level otherwise expected during the program pulse according to the initial programming sequence;
resuming the loop count and the bit scan mode once a programmed threshold voltage level is equal to a program voltage bias level that was reached when the loop count was last incremented;
applying the bit scan pass fail criterion with respect to each programmed state; and
advancing to a next programming loop only upon determining a programmed state is incomplete according to the bit scan pass fail criterion.
9. The memory controller according to claim 8 , wherein applying the bit scan pass fail criterion with respect to each programmed state and advancing to a next programming loop only upon determining a programmed state is incomplete occurs only in an initial programming loop after resuming the loop count and bit scan mode.
10. The memory controller according to claim 8 , wherein applying the bit scan pass fail criterion with respect to each programmed state and advancing to a next programming loop only upon determining a programmed state is incomplete occurs in every programming loop after resuming the loop count and bit scan mode.
11. The memory controller according to claim 8 , wherein the pre-determined threshold loop count value is indicative of the neighbor plane disturb condition.
12. The memory controller according to claim 8 , wherein the pre-determined rollback voltage value is optimized according to resolution and efficiency parameters.
13. The memory controller according to claim 8 , wherein the pre-determined rollback voltage value is associated with a step size increase in the program voltage bias level occurring during at least one of:
two programming loops;
four programming loops; and
eight programming loops.
14. The memory controller according to claim 8 , wherein the program verify operation is a stage of a TLC-type programming sequence.
15. A non-volatile memory system, comprising:
a memory structure;
a memory controller coupled to the memory structure and:
according to an initial programming sequence, initiating a program pulse for a current programming state and subsequently initiating a program verify operation;
initiating a bit scan mode according to a bit scan pass fail criterion;
once a first memory plane of the memory structure is determined to have completed programming of the current programming state according to the bit scan pass fail criterion, determining if all memory planes of the memory structure have completed programming of the current programming state;
when not all memory planes have completed programming of the current programming state, incrementing a loop count and determining if the loop count exceeds a pre-determined threshold value;
when the loop count exceeds the pre-determined threshold value:
ceasing programming of one or more memory planes having incomplete programming of the current programming state;
resuming programming of one or more memory planes having completed programming of the current programming state by:
temporarily suspending the loop count and the bit scan mode;
on a next program pulse, applying a pre-determined rollback voltage value to decrement a program voltage bias level otherwise expected during the program pulse according to the initial programming sequence;
resuming the loop count and the bit scan mode once a programmed threshold voltage level is equal to a program voltage bias level that was reached when the loop count was last incremented;
applying the bit scan pass fail criterion with respect to each programmed state; and
advancing to a next programming loop only upon determining a programmed state is incomplete according to the bit scan pass fail criterion.
16. The non-volatile memory system according to claim 15 , wherein applying the bit scan pass fail criterion with respect to each programmed state and advancing to a next programming loop only upon determining a programmed state is incomplete occurs only in an initial programming loop after resuming the loop count and bit scan mode.
17. The non-volatile memory system according to claim 15 , wherein applying the bit scan pass fail criterion with respect to each programmed state and advancing to a next programming loop only upon determining a programmed state is incomplete occurs in every programming loop after resuming the loop count and bit scan mode.
18. The non-volatile memory system according to claim 15 , wherein the pre-determined threshold loop count value is indicative of the neighbor plane disturb condition.
19. The non-volatile memory system according to claim 15 , wherein the pre-determined rollback voltage value is optimized according to resolution and efficiency parameters.
20. The non-volatile memory system according to claim 15 , wherein the pre-determined rollback voltage value is associated with a step size increase in the program voltage bias level occurring during at least one of:
two programming loops;
four programming loops; and
eight programming loops.