Metal Cut Layout Shifting for Sub-Minimum Pattern Spacing
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Solution Overview
Problem
In semiconductor integrated circuit (IC) fabrication, the resolution of photoresist patterns blurs at around 45 nanometer half pitch, leading to native conflicts due to minimum separation distance violations, which existing multi-exposure methods struggle to resolve effectively.
Innovation Solution
The implementation of a metal cut process that involves joining patterns closer than the minimum separation distance using multiple masks and shifting a single cut mask to reuse it for multiple exposures, allowing for the reduction of mask costs and enhanced flexibility in patterning by forming complete-paired patterns and using dummy cuts to achieve smaller spacings without violating minimum separation distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-exposure methods are used to continue using fabrication equipment for larger technology nodes, then productivity is improved by extending equipment life, but manufacturing precision deteriorates due to resolution blurring at 45nm half pitch
Solution Approach 1:
The patent segments the patterning process into multiple discrete exposure steps, each handling a subset of patterns. By dividing the overall pattern formation into separate mask exposures, the system can maintain larger feature sizes in each individual exposure while achieving the overall dense pattern layout, thus preserving manufacturing precision while extending equipment utilization.
Solution Approach 2:
The patent introduces the temporal dimension by using sequential multi-exposure processing. Instead of attempting to form all patterns in a single exposure, the system uses multiple exposures at different time points, allowing each exposure to focus on specific pattern regions with adequate spacing, thereby maintaining resolution while achieving high-density overall patterns.
2Manufacturing precision
If patterns are formed closer than minimum separation distance using multiple masks, then manufacturing precision is improved by achieving smaller spacings, but device complexity increases due to multiple mask assignments and conflict resolution
Solution Approach 1:
The patent performs preliminary conflict detection and resolution in the design stage by identifying patterns that would violate minimum separation distances. Dummy patterns are pre-inserted at strategic locations to prevent native conflicts before fabrication, simplifying the actual multi-mask patterning process and reducing runtime complexity while achieving sub-minimum-spacing patterns.
Solution Approach 2:
The patent introduces dummy patterns as intermediary elements that mediate between conflicting pattern requirements. These dummy patterns act as buffers or placeholders that resolve spacing conflicts without requiring complex real-time adjustments during the patterning process, thereby reducing device complexity while enabling smaller effective spacings.
3Manufacturing precision
If every possible combination of mask assignments is checked for minimum spacing compliance, then manufacturing precision is maintained by avoiding native conflicts, but productivity deteriorates due to computational overhead
Solution Approach 1:
The patent performs comprehensive spacing compliance checks and conflict resolution during the layout design stage rather than during manufacturing. By pre-processing the layout to identify and resolve all potential native conflicts, the system ensures manufacturing precision is maintained while avoiding computational overhead during the actual fabrication process, thus improving productivity.
Data Source
AI summary
A method includes: providing a first layout of a first layer over a substrate, the first layer having at least one metal pattern, and generating a second layout by placing a cut mask at a first position relative to the substrate to remove material from a first region of the at least one metal pattern to provide a first metal pattern and placing the cut mask at a second position relative to the first layer over the substrate to remove material from a second region of the at least one metal pattern to provide a second metal pattern.