3D Non-Volatile Memory Distortion Cancellation via Composite Accumulation
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Solution Overview
Problem
Three-dimensional non-volatile memory devices face significant interference issues due to cross-coupling effects, leading to distorted threshold voltages and reduced reading reliability, particularly in 3-D memory configurations where program disturb from multiple cells causes severe performance degradation.
Innovation Solution
A method is implemented to identify and estimate partial distortion components from potentially interfering memory cells, accumulate these components to produce a composite distortion, and cancel interference in target memory cells based on the estimated composite distortion, while discarding partial components to improve memory utilization and reduce memory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If distortion estimation and cancellation is performed in 3-D non-volatile memory, then storage reliability is improved, but memory resources are consumed
Solution Approach 1:
The distortion estimation process is segmented into multiple passes, where different groups of potentially-interfering memory cells are processed separately. Each pass estimates distortion from a specific group and accumulates the results, allowing the system to handle large numbers of interfering cells without requiring proportional memory resources.
Solution Approach 2:
The patent implements a mechanism where partial distortion components are discarded after being accumulated into the composite distortion estimate. The cache memory retains only the composite distortion and metadata about processed groups, discarding individual partial components to minimize memory usage while preserving the essential distortion information needed for cancellation.
2Measurement precision
If all potentially-interfering memory cells are processed simultaneously, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The set of potentially-interfering memory cells is divided into multiple groups that are processed in sequential passes. Each pass handles a manageable subset of cells, estimating their individual distortion contributions and accumulating these into a composite estimate. This segmentation reduces per-pass complexity while maintaining overall precision through multiple measurements.
Solution Approach 2:
The system performs preliminary identification of potentially-interfering memory cell groups before the actual distortion estimation. This preliminary action organizes the cells into manageable groups and prepares the processing structure, allowing the main estimation algorithm to operate on pre-organized data with reduced complexity.
3Measurement precision
If multiple groups of potentially-interfering memory cells are processed, then distortion cancellation accuracy is improved, but memory requirements increase
Solution Approach 1:
Partial distortion components from individual interfering cell groups are discarded after being accumulated into the composite distortion estimate. The cache memory stores only the composite distortion and metadata identifying processed groups, not the individual partial components. This approach maintains cancellation accuracy by preserving the cumulative effect while minimizing memory requirements by discarding redundant intermediate data.
Solution Approach 2:
The patent transforms the representation of distortion data from storing individual partial distortion components to storing only the composite distortion and group metadata. This parameter change in data representation maintains the information needed for accurate cancellation while dramatically reducing the memory resources required to store distortion estimation data.
Data Source
AI summary
A method in a memory that includes multiple analog memory cells arranged in a three-dimensional (3-D) configuration, includes identifying multiple groups of potentially-interfering memory cells that potentially cause interference to a group of target memory cells. Partial distortion components, which are inflicted by the respective groups of the potentially-interfering memory cells on the target memory cells, are estimated. The partial distortion components are progressively accumulated so as to produce an estimated composite distortion affecting the target memory cells, while retaining only the composite distortion and not the partial distortion components. The target memory cells are read, and the interference in the target memory cells is canceled based on the estimated composite distortion.