Nonvolatile Memory Cell Programming Optimization
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Solution Overview
Problem
Conventional nonvolatile memory devices face challenges in optimizing programming time and reliability due to differences in threshold voltage distributions between even-numbered and odd-numbered memory cells, leading to suboptimal sensing times and performance degradation.
Innovation Solution
A nonvolatile memory device that determines the structural position of memory cells and adjusts operating conditions, such as wordline and bitline voltages, based on threshold voltage distributions to optimize programming and sensing operations for both even-numbered and odd-numbered cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If program operating conditions are determined from total threshold voltage distribution irrespective of even-numbered or odd-numbered cells, then device complexity is reduced, but programming time increases and reliability deteriorates
Solution Approach 1:
The patent segments the memory cell population into even-numbered cells and odd-numbered cells based on their structural positions in the cell array. Separate program operating conditions (voltages, pulse widths) are established for each segment according to their respective threshold voltage distributions, rather than using a single unified set of conditions for all cells.
Solution Approach 2:
The patent applies local quality by tailoring program operating conditions to the specific characteristics of each cell segment. Even-numbered cells receive optimized conditions suited to their threshold voltage distribution, while odd-numbered cells receive different optimized conditions matched to their distribution, thereby improving overall programming efficiency and reliability.
2Ease of operation
If program operating conditions are determined from total threshold voltage distribution, then ease of operation is improved, but programming efficiency deteriorates
Solution Approach 1:
The patent introduces dynamic control of program operating conditions based on the structural position of memory cells. The control logic automatically selects appropriate program parameters (voltages, pulse widths) according to whether even-numbered or odd-numbered cells are being programmed, enabling adaptive optimization without manual intervention.
Solution Approach 2:
The patent changes key program parameters including pulse width, voltage level, and current based on the cell segment being programmed. By adjusting these parameters according to the specific threshold voltage distributions of even and odd-numbered cells, the system achieves optimized programming efficiency for each group.
3Device complexity
If the same sensing time is used for both even-numbered and odd-numbered bitlines, then device complexity is reduced, but read/verify characteristics deteriorate
Solution Approach 1:
The patent segments the sensing operation into separate time windows for even-numbered bitlines and odd-numbered bitlines. By determining sensing times independently for each segment based on their respective RC time constants and threshold voltage distributions, the system optimizes read and verify operations for each bitline group.
Solution Approach 2:
The patent applies local quality by assigning different sensing times to even and odd-numbered bitlines according to their specific electrical characteristics. This localized optimization ensures that each bitline segment operates with sensing parameters matched to its unique RC time constant and threshold voltage distribution, improving overall read/verify reliability.
Data Source
AI summary
Provided are a nonvolatile memory device and a driving method thereof. In the method of driving a nonvolatile memory device, a structural shape and position of a memory cell to be driven is determined, and then the memory cell is driven with an optimized operating condition according to a distribution of the memory cell using a determination result.