Adaptive Control for Multilayered Nonvolatile Memory
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Solution Overview
Problem
Multilayered nonvolatile semiconductor memory devices face challenges in maintaining optimal threshold voltage distribution profiles across different layers, leading to wider distribution profiles and varying characteristics between memory cells in different layers.
Innovation Solution
Implementing an adaptive control scheme that divides memory cell arrays into predetermined block groups, using a lookup matrix to store characteristic information and a state machine to control operating conditions based on this data, optimizing program, read, and erase operations by adjusting voltages and timing in incremental steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multilayered memory structure is used to increase storage capacity, then storage density is improved, but threshold voltage distribution becomes wider and cell characteristics vary between layers
Solution Approach 1:
The memory cell array is divided into multiple block groups, with each block group containing blocks from different layers. This segmentation allows independent optimization of operating parameters for each block group, enabling precise control of threshold voltage distribution while maintaining high storage density through the multilayer structure.
Solution Approach 2:
Different operating conditions (voltages, timing parameters) are applied to different block groups based on their specific layer composition and characteristics. This local quality approach ensures that each block group operates under optimal conditions for its specific configuration, maintaining narrow threshold voltage distribution across all layers simultaneously.
2Manufacturing precision
If adaptive control scheme is implemented to optimize operating conditions, then threshold voltage distribution is maintained, but device complexity increases
Solution Approach 1:
A lookup matrix is pre-populated with optimal operating conditions for different block group configurations during manufacturing or initialization. During operation, the appropriate parameters are quickly retrieved from this pre-computed table, avoiding complex real-time calculations and reducing control logic complexity while maintaining precise threshold voltage control.
Solution Approach 2:
The lookup matrix acts as an intermediary between the control logic and the memory arrays, storing pre-determined optimal parameters. This intermediary structure simplifies the control logic by replacing complex real-time optimization algorithms with straightforward table lookups, reducing device complexity while maintaining control precision.
Data Source
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AI summary
A method and device for adaptive control of multilayered nonvolatile semiconductor memory are provided, the device including memory cells organized into groups and a control circuit having a look-up matrix for providing control parameters for each of the groups, where characteristics of each group are stored in the look-up matrix, and the control parameters for each group are responsive to the stored characteristics for that group; the method including organizing memory cells into groups, storing characteristics for each group in a look-up matrix, providing control parameters for each of the groups, where the control parameters for each group are responsive to its stored characteristics, and driving each memory cell in accordance with its provided control parameters.