SRAM Unit Cell Layout with Segmented Gates and Conductive Lines
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Solution Overview
Problem
Existing semiconductor devices face challenges in improving circuit performance and reliability due to issues such as metal filling problems, increased routing resistance, parasitic capacitance, short circuits, leakage, alignment margin reduction, and decreased packing density, particularly in SRAM unit cells with narrow active patterns and shrinking metal wiring.
Innovation Solution
A semiconductor device design featuring a conductive line structure that connects gate electrodes, with SRAM unit cells comprising cross-coupled inverters and pass transistors, and conductive lines that intersect and separate gate electrodes, enhancing layout flexibility and packing density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-channel transistor with narrow active pattern width is used for short channel control, then device performance is improved, but alignment margin is reduced and device pitch increases
Solution Approach 1:
The gate electrode is divided into multiple segments separated by conductive line structures. This segmentation allows the gate to be split into distinct regions that can be independently controlled, enabling narrow active pattern width for short channel control while maintaining sufficient alignment margin through the separating conductive lines.
2Productivity
If metal wiring is shrunk to smaller feature size to improve circuit routing density, then routing density is improved, but metal filling problem occurs and diffusion barrier metal layer is needed
Solution Approach 1:
A diffusion barrier metal layer is introduced as an intermediary between the metal wiring and the semiconductor substrate. This barrier layer enables smaller feature sizes and improved routing density while preventing metal diffusion and filling problems that would otherwise occur at tighter pitches.
3Reliability
If diffusion barrier metal layer is added to prevent metal diffusion, then reliability is improved, but metal line and metal plug sizes are reduced
Solution Approach 1:
The solution moves from horizontal scaling to vertical stacking by introducing the diffusion barrier metal layer as a separate vertical layer. This allows the metal wiring to maintain its functional size while the barrier layer provides the necessary diffusion prevention in a different dimensional space.
4Productivity
If device size is reduced to increase packing density, then packing density is improved, but routing resistance increases and parasitic capacitance increases
Solution Approach 1:
The conductive line structures extend in the vertical dimension, allowing gate electrodes to be separated and connected through multiple levels. This vertical arrangement enables reduced device footprint and increased packing density while maintaining adequate routing dimensions to control resistance and capacitance.
Data Source
AI summary
A semiconductor device includes a substrate having first and second surfaces, first to third conductive line structures disposed on the first surface, extending in a first direction, and spaced apart from each other in a second direction, and a SRAM unit cell disposed on the first surface, and including first and second inverters connected to each other, a first pass transistor connected to the first inverter, a second pass transistor connected to the second inverter, a first gate electrode included in the first inverter, and a second gate electrode included in the first pass transistor, the first inverter and the first pass transistor are disposed between the first and third conductive line structures, the second inverter and the second pass transistor are disposed between the second and third conductive line structures, and the first and second gate electrodes are disposed between the first and third conductive line structures.