Storage Module Quarantine Annealing for Memory Cell Reliability
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Solution Overview
Problem
Charge trapped in the dielectric of memory cells reduces data retention and introduces errors in reading memory cells, with existing solutions either limiting program-erase cycles or shifting read thresholds, which can lead to errors in cells without trapped charge.
Innovation Solution
A storage module with a controller that identifies memory cells with high bit error rates due to trapped charge and quarantines them to allow heat-generated annealing, partially removing the trapped charge and improving data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of program-erase cycles is limited to manage trapped charge, then data retention reliability is improved, but memory usage and productivity are reduced
Solution Approach 1:
The system performs preliminary identification of memory cells with high bit error rates before they cause significant data retention failures. By detecting trapped charge conditions early and quarantining affected cells proactively, the system prevents reliability issues from developing while maintaining overall memory functionality and productivity.
2Measurement precision
If read scrub error thresholds are lowered to read true values in cells with trapped charge, then data accuracy in affected cells is improved, but errors are introduced in cells without trapped charge
Solution Approach 1:
The system extracts and isolates memory cells with trapped charge into a quarantine state, separating them from the operational memory population. This extraction allows the system to apply specialized read procedures only to quarantined cells while maintaining standard read thresholds for operational cells, thereby avoiding false errors in healthy cells.
Solution Approach 2:
The system applies different read procedures and error thresholds to different subsets of memory cells based on their operational status. Quarantined cells with trapped charge receive specialized low-threshold reading, while operational cells use standard thresholds, creating localized optimization without system-wide compromise.
3Measurement precision
If dynamic read or CVD tracking is performed to track distributions, then reading true values in cells with trapped charge is improved, but system complexity and processing time increase
Solution Approach 1:
By extracting cells with trapped charge into a quarantine state, the system eliminates the need for complex dynamic tracking procedures across the entire memory array. Only the quarantined subset requires specialized reading procedures, significantly reducing overall system complexity while maintaining the ability to read true values in affected cells.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The quarantine process enhances memory cell endurance and reduces flipped bit counts by naturally annealing the cells, improving data retention characteristics without introducing errors in cells without trapped charge.
Implementation Method 1
heat generated by the storage module anneals the set of memory cells to at least partially remove the trapped charge
Data Source
AI summary
A storage module and method are provided for using healing effects of a quarantine process. In one embodiment, a storage module is provided comprising a controller and a memory. The controller is configured to identify a set of memory cells in the memory that contains a bit error rate above a threshold, wherein the bit error rate is above the threshold due to trapped charge in dielectrics of the memory cells. The controller is also configured to quarantine the set of memory cells for a period of time, wherein while the set of memory cells is quarantined, heat generated by the storage module anneals the set of memory cells to at least partially remove the trapped charge.