Memory Device Read Reliability via Cell Group Segmentation
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Solution Overview
Problem
As memory devices with three-dimensional structures become more integrated, memory cells interfere with each other, and the narrowing of threshold voltage intervals leads to overlapping voltages, deteriorating the reliability of read operations.
Innovation Solution
A method of operating a memory device that involves programming data by distributing it across multiple memory cell groups corresponding to different drain select lines, reading memory cells from these groups, and determining threshold voltages to generate data codes based on combinations of these voltages during read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the integration density of the memory device is increased, then the storage capacity is improved, but the memory cells interfere with each other and the threshold voltage intervals narrow, causing overlap and deteriorating read operation reliability
Solution Approach 1:
The memory cells are divided into multiple groups (first memory cell group and second memory cell group) based on their connection to different drain select lines. This segmentation allows independent reading of each group, enabling the system to distinguish between overlapping threshold voltages by processing groups separately rather than as a single unified structure.
Solution Approach 2:
The drain select lines serve as intermediary elements that enable differentiation between memory cell groups. By using these select lines as mediators, the system can selectively access and read specific groups, thereby resolving the interference and threshold voltage overlap issues that would otherwise affect all cells simultaneously.
2Quantity of substance
If the number of bits of data stored in the memory device is increased, then the storage capacity is improved, but the intervals between threshold voltages of the memory cells narrow, causing overlap and deteriorating read operation reliability
Solution Approach 1:
The memory cells are segmented into groups based on drain select line connections, allowing the system to read and process threshold voltages in discrete, manageable units. This segmentation preserves measurement precision by preventing the threshold voltage intervals from becoming indistinguishable when storing multiple bits of data.
Solution Approach 2:
The patent introduces a new dimension of organization by grouping memory cells according to their drain select line connections rather than solely by threshold voltage levels. This additional organizational dimension allows the system to differentiate between cells with overlapping threshold voltages by referencing their group assignments, thereby maintaining measurement precision while increasing storage capacity.
Data Source
AI summary
The present disclosure relates to method of operating a memory device that includes programming program data by distributing the program data to a first memory cell group corresponding to a first drain select line and a second memory cell group corresponding to a second drain select line during a program operation of a selected memory block, reading memory cells included in each of the first memory cell group and the second memory cell group during a read operation of the selected memory block, and determining threshold voltages for the first memory cell group according to a read result for the first memory cell group and threshold voltages for the second memory cell group according to a read result for the second memory cell group and outputting data codes corresponding to combinations of the threshold voltages during a read operation of the selected memory block.