3D NAND Memory Programming by Coupling-Offset State Grouping
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Solution Overview
Problem
Existing technologies face challenges in efficiently programming and accurately reading multi-level memory cells in 3D NAND memory devices due to increased programming time and reduced read margins as the number of bits stored in each cell increases.
Innovation Solution
A method is introduced that divides target programmed states into groups based on coupling offsets, performs initial and secondary program operations, and uses verification operations with specific voltages to ensure accurate programming and reading of memory cells, particularly in triple-level and quad-level cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-level programming is used to increase storage capacity in memory cells, then storage density is improved, but programming time increases
Solution Approach 1:
The patent segments the programming process into two distinct phases: a first program operation that programs memory cells to intermediate states, and a second program operation that programs subset groups to final target states. This segmentation allows parallel processing of different cell groups, reducing overall programming time while maintaining multi-level storage capacity.
Solution Approach 2:
The first program operation performs preliminary programming of all memory cells to intermediate states before the second program operation refines them to final target states. This preliminary action enables subsequent operations to focus only on specific subsets of cells, improving efficiency and reducing total programming time.
2Quantity of substance
If multi-level programming is used to increase storage capacity in memory cells, then storage density is improved, but read accuracy deteriorates
Solution Approach 1:
The patent segments target programmed states into multiple groups (first group, second group, third group, etc.) with distinct coupling offset characteristics. This segmentation allows for group-specific verification operations using tailored verification voltages, improving read accuracy by accounting for differential coupling effects in multi-level cells.
Solution Approach 2:
The patent applies local quality by using different verification voltages for different groups of programmed states. Each group receives verification tailored to its specific coupling offset characteristics, ensuring accurate reading despite the complexity introduced by multi-level programming.
3Device complexity
If coupling offsets are not considered in programming, then programming process is simpler, but read accuracy deteriorates
Solution Approach 1:
The patent segments programmed states into groups based on their coupling offset characteristics (first group with first coupling offsets, second group with second coupling offsets, etc.). This segmentation manages complexity by organizing states into manageable groups while enabling accurate reading through group-specific verification voltages.
Solution Approach 2:
The patent changes verification parameters (voltages) based on the group to which programmed states belong. By adjusting verification voltages according to coupling offset characteristics of different groups, the patent maintains read accuracy without requiring complete redesign of the programming process.
Data Source
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AI summary
The present disclosure provides a programming method, a memory device and a memory system. The method includes, based on coupling offsets, dividing target programmed states into N groups, each group corresponding to a different first programmed state, wherein an i-th group has Ki number of different target programmed states and corresponds to an i-th first programmed state. At least two groups of target programmed states have two different numbers of target programmed states. The method also includes performing a first program operation to program memory cells to respective first programmed states; and performing a second program operation to program an i-th group of memory cells at the i-th first programmed state to Ki number of different target programmed states.