Memory Program Verify Compensation for Defective Deck Blocks
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Solution Overview
Problem
Memory devices with defective decks experience increased error rates due to threshold voltage shifts and leakage currents, leading to inefficient program verify operations and read disturbances, especially in partially functional blocks with both functional and defective decks.
Innovation Solution
Adaptive adjustment of program verify parameters during the program verify phase to compensate for defective decks by programming memory cells to higher voltage levels, reducing string current and mitigating threshold voltage distribution shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory cells are programmed using standard verify parameters, then programming speed is maintained, but error rates increase due to threshold voltage shifts in partially functional blocks
Solution Approach 1:
The patent dynamically adjusts the program verify parameter based on the operational status of decks. When a partially functional block is detected (containing both functional and defective decks), the system automatically modifies the verify parameter from a standard value to an adjusted value that compensates for threshold voltage shifts, thereby resolving the contradiction between maintaining programming efficiency and reducing error rates.
Solution Approach 2:
The invention changes the program verify parameter value according to the deck configuration. For partially functional blocks, a different verify parameter is applied compared to fully functional blocks, allowing the system to adapt to varying operational conditions and mitigate threshold voltage distribution shifts without significantly impacting overall programming performance.
2Reliability
If standard program verify parameters are used in partially functional blocks, then processing simplicity is maintained, but threshold voltage distribution shifts cause read disturbances
Solution Approach 1:
The system implements feedback by detecting the operational status of decks and using this information to determine the appropriate program verify parameter. The controller monitors whether blocks are fully functional or partially functional and automatically selects the corresponding verify parameter, providing feedback-based adaptation that improves read accuracy without requiring complex manual intervention.
Solution Approach 2:
The memory system performs self-adjustment by automatically identifying partially functional blocks and applying the appropriate verify parameter without external intervention. The controller autonomously determines the deck status and selects the correct programming parameters, enabling the system to self-correct for threshold voltage shifts and maintain read accuracy.
3Reliability
If higher program verify parameters are applied to compensate for defective decks, then threshold voltage shifts are mitigated, but string current increases causing additional leakage
Solution Approach 1:
The patent applies different program verify parameters to different blocks based on their specific deck configuration. Instead of uniformly increasing the verify parameter across the entire memory device, the system locally adjusts parameters only for partially functional blocks where needed, thereby mitigating threshold voltage shifts in those specific areas while avoiding unnecessary current increases in fully functional blocks.
Data Source
AI summary
A request to perform a program operation to program a set of memory cells on a memory device is received. A defect indicator associated with the set of memory cells is determined to satisfy a defect condition. A value of a program verify parameter is determined based on the defect indicator. The program operation is performed using the value of the program verify parameter during a program verify phase of the program operation.