3D Memory Pass Word Line Compensation for Read Reliability
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Solution Overview
Problem
In three-dimensional memory devices, uneven channel formation during read operations leads to hot carrier generation due to variations in channel voltage, affecting the reliability of memory cell threshold voltages.
Innovation Solution
A memory device with a voltage generator that applies a compensation voltage more rapidly than a pass voltage to unselected word lines, ensuring uniform channel formation by controlling the rising slope of these voltages to improve read operation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pass voltage is applied to unselected word lines to form a channel, then the channel formation is enabled, but uneven channel voltage occurs leading to hot carrier generation
Solution Approach 1:
The patent applies different voltage levels to different regions of the memory device by introducing pass word lines at specific locations (e.g., upper and lower portions of the cell plug) and applying compensation voltages to these pass word lines while applying pass voltage to unselected word lines. This creates local voltage adjustments that compensate for regional variations in channel formation, ensuring uniform channel voltage across the entire cell plug and preventing hot carrier generation.
2Stability of the object's composition
If the compensation voltage rises rapidly to ensure uniform channel formation, then channel uniformity is improved, but the complexity of voltage control increases
Solution Approach 1:
The patent segments the word lines into different categories: unselected word lines receiving pass voltage and pass word lines receiving compensation voltage. The voltage generator is divided into multiple output circuits that independently control different voltage levels. This segmentation allows for simplified control of each voltage level while achieving the overall goal of uniform channel formation through coordinated voltage application.
Data Source
AI summary
A memory device and a method of operating the memory device are provided. The memory device includes memory cells located between a bit line and a source line, pass cells located between the memory cells, word lines coupled to the memory cells, pass word lines coupled to the pass cells, and a voltage generator configured to apply a read voltage to a selected word line among the word lines, a pass voltage to unselected word lines among the word lines, and a compensation voltage to the pass word lines during a read operation, wherein the voltage generator is configured to raise the compensation voltage more rapidly than the pass voltage.