Nonvolatile Memory Device Coupling Noise Reduction
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Solution Overview
Problem
Conventional nonvolatile memory devices face challenges in minimizing coupling noise between bit lines, especially as cell size decreases, affecting the accuracy of program and verification operations.
Innovation Solution
The implementation of a nonvolatile memory device with a current source and memory cell string, where the programming status of memory cells is determined by the voltage of a first node, and a method involving a current supply unit, bit line switch, and sense nodes to selectively couple the memory cell string, allowing for precise threshold voltage measurement and reduced coupling noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional sequential program and verification operations are performed on even and odd pages, then the coupling noise between bit lines can be minimized, but the sensing accuracy deteriorates when cell size is reduced
Solution Approach 1:
The patent introduces a current source as an intermediary element that is selectively coupled to the memory cell string through a bit line switch. This current source provides a controlled current path that isolates the sensing operation from coupling noise on other bit lines, thereby maintaining sensing accuracy even when cell size is reduced and conventional noise minimization methods become ineffective
2Quantity of substance
If cell size is reduced to increase memory density, then the memory capacity is improved, but the coupling noise between bit lines increases affecting verification operation
Solution Approach 1:
The bit line switch acts as an intermediary that selectively connects the current source to the target memory cell string during verification operations. This selective coupling ensures that current flows only through the intended cell string, preventing noise coupling from adjacent bit lines and maintaining signal integrity despite reduced cell spacing
Solution Approach 2:
The patent changes the operational parameters by using a current source instead of voltage-based sensing, and by dynamically controlling the coupling state through the bit line switch. This parameter change allows the system to maintain high sensing accuracy despite the physical constraint of reduced cell size
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the verification operation by accurately determining the programming state of memory cells with reduced noise, improving sensing accuracy and operational efficiency.
Implementation Method 1
determining a voltage supplied to a node between the current supply unit and the memory cell string, according to the amount of current supplied by the current supply unit
Data Source
AI summary
A nonvolatile memory device includes a first node, a current source configured to have a current value determined according to a voltage supplied to the first node, and a memory cell string coupled to the first node, the memory cell string including at least one memory cell. Whether a memory cell included in the memory cell string has been programmed is determined based on the voltage supplied to the first node.