Local Metal Density Layout for Lower Interconnect Capacitance
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Solution Overview
Problem
Integrated circuit designs face challenges in balancing electrical performance and fabrication process limitations due to excess metal lines, which can cause RC delays and structural degradation.
Innovation Solution
A method is developed to analyze circuit layouts during the post-tape-in phase, dividing the circuit into regions to determine line density, identifying essential metal lines, and converting redundant metal lines into dummy structures to maintain minimum line density requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess metal lines are added to mitigate metal density concerns, then fabrication process reliability is improved, but RC delays and parasitic capacitance increase
Solution Approach 1:
The patent applies local quality by differentiating between essential metal lines and redundant metal lines in different regions of the circuit layout. Essential lines are preserved to maintain fabrication reliability, while redundant lines are converted to dummy structures with optimized density to minimize RC delays and parasitic capacitance in specific locations
Solution Approach 2:
The patent changes the density parameter of metal lines locally by converting redundant lines to dummy structures with controlled density values. This allows the metal density to be adjusted in specific regions to meet fabrication requirements while minimizing the harmful effects of excess metal in other regions
2Object-affected harmful factors
If redundant metal lines are removed to reduce RC delays, then circuit performance is improved, but fabrication process issues arise
Solution Approach 1:
The patent applies local quality by selectively converting only redundant metal lines to dummy structures while preserving essential metal lines. This localized transformation reduces RC delays in specific regions without compromising the overall metal density required for fabrication reliability
Solution Approach 2:
The patent converts harmful redundant metal lines into beneficial dummy structures that maintain minimum metal density requirements for fabrication while minimizing RC delays. The redundant lines are transformed into controlled dummy structures with optimized density, turning a harmful element into a beneficial one
3Object-affected harmful factors
If arbitrary removal of excess metal lines is performed, then parasitic capacitance is reduced, but process issues and defects increase
Solution Approach 1:
The patent applies local quality by performing selective conversion of redundant metal lines to dummy structures based on their electrical characteristics and location. This localized approach reduces parasitic capacitance in critical regions while maintaining appropriate metal density in regions where it is essential for defect-free fabrication
Solution Approach 2:
The patent performs preliminary analysis to identify essential versus redundant metal lines before conversion. This preliminary action ensures that only appropriate lines are converted to dummy structures, preventing fabrication defects while reducing parasitic capacitance
Data Source
AI summary
An integrated circuit structure includes a plurality of interconnect lines and a plurality of dummy lines that are co-planar with the plurality of interconnect lines, where a ratio of line length to end-to-end spacing of the dummy lines varies inversely with a density of the interconnect lines within each of a plurality of regions. The regions are of approximately equal area within a rectangular grid array.