Adaptive Control for Multilayered Nonvolatile Memory
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Solution Overview
Problem
Multilayered nonvolatile semiconductor memory devices face challenges in maintaining optimized operating conditions due to varying threshold voltage distribution profiles between layers, leading to inefficiencies in programming, reading, and erasing processes.
Innovation Solution
Implementing a control scheme that divides memory cell arrays into groups with adaptive control parameters stored in a look-up matrix, allowing for optimized program, read, and erase conditions based on the characteristics of each group, including incremental step pulse programming, voltage levels, and timing, which are responsive to structural and electronic test results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single control parameter set is used for all memory layers, then device complexity is reduced, but manufacturing precision deteriorates due to varying threshold voltage distributions across layers
Solution Approach 1:
The memory device is divided into multiple layers, each with its own control parameter set stored in separate look-up tables. This segmentation allows each layer to be independently optimized for its specific threshold voltage distribution characteristics, resolving the contradiction between simplified control structure and manufacturing precision.
Solution Approach 2:
Each memory layer is assigned customized control parameters (program voltage, read voltage, erase voltage, timing) tailored to its local threshold voltage distribution. This local quality approach ensures optimal performance for each layer while maintaining overall device functionality.
2Manufacturing precision
If adaptive control parameters are implemented for each memory layer, then manufacturing precision is improved, but device complexity increases due to multiple look-up tables and control structures
Solution Approach 1:
The control circuit is designed with universal look-up table structures that can store and retrieve control parameters for multiple layers. This multi-functionality allows the same control architecture to serve all layers, reducing overall device complexity while maintaining the ability to provide layer-specific optimized parameters.
Solution Approach 2:
Each memory layer's control parameters are automatically selected and applied based on the layer identifier, allowing the control circuit to self-configure for each layer without external intervention. This self-service mechanism simplifies the control structure by eliminating manual configuration complexity.
3Productivity
If layer-specific control parameters are used, then productivity is improved through optimized operations, but ease of operation deteriorates due to complex parameter management
Solution Approach 1:
The control circuit automatically retrieves and applies the appropriate control parameters for each layer based on layer identification signals, eliminating the need for manual parameter management. This self-service approach maintains ease of operation while enabling layer-specific optimization for improved productivity.
Solution Approach 2:
The control circuit uses feedback from layer identification and operation status to automatically select and adjust control parameters, ensuring optimal performance without requiring complex manual intervention. This feedback mechanism simplifies operation while maintaining high productivity.
Data Source
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.