Semiconductor Dummy Region Layout for Across-Chip Uniformity
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Solution Overview
Problem
Existing semiconductor fabrication technologies face challenges in achieving across-chip uniformity and electrical performance due to physical variations during the manufacturing process, particularly in the integration of multi-gate devices like FinFETs and GAA transistors, leading to issues with gate-channel coupling and short-channel effects.
Innovation Solution
The introduction of dummy regions in semiconductor structures, which are designed to mitigate loading effects during fabrication processes, by including dummy transistors that are not interconnected and are formed using similar manufacturing processes as functional devices, with carefully controlled layouts to converge the critical dimension distribution of epitaxial source/drain features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-gate devices like FinFETs and GAA transistors are introduced to improve gate control, then gate-channel coupling is improved and off-state current is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the semiconductor chip into multiple regions with different device densities. Functional device regions containing multi-gate devices are separated from dummy device regions, allowing the complex multi-gate structures to be concentrated in specific areas while simpler planar devices populate other areas. This segmentation enables manufacturing processes to be optimized for each region type, reducing overall manufacturing difficulty while maintaining the reliability benefits of multi-gate devices where needed.
Solution Approach 2:
The patent applies different device structures to different locations on the chip. Multi-gate devices with superior gate control are placed in regions requiring high performance, while planar devices are used in regions where complexity reduction is prioritized. The dummy device regions are strategically positioned to provide loading effects that benefit functional regions locally, without requiring the entire chip to use complex multi-gate structures.
2Productivity
If device density is increased to improve functional density, then more devices fit per chip area, but manufacturing precision and across-chip uniformity deteriorate due to physical variations
Solution Approach 1:
The patent creates homogeneous regions of devices with similar characteristics and densities. By organizing devices into functional regions and dummy device regions with consistent device types and spacing, the manufacturing process experiences fewer variations across the chip. This homogeneity allows for better process control and improved across-chip uniformity, as each region can be manufactured with optimized parameters tailored to its specific device characteristics.
3Manufacturing precision
If dummy regions are added to mitigate loading effects, then across-chip uniformity improves, but chip area and device complexity increase
Solution Approach 1:
The patent uses dummy devices that are copies or replicas of functional devices, placed in dummy device regions. These dummy devices replicate the physical characteristics and loading effects of functional devices without needing to be electrically connected. By copying the structural features of functional devices, the dummy regions provide the necessary loading effects to improve across-chip uniformity while maintaining area efficiency, as the copies can be optimally positioned to maximize their beneficial effects with minimal space consumption.
Data Source
AI summary
A semiconductor structure and a method of fabricating thereof including a substrate having a device region and a dummy region. The device region includes a number of N-type device cells having a plurality of operational N-type transistors and a number of P-type device cells having a plurality of operational P-type transistors. The dummy region includes a number of N-type dummy cells having a plurality of non-operational N-type transistors and a number of P-type dummy cells having a plurality of non-operational P-type transistors, and a total number of the N-type device cells and P-type device cells is equal to a total number of the N-type dummy cells and P-type dummy cells.