Bidirectional Word Line Driving in 3D Memory Arrays
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Solution Overview
Problem
In three-dimensional stack structures of semiconductor devices, signal interference and increased coupling capacitance occur between adjacent word lines due to alternating directions of driving voltages applied to vertically stacked word lines.
Innovation Solution
The memory device is designed with word lines grouped into two directions, where one group receives driving voltage at one end portion and another group at the opposite end portion, reducing signal interference and coupling capacitance by driving adjacent word lines in the same direction within each group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If word lines are vertically stacked in a three-dimensional structure, then integration density is improved, but signal interference and coupling capacitance between adjacent word lines increase
Solution Approach 1:
The patent divides the word line array into two separate groups: first word lines connected to first word line pads and second word lines connected to second word line pads. This segmentation allows adjacent word lines within each group to be driven in the same direction, reducing signal interference and coupling capacitance while maintaining high integration density through vertical stacking
Solution Approach 2:
The patent introduces a new dimension to the conventional single-direction word line driving approach by implementing bidirectional driving: first word lines are driven from first end portions while second word lines are driven from second end portions. This dimensional change in the driving scheme reduces electromagnetic interference between adjacent vertically-stacked word lines
2Device complexity
If driving voltage is applied to all word lines in the same direction, then circuit design is simplified, but signal interference between adjacent word lines increases
Solution Approach 1:
The patent segments the word line driving circuitry into two independent sets: first word line pads connected to first word lines and second word line pads connected to second word lines. This segmentation enables differentiated driving directions for different word line groups, reducing signal interference without significantly increasing overall circuit complexity
Solution Approach 2:
Instead of driving all word lines from one end (conventional approach), the patent inverts the approach by driving alternating word lines from opposite ends. First word lines are driven from first end portions while second word lines are driven from second end portions, thereby reducing coupling capacitance and signal interference between adjacent vertically-stacked word lines
Data Source
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AI summary
A memory device includes a plurality of word lines stacked in a vertical direction on a semiconductor substrate and including word line pads extending in a first direction, and a row decoder configured to provide a driving voltage to the plurality of word lines, wherein first word line pads provided at first end portions of a plurality of first word lines sequentially stacked among the plurality of word lines are connected to the row decoder, and second word line pads provided at second end portions of a plurality of second word lines sequentially stacked among the plurality of word lines are connected to the row decoder.