Memory Read Control Using Disturb Sensing for Weak Word Lines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in nonvolatile memory devices is the change in threshold voltage distribution of memory cells due to the influence of channel potential of unselected memory cell strings during read operations, which affects the performance of the read operation.
Innovation Solution
A memory device with a read operation controller that adjusts the extent of channel potential increase of unselected memory cell strings through a disturb sensing operation, allowing the read operation to be performed in a first or second mode based on the threshold voltage change of dummy memory cells, thereby reducing the disturbance phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the channel potential of unselected memory cell strings is increased to improve read operation performance, then the read operation performance is improved, but the threshold voltage distribution of memory cells changes due to disturbance
Solution Approach 1:
The patent applies dynamics by making the read operation mode selectable between first and second modes based on disturb sensing results. The read operation controller dynamically chooses the appropriate mode depending on the measured threshold voltage change of dummy memory cells, allowing the system to adapt between performance optimization and disturbance mitigation
Solution Approach 2:
The patent implements feedback through the disturb sensing operation that measures the threshold voltage change of dummy memory cells. This measurement feeds back to the read operation controller, which then determines whether to perform the read operation in the first or second mode, creating a closed-loop control system that adjusts read operations based on actual disturbance levels
2Stability of the object's composition
If the magnitude of channel potential increase is controlled to reduce threshold voltage distribution change, then the threshold voltage distribution stability is improved, but the read operation performance may be limited
Solution Approach 1:
The patent applies parameter changes by switching between two distinct read operation modes with different channel potential characteristics. The first mode uses a smaller channel potential increase to maintain stability, while the second mode uses a larger channel potential increase to improve performance, allowing the system to adjust parameters based on disturb sensing results
Data Source
AI summary
A memory device includes: a plurality of memory cell strings including a plurality of memory cells connected to a plurality of word lines; a peripheral circuit for performing a read operation that reads data stored selected memory cells connected to a selected word line among the plurality of word lines; and a read operation controller for controlling the peripheral circuit to perform the read operation in a first mode or a second mode, based on a result obtained by performing a disturb sensing operation that identifies a degree to which a threshold voltage of dummy memory cells connected to a dummy word line is changed when the selected word line is included in weak word line information.