Buried Rail Transistor Layout for Higher Cell Integration
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Solution Overview
Problem
As semiconductor manufacturing processes increase integration levels, the existing technologies face challenges in efficiently arranging transistors to minimize active patterns and enhance integration density without compromising performance.
Innovation Solution
The semiconductor device incorporates a design where two pull-up transistors are formed on one active pattern in a cell region, with active cuts between them, and similarly for pull-down transistors, allowing for horizontal alignment across adjacent cell regions to reduce active pattern count and increase integration density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional transistor arrangement methods are used, then each transistor requires its own separate active pattern, but this increases the number of active patterns and reduces integration density
Solution Approach 1:
The patent merges multiple transistor channels into a single shared active pattern. Specifically, multiple pull-up transistors and pull-down transistors are configured to share common source/drain regions and active patterns, thereby reducing the total number of active patterns required while maintaining all necessary transistor functions. This combining approach directly reduces the quantity of active patterns and enhances integration density.
Solution Approach 2:
The patent implements multi-functionality by designing active patterns that serve multiple purposes simultaneously. A single active pattern functions as the channel for multiple transistors, and source/drain regions serve as shared components for adjacent transistors. This universal usage of active patterns and shared regions allows the same structural elements to perform multiple transistor functions, thereby reducing the overall count of active patterns needed in the circuit.
2Area of stationary object
If more active patterns are used to accommodate all transistors, then transistor functionality is maintained, but the cell region size increases and integration level decreases
Solution Approach 1:
The patent combines multiple transistor functions into a reduced number of active patterns within the same cell region. By sharing active patterns and source/drain regions among multiple transistors, the overall area occupied by active patterns is minimized, allowing higher integration levels without expanding the cell region footprint.
Solution Approach 2:
The patent utilizes vertical stacking and three-dimensional arrangement of transistors within the planar active pattern area. Multiple channels are formed vertically or in stacked configurations within the same footprint, effectively using the vertical dimension to increase integration density without increasing the horizontal cell region area.
3Productivity
If active patterns are reduced to increase integration density, then more transistors can be integrated, but transistor performance may be compromised
Solution Approach 1:
The patent segments the shared active pattern into multiple distinct channels, each serving specific transistor functions. Within the shared active pattern, separate channels are defined for pull-up transistors and pull-down transistors, ensuring that each transistor maintains its electrical independence and performance characteristics while sharing the physical active pattern infrastructure.
Solution Approach 2:
The patent applies local quality by providing transistor-specific features within the shared active pattern region. Each channel within the shared active pattern has locally optimized characteristics such as channel width, length, and doping profiles tailored to the specific transistor performance requirements, ensuring that individual transistor performance is maintained despite the shared structure.
Data Source
AI summary
A semiconductor device including: first and second cell regions; a substrate including first and second surfaces; first to third active patterns extending in a first horizontal direction in the first cell region, the first to third active patterns spaced apart from each other in a second horizontal direction; a fourth active pattern extending in the first horizontal direction in the second cell region, the fourth active pattern is aligned with the second active pattern in the first horizontal direction; an active cut separating the second and fourth active patterns; a source/drain region on the second active pattern; a buried rail extending in the first horizontal direction on the second surface of the substrate, the first buried rail overlaps each of the second and fourth active patterns in a vertical direction; and a source/drain contact penetrating the substrate and second active pattern and connecting the source/drain region to the buried rail.