Leaky Memory Hole Repair via Dummy Word Line Programming
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Solution Overview
Problem
High-density memory devices face issues with charge leakage at fabrication joints, leading to programming difficulties and inaccurate results due to inter-memory channel leakage, especially caused by fabrication errors.
Innovation Solution
A memory device controller applies a detection voltage and counts bitlines responding to it, programming dummy word lines adjacent to fabrication joints with a specific threshold voltage to mitigate leakage by raising the threshold voltage of affected memory cells, thereby preventing incorrect programming and enhancing programming accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are packed into smaller areas to increase density, then memory capacity increases, but charge leakage at fabrication joints increases causing programming errors
Solution Approach 1:
The system performs preliminary detection of leakage-affected memory channels before programming operations. By identifying channels with fabrication joint leakage issues in advance and applying corrective voltage adjustments, the system prevents programming errors rather than correcting them afterward, thus maintaining both high density and programming accuracy
Solution Approach 2:
The system dynamically adjusts voltage parameters (such as pass voltage or program voltage) based on detected leakage characteristics of different memory channels. By changing electrical parameters adaptively, the system compensates for charge leakage effects at fabrication joints, enabling accurate programming in high-density configurations
2Quantity of substance
If fabrication joints are introduced to enable higher density arrays, then memory capacity increases, but inter-memory channel leakage increases causing programming difficulties
Solution Approach 1:
The system introduces an intermediary detection and control mechanism between the fabrication joint and the programming operation. This intermediary layer detects leakage signals and mediates by applying compensatory voltages, effectively decoupling the physical presence of fabrication joints from their harmful leakage effects, thus enabling high-density arrays to be programmed accurately
3Measurement precision
If detection voltage is applied to identify leaking channels, then programming accuracy improves, but additional detection steps increase operation time
Solution Approach 1:
The system merges the detection operation with the programming operation by performing leakage detection during idle periods or combining detection signals with programming signals. This integration allows the system to identify leaking channels without adding significant time overhead to the overall programming process, maintaining both accuracy and efficiency
Data Source
AI summary
A memory array with a fabrication joint includes a controller configured to apply a detection voltage on a word line coupled to a plurality of bitlines, count a number of bitlines having a first type of response to the detection voltage, and on condition that the number of bitlines exceeds a configured value, program memory cells on at least one dummy word line adjacent to the fabrication joint with a particular threshold voltage.