Dummy Devices for Semiconductor Edge Effect Resolution
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Solution Overview
Problem
In semiconductor integrated circuit manufacturing, edge effects and process uniformity issues arise due to the separation of design and manufacturing processes, leading to yield loss and performance variability, particularly in advanced technologies like 65 nm, 40 nm, and 28 nm nodes, where contact patterning and diffusion region irregularities cause challenges.
Innovation Solution
The implementation of dummy devices and structures, such as polysilicon lines and transistors, are used to address edge effects and diffusion region irregularities by sharing diffusion regions with edge devices, allowing for optimized design rules that include additional dummy polysilicon structures next to edge gate structures and between transistors with different gate lengths, thereby ensuring process uniformity and reducing real estate requirements on the chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dummy devices and structures are added to address edge effects and diffusion region irregularities, then manufacturing precision and yield are improved, but device complexity and layout area increase
Solution Approach 1:
The patent uses dummy devices that replicate the structure and diffusion regions of actual devices. These dummy copies are placed adjacent to edge devices to provide the necessary process uniformity without requiring complex modifications to the actual device design. The dummy structures serve as templates that can be systematically replicated across the layout.
Solution Approach 2:
Dummy devices act as intermediary structures between the manufacturing process requirements and the actual functional devices. They mediate the edge effects by providing intermediate diffusion regions that buffer the process variations, thereby protecting the actual devices from manufacturing precision issues without directly modifying the device design.
2Manufacturing precision
If dummy devices are placed next to edge devices to resolve edge effects, then process uniformity improves, but chip real estate increases
Solution Approach 1:
The patent merges the dummy device diffusion regions with the actual device diffusion regions by sharing common diffusion structures. This integration allows the dummy devices to provide process uniformity benefits while utilizing the same diffusion region space, thereby reducing the additional area required compared to completely separate dummy structures.
Solution Approach 2:
The patent optimizes the placement and configuration of dummy devices in the layout space by utilizing available areas efficiently. Dummy devices are positioned to share diffusion regions and utilize whitespace areas, transforming the two-dimensional layout problem into a more efficient spatial arrangement that minimizes area overhead.
3Reliability
If additional dummy polysilicon structures are added next to edge gate structures, then edge effect issues are resolved, but manufacturing complexity increases
Solution Approach 1:
The dummy polysilicon structures are incorporated into the layout design phase before manufacturing. By pre-placing these dummy structures in the design, the manufacturing process follows a standardized pattern that simplifies production. The dummy structures are created using the same polysilicon deposition and patterning processes as the actual devices, requiring no additional manufacturing steps.
Data Source
AI summary
A method of fabricating an integrated circuit includes identifying an edge device of a plurality of devices, the plurality of devices being part of a first layout including gate structures and diffusion regions, modifying the first layout resulting in a second layout, and fabricating the integrated circuit based on the second layout. Modifying the first layout resulting in the second layout includes adding a dummy device next to the edge device, the dummy device and the edge device having a shared diffusion region, adding a dummy gate structure next to the dummy device, extending the shared diffusion region to at least the dummy device, and performing a design rule check on the second layout. The performing the design rule check considers a gate structure of the dummy device as one of two dummy gate structures next to the edge device.