Nonvolatile Memory Read Parameter Adjustment for Degradation
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Solution Overview
Problem
Nonvolatile memory devices face challenges in reducing error bits during data processing and accurately identifying the state of memory cells, particularly due to degradation over time, which affects the reliability of read operations.
Innovation Solution
A nonvolatile memory device with a page buffer and control logic that performs multiple sensing operations to identify the state of memory cells, using a page buffer with latch sets to store data and determine optimal read parameters based on degradation levels, allowing for the selection of desired data with minimized error bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensing operations are performed to identify memory cell states, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary sensing operations before the actual read operation to detect degradation levels and determine optimal read parameters. By conducting these preparatory sensing operations in advance, the system identifies memory cell states and adjusts read parameters proactively, improving measurement precision without adding complexity to the critical read path.
Solution Approach 2:
The memory device performs self-diagnosis through sensing operations to detect its own degradation level. The control logic automatically adjusts read parameters based on detected degradation, enabling the system to self-optimize without external intervention. This self-service mechanism improves measurement precision while keeping the control architecture relatively simple.
2Reliability
If read parameters are adjusted based on degradation level, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic adjustment of read parameters based on detected degradation levels. The control logic selects from multiple predefined read parameter sets (first, second, third read parameters) corresponding to different degradation stages. This dynamic adaptation improves reliability by matching read parameters to actual memory cell conditions without requiring complex real-time parameter synthesis.
Solution Approach 2:
The system changes read parameters (such as read voltage levels or sensing thresholds) based on detected degradation levels. By preparing multiple parameter sets in advance and selecting the appropriate set based on degradation detection, the system improves reliability through parameter adaptation while avoiding the complexity of real-time parameter calculation and synthesis.
3Manufacturing precision
If error exclusion range is defined based on count sections, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the page buffer into multiple count sections and defines error exclusion ranges for each section based on count values. This segmentation allows precise error handling tailored to different regions of the memory array, improving manufacturing precision by addressing local variations. The modular approach to error exclusion keeps control logic manageable through structured division.
Solution Approach 2:
The system applies different error exclusion ranges to different count sections based on their specific characteristics. By tailoring error exclusion parameters to local conditions in different sections rather than using a uniform approach, the system improves manufacturing precision while maintaining relatively simple control logic through localized rather than global complexity.
Data Source
AI summary
A nonvolatile memory device may include a page buffer including a plurality of latch sets that latch each page datum of selected memory cells among a plurality of memory cells according to each of read signal sets including at least one read signal, and a control logic configured to detect a degradation level of the memory cells and determine a read parameter applied to at least one of the read signal sets based on the detected degradation level.