Dummy Shoulder Structure for Semiconductor Line Stress Reduction
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Solution Overview
Problem
The challenge in semiconductor integrated circuitry is the variability in metal linewidth due to the optical proximity effect and surface topography, leading to stress defects like metal pits and line breaks at the dense-to-isolated line transitional areas, despite the use of Optical Proximity Correction models and sophisticated design rules.
Innovation Solution
The introduction of dummy line shoulders, which are conductive features formed perpendicular to isolated lines and not connected to the interconnecting circuitry, serve as a protective structure to mitigate line stress at the transitional areas, improving linewidth uniformity without affecting the process window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Optical Proximity Correction (OPC) models and sophisticated design rules are implemented, then linewidth control is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by adding dummy line shoulders to the layout design before manufacturing. These dummy features are pre-positioned at dense-to-isolated line transitions to proactively compensate for anticipated stress effects during processing, eliminating the need for complex OPC models and sophisticated design rules while achieving the same linewidth control objective
Solution Approach 2:
The patent applies local quality by introducing dummy line shoulders specifically at dense-to-isolated line transition regions where stress effects occur, rather than applying uniform corrections across the entire wafer. This localized approach reduces processing complexity by targeting only the problematic areas with simple geometric additions
2Manufacturing precision
If dummy line shoulders are added to reduce line stress, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies this principle by using simple dummy line shoulder features that are easy to add to the layout and process. These dummy features serve their purpose of reducing line stress during manufacturing and can be easily removed or ignored in subsequent design iterations, representing a low-cost, temporary solution to a complex problem
Solution Approach 2:
The patent applies segmentation by dividing the line structure into distinct regions: dense lines, isolated lines, and transitional regions with dummy shoulders. This segmentation allows the dummy features to be independently added only where needed at transitions, rather than modifying the entire layout, thus minimizing the increase in layout complexity
Data Source
AI summary
Semiconductor integrated circuit line structures for improving a process window in the vicinity of dense-to-isolated pattern transition areas and a technique to implement the line structures in the layout process are described in this disclosure. The disclosed structure includes a semiconductor substrate, and a material layer above the substrate. The material layer has a closely spaced dense line structure, an isolated line structure next to the dense line structure, and a dummy line shoulder structure formed in the vicinity of the dense line and the isolated line structures. One end of the dummy line shoulder structure connects to the isolated line structure and another end extends away from the isolated line structure in an orientation substantially perpendicular to the isolated line structure.