Vertical Memory Contact Plug Density Uniformity
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Solution Overview
Problem
Contact plugs in VNAND flash memory devices often have non-uniform density, leading to electrical failures due to insufficient contact with substrates or gate structures, resulting in low density and undesired sizes.
Innovation Solution
The implementation of additional lower contact plugs adjacent to those with low density in the peripheral region of the substrate to ensure proper contact and desired size, along with a specific configuration of gate electrodes and interlayers to enhance electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact plugs are formed in the peripheral region of the substrate, then electrical connectivity is established, but the density becomes non-uniform causing electrical failures
Solution Approach 1:
The patent applies local quality by forming additional lower contact plugs specifically in regions where density is insufficient. Instead of treating all contact plugs uniformly, the invention identifies areas with low density and adds extra contact plugs locally to achieve the desired density threshold, thereby resolving the non-uniform density issue while maintaining electrical connectivity.
2Reliability
If contact plug density is increased to ensure proper contact, then electrical reliability improves, but device complexity increases
Solution Approach 1:
The patent segments the contact plug formation process into different regions based on density requirements. Lower contact plugs are formed in the peripheral region, and additional lower contact plugs are formed specifically in areas where the density of the first lower contact plugs is insufficient. This segmentation allows targeted enhancement of contact reliability without uniformly increasing device complexity.
3Manufacturing precision
If additional lower contact plugs are formed to compensate for low density, then contact size and reliability improve, but manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by forming additional lower contact plugs in advance during the manufacturing process, specifically in regions where density is predicted or measured to be insufficient. This preliminary enhancement ensures that contact plugs achieve the desired size and density before subsequent manufacturing steps, preventing electrical failures without requiring complex post-processing corrections.
Data Source
AI summary
A vertical memory device includes a substrate including a cell region and a peripheral circuit region, gate electrodes sequentially stacked on the cell region of the substrate in a vertical direction substantially perpendicular to an upper surface of the substrate, a channel on the cell region and extending through the gate electrodes in the vertical direction, a first lower contact plug on the peripheral circuit region and extending in the vertical direction, a second lower contact plug on the peripheral circuit region adjacent to the first lower contact plug and extending in the vertical direction, and a first upper wiring electrically connected to the first lower contact plug. The first upper wiring is configured to and apply an electrical signal to the first lower contact plug. The second lower contact plug is not electrically connected to an upper wiring configured to apply an electrical signal.