SRAM Unit Slot Contact Plug Layout for Resistance Reduction
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Solution Overview
Problem
Conventional static random access memory (SRAM) devices face increased electrical resistance due to narrowed contact areas between metal-zero interconnects and slot contact plugs, and gate lines, which hinders dense transistor arrangement and efficient signal transmission.
Innovation Solution
The SRAM unit structure and layout design include strategically arranged slot contact plugs and metal-zero interconnects with reduced gaps between them, increasing contact areas and reducing electrical resistance, allowing for more dense transistor packing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of the device is reduced, then the integration density is improved, but the contact areas between metal-zero interconnects and slot contact plugs are decreased, increasing electrical resistance
Solution Approach 1:
The slot contact plug is designed to extend in the first direction beyond the metal-zero interconnect, creating an overlapping contact area. This dimensional extension transforms a point-contact into an area-contact, effectively increasing the contact area between the slot contact plug and metal-zero interconnect without increasing the overall device footprint, thereby reducing electrical resistance while maintaining high integration density
Solution Approach 2:
The layout structure is designed such that the slot contact plug position is predetermined to overlap with the metal-zero interconnect in the first direction. This preliminary positioning ensures that the contact area is maximized before any operational use, preventing resistance issues from the outset while enabling dense transistor arrangement
2Length of moving object
If the slot contact plug width is narrowed, then the device size is reduced, but the contact area between slot contact plug and metal-zero interconnect is decreased, increasing electrical resistance
Solution Approach 1:
Instead of increasing the width of the slot contact plug to increase contact area, the design extends the plug in the first direction (length dimension) to create overlap with the metal-zero interconnect. This approach increases contact area without increasing the plug width, thereby maintaining small device size while reducing electrical resistance
Solution Approach 2:
The slot contact plug has an asymmetric layout where it extends beyond the metal-zero interconnect in the first direction, creating an unequal distribution of contact areas. This asymmetric design optimizes the contact geometry to maximize effective contact area without proportionally increasing the overall plug dimensions, enabling reduced device size with maintained electrical performance
Data Source
AI summary
A static random access memory unit structure and layout structure includes two pull-up transistors, two pull-down transistors, two slot contact plugs, and two metal-zero interconnects. Each metal-zero interconnect is disposed on each slot contact plug and a gate of each pull-up transistor, in which, each slot contact plug crosses a drain of each pull-down transistor and a drain of each pull-up transistor and extends to cross an end of each metal-zero interconnect. A gap between the slot contact plugs is smaller than a gap between the metal-zero interconnects.