3D Memory String Channel Initialization for Hot Carrier Injection
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Solution Overview
Problem
In three-dimensional (3-D) memory devices, hot carrier injection occurs in unselected strings during read operations, leading to electrical defects due to narrowed string intervals, which affects the reliability and efficiency of data retrieval.
Innovation Solution
A memory device with a controller that performs channel-initializing operations on both selected and unselected strings during read operations, specifically adjusting the channel-initializing method based on the physical location of the selected string to minimize hot carrier injection and improve read operation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of strings in the memory cell array is increased to improve integration density, then storage capacity is improved, but electrical defects occur between adjacent strings due to narrowed intervals
Solution Approach 1:
The patent divides the string group into multiple subsets (first string group, second string group, third string group) based on their spatial relationships with the selected string. This segmentation allows different initialization strategies to be applied to different groups, managing the electrical defects caused by narrow intervals while maintaining high string density.
Solution Approach 2:
The patent applies different channel initialization operations to different string groups based on their local characteristics. Strings in the first group (adjacent to selected string) receive full initialization, while strings in the second and third groups receive reduced or no initialization, optimizing reliability for each local region without uniform overhead.
2Reliability
If channel-initializing operations are performed on all unselected strings to suppress hot carrier injection, then read operation reliability is improved, but operation time is increased
Solution Approach 1:
The patent performs channel initialization on only a subset of unselected strings (first string group) that are most critical and adjacent to the selected string, rather than initializing all unselected strings. This partial action suppresses hot carrier injection where it matters most while reducing overall operation time.
Solution Approach 2:
The patent optimizes the timing and continuity of channel initialization operations by performing them during the read operation sequence rather than as separate preparatory steps. The initialization is integrated into the read workflow, maintaining continuous useful action without adding separate time overhead.
3Reliability
If channel-initializing operations are performed on adjacent unselected strings to suppress hot carrier injection, then electrical defects are reduced, but operation complexity is increased
Solution Approach 1:
The patent segments unselected strings into distinct groups (first, second, third string groups) based on their proximity and relationship to the selected string. This segmentation simplifies control by providing clear categories for applying different initialization strategies, reducing the complexity of managing hot carrier injection suppression.
Solution Approach 2:
The patent dynamically adjusts the channel initialization strategy based on the specific read operation and selected string configuration. The controller adaptively determines which string groups require initialization and to what extent, optimizing the balance between defect suppression and operational simplicity for each specific case.
Data Source
AI summary
A memory device comprises a memory cell array comprising multiple memory cells that are connected between multiple word lines, multiple bit lines, and K strings, and a controller configured to: perform, in a read operation on a first logical page of a selected physical page corresponding to a selected word line, the multiple bit lines and a selected string, a first channel-initializing operation on the selected string and first strings among unselected strings, and perform, in a read operation on a second logical page of the selected physical page, a second channel-initializing operation on the selected string and second strings among the unselected strings, the first and second strings partially overlapping each other, wherein K is a natural number equal to or greater than 2.