State-Dependent Read Compensation for Flash Memory
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Solution Overview
Problem
As storage density increases in data storage devices like flash memory, cells become more susceptible to variations due to factors such as cell damage, charge leakage, and manufacturing differences, leading to instability in reading encoded data.
Innovation Solution
The implementation of state-dependent read compensation, where a controller performs read operations on adjacent word lines to determine a read setting for a target word line, adjusting parameters like sense time and source voltage based on the results of these reads to compensate for lateral charge diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If storage density is increased, then storage capacity is improved, but read accuracy deteriorates due to increased susceptibility to cell damage, charge leakage, and manufacturing differences
Solution Approach 1:
The system performs preliminary read operations on adjacent word lines before reading the target word line. These preliminary reads detect charge diffusion states in neighboring cells, allowing the system to pre-adjust read thresholds and parameters for the target word line, thereby compensating for anticipated interference and maintaining read accuracy despite high storage density
Solution Approach 2:
The system uses read results from adjacent word lines as feedback to dynamically adjust read parameters for the target word line. The controller analyzes charge diffusion patterns from neighboring cells and modifies read thresholds accordingly, creating a closed-loop system that maintains measurement precision even as storage density increases
2Quantity of substance
If storage density is increased, then storage capacity is improved, but read stability deteriorates due to lateral charge diffusion between cells
Solution Approach 1:
The system applies different read parameters to different spatial locations within the memory array. By detecting charge diffusion patterns in specific adjacent cells and applying localized threshold adjustments only to affected areas, the system maintains read stability without requiring global parameter changes, thus preserving storage density while combating lateral charge diffusion
Solution Approach 2:
The system dynamically changes read parameters (thresholds, sense amplification levels) based on detected charge diffusion states. When lateral charge diffusion is detected in adjacent cells, the system adjusts read parameters for the target word line to compensate, maintaining read stability despite the physical constraints of high-density storage
Data Source
AI summary
Apparatuses, systems, methods, and computer program products are disclosed for state-dependent read compensation. A set of non-volatile storage cells comprising a plurality of word lines. A controller is configured to perform a read operation on one or more word lines adjacent to a target word line. A controller is configured to determine a read setting for application to a target word line based on a result of a read operation on one or more word lines adjacent to the target word line. A controller is configured to perform a read operation on a target word line using a determined read setting.