Off-Grid Routing Structures Using Self-Aligned Double Patterning
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Solution Overview
Problem
Traditional methods for fabricating off-grid metal structures in integrated circuits using SADP technology result in inefficient use of IC layouts, requiring multiple tracks for a single off-grid metal island, which limits layout flexibility and performance.
Innovation Solution
A method involving the use of mandrels and non-mandrel regions with specific widths and spacers to position metal routes on vertically aligned tracks, allowing off-track metal structures to be formed without using additional tracks, thereby optimizing layout efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional methods are used to fabricate off-grid metal structures, then metal routes are placed on pre-determined gridded routing tracks, but this results in inefficient use of IC layouts requiring four tracks for a single off-grid metal island
Solution Approach 1:
The patent extends metal routes from confined grid tracks into the spaces between tracks by forming mandrels that span across multiple track regions. This dimensional extension allows off-grid metal structures to access regions previously unavailable, reducing the number of tracks needed from four to two while maintaining manufacturability through controlled mandrel formation and spacing.
2Adaptability or versatility
If off-grid routing is implemented using traditional methods, then flexible pin access and redundant via insertion are enabled, but this requires additional tracks increasing layout complexity
Solution Approach 1:
The patent merges the functions of multiple separate tracks by forming continuous mandrels that span across what would traditionally require four separate track regions. This consolidation maintains the flexibility for pin access and redundant via insertion while reducing layout complexity by eliminating two entire tracks from the design.
Solution Approach 2:
The extended mandrel structures serve multiple functions simultaneously: they provide routing paths, enable off-grid access points, support redundant via insertion, and maintain structural integrity across track boundaries. This multi-functionality eliminates the need for dedicated separate structures for each function, simplifying the overall layout.
3Adaptability or versatility
If mandrels with width equal to track distance are used, then off-track metal structures can be formed, but this requires precise spacing control
Solution Approach 1:
The SADP process is inherently self-aligned, where spacers automatically form at precise distances from mandrels based on conformal deposition thickness. This self-service mechanism eliminates the need for separate alignment steps and ensures consistent spacing precision without requiring additional manufacturing control measures.
Solution Approach 2:
The patent controls mandrel and spacer dimensions through material deposition parameters rather than lithographic patterning. By adjusting film thickness and deposition conditions, precise spacing is achieved through physical parameter control, which is more robust than dimensional control through patterning alone.
Data Source
AI summary
A method for efficient off-track routing and the resulting device are disclosed. Embodiments include: providing a hardmask on a substrate; providing a plurality of first mandrels on the hardmask; providing a first spacer on each side of each of the first mandrels; providing a plurality of first non-mandrel regions of the substrate being separated from the first mandrels and between two of the first spacers, each of the first mandrels, first non-mandrel regions, and first spacers having a width equal to a distance; and providing a second mandrel having a width of at least twice the distance and being separated from one of the first non-mandrel regions by a second spacer.