Memory Device Programming with Split Channels for Threshold Control
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Solution Overview
Problem
The high integration of memory cells in three-dimensional devices leads to a coupling effect, causing changes in the threshold voltage distribution, which affects the performance and reliability of the memory device.
Innovation Solution
A method of operating a memory device that includes performing separate program operations on different channel regions using distinct verify voltages, identifying and correcting memory cells with suboptimal threshold voltages through additional program operations, and applying specific voltages to achieve targeted threshold distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are highly integrated in three-dimensional devices, then the integration degree of memory cells increases, but the coupling effect between memory cells causes changes in threshold voltage distribution
Solution Approach 1:
The patent divides the channel hole into multiple channel regions using cutting structures, which separates memory cells into different groups. This segmentation reduces the coupling effect between adjacent memory cells while maintaining high integration density, thereby preserving threshold voltage distribution reliability despite increased integration degree.
Solution Approach 2:
The patent applies different verify voltages to different channel regions during programming operations. By tailoring the verify voltage to each specific channel region, the method compensates for local variations in threshold voltage caused by coupling effects, ensuring reliable threshold voltage distribution across the highly integrated memory structure.
2Reliability
If separate program operations are performed on different channel regions with distinct verify voltages, then the threshold voltage distribution is improved, but the programming complexity increases
Solution Approach 1:
The patent segments the programming process into multiple operations targeting different channel regions. By organizing the complexity into structured segments with clear objectives, the method manages programming complexity systematically while achieving improved threshold voltage distribution through region-specific verify voltages.
Solution Approach 2:
The patent incorporates verify operations that provide feedback on the programming status of memory cells in each channel region. This feedback mechanism allows the system to adjust subsequent programming operations to achieve the desired threshold voltage distribution, managing complexity through intelligent control rather than brute-force programming.
3Reliability
If additional program operations are performed on memory cells with suboptimal threshold voltages, then the threshold voltage distribution is improved, but the programming time increases
Solution Approach 1:
The patent performs preliminary verification operations during the programming process to identify memory cells with suboptimal threshold voltages before completing the programming sequence. By detecting these cells early, the system can apply additional programming only where necessary, improving overall threshold voltage distribution without unnecessarily extending programming time for all cells.
Solution Approach 2:
The patent applies additional programming operations selectively to only those memory cells that require correction, rather than re-programming all cells. This partial action approach improves threshold voltage distribution for problematic cells while minimizing the overall time penalty, avoiding excessive programming of cells that are already within acceptable parameters.
Data Source
AI summary
A method of operating a memory device includes performing a first program operation on first memory cells connected to a first channel region among a plurality of channel regions formed by separating one channel hole into the plurality of channel regions, based on a first verify voltage. The method also includes performing a second program operation on second memory cells connected to a second channel region among the plurality of channel regions, based on a second verify voltage. The method further includes determining third memory cells having a threshold voltage lower than a target threshold voltage distribution among the first memory cells while performing the second program operation. The method additionally includes performing a third program operation on the third memory cells.