Double Patterning Routing Without Stitching
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Solution Overview
Problem
Current double patterning routing methods in semiconductor fabrication often require stitching, which is not supported by all manufacturing facilities, leading to unimplementable masks due to the inability to assign connection routes entirely to a single mask.
Innovation Solution
An enhanced routing module that tracks mask selection constraints during maze expansion to create 'correct-by-construction' connection routes, ensuring each route can be assigned to a single mask, thereby avoiding the stitching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If double patterning routing methods are used to achieve minimum pitch features, then manufacturing precision is improved, but device complexity increases due to the need for stitching
Solution Approach 1:
The routing algorithm performs preliminary actions by tracking mask constraints during the routing process itself, ensuring that routes are assigned to a single mask before fabrication begins. This prevents the need for stitching operations during manufacturing.
Solution Approach 2:
The patent introduces constraint tracking as an intermediary mechanism between the routing algorithm and mask assignment. This intermediary tracks which mask each segment of the route can be assigned to, ensuring single-mask compatibility without requiring stitching.
2Productivity
If connection routes are assigned to multiple masks to achieve routing density, then productivity is improved, but manufacturing precision deteriorates due to stitching requirements
Solution Approach 1:
The algorithm performs preliminary mask compatibility checking during the routing process, ensuring that high-density routes can be assigned to a single mask before fabrication. This maintains both routing density and connection continuity without stitching.
Solution Approach 2:
The constraint tracking mechanism provides feedback during routing about which masks are compatible with each route segment. This feedback allows the algorithm to maintain high routing density while ensuring single-mask assignability.
3Ease of operation
If stitching is used to complete connections across masks, then ease of operation is improved for double patterning, but reliability deteriorates in facilities that do not support stitching
Solution Approach 1:
The constraint tracking system acts as an intermediary that ensures routing solutions are compatible with facilities that do not support stitching. It mediates between double patterning requirements and fabrication capabilities by guaranteeing single-mask route assignability.
Solution Approach 2:
The routing algorithm serves itself by internally tracking mask constraints and automatically ensuring single-mask compatibility. This self-service approach eliminates dependence on external stitching capabilities, improving fabrication compatibility.
Data Source
AI summary
An approach is provided in which an enhanced routing module creates connection objects on a double patterning layout that are correct-by-construction and do not require a semiconductor fabrication stitching process. The enhanced routing module efficiently tracks accumulated mask selection constraints, during maze expansion, when the enhanced routing module traverses possible connection routes from a source grid point to a target grid point. In turn, the enhanced routing module avoids grid points that impose mask selection constraints that are incompatible with existing mask selection constraints of the possible connection routes. As a result, a connection object created by any one of the possible connection routes can be assigned to a specific mask, thus avoiding stitching process requirements from a semiconductor fabrication facility.