NAND Program Pulse Duration Control for Programming Failures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Program failure in non-volatile memory cells, particularly in NAND strings, occurs due to early termination or failure to reach the maximum allowed program voltage, often caused by variations in cell programming speed, leading to incomplete data storage.
Innovation Solution
Increasing the duration of program pulses for memory cells that fail to program successfully using a default duration, either by extending the duration for the same group or applying additional pulses with longer durations to complete programming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the program pulse duration is increased for memory cells that fail to program successfully, then the programming success rate is improved, but the programming time is increased
Solution Approach 1:
The patent applies dynamics by making the program pulse duration adjustable rather than fixed. The system dynamically extends the pulse duration for specific memory cells that fail to program successfully, while maintaining the default shorter duration for cells that program successfully. This selective dynamic adjustment improves overall programming success rate without proportionally increasing the programming time for all cells.
Solution Approach 2:
The patent implements local quality by applying different program pulse durations to different memory cells based on their individual programming status. Instead of uniformly extending the pulse duration for all cells, the system identifies specific cells that failed to program and applies extended pulses only to those cells, thereby improving success rate locally without globally increasing programming time.
2Reliability
If the program voltage magnitude is increased to ensure complete programming, then the programming reliability is improved, but the risk of damaging memory cells increases
Solution Approach 1:
The patent applies parameter changes by modifying the program pulse duration parameter rather than increasing voltage magnitude. By extending the time duration of pulses at controlled voltage levels, the system achieves complete programming of stubborn cells without subjecting them to excessive voltage stress that could cause damage. This parameter substitution resolves the contradiction between programming completeness and cell safety.
Solution Approach 2:
The patent implements periodic action through iterative program-verify loops. Instead of applying a single high-voltage pulse, the system repeatedly applies program pulses followed by verification, gradually extending pulse duration for cells that fail verification. This periodic, incremental approach ensures complete programming while avoiding the harmful effects of excessive single-pulse voltage magnitudes.
Data Source
AI summary
A duration of a program pulse used to program non-volatile memory cells such as NAND may be increased responsive to a programming failure using a shorter duration program pulse. The duration of at least one program pulse may be increased for at least one group of memory cells in response to a failure to program a group using a default program pulse duration. The group that experiences the increased duration program pulse may be the same group for which the program operation failed using the shorter program pulse or may be a different group than the group for which the program operation failed using the shorter program pulse.