Offset Contact Plugs for FinFET Bridge Prevention
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Solution Overview
Problem
As semiconductor devices become more highly integrated, forming contact plugs in a limited area becomes increasingly difficult, leading to issues such as bridge formation and increased leakage current due to the proximity of contact plugs and source/drain areas.
Innovation Solution
The semiconductor device incorporates contact plugs with offset centers and inclined interfaces, along with metal silicide layers, to prevent bridge formation and optimize electrical connections, while varying the dimensions and materials of source/drain areas and contact plugs to enhance integration and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If contact plugs are formed in a limited area to achieve high integration, then integration density is improved, but bridge formation and leakage current increase
Solution Approach 1:
The contact plugs are formed with asymmetric positioning relative to the source/drain areas. Specifically, the contact plugs are offset from the centers of the source/drain areas, creating non-uniform spacing that prevents bridge formation while maintaining high integration density. This asymmetric configuration allows closer spacing without the risk of adjacent contact plugs merging.
2Area of stationary object
If contact plugs are positioned closer together to increase integration, then device density is improved, but the risk of bridge formation increases
Solution Approach 1:
The offset configuration creates locally optimized spacing between contact plugs and source/drain areas. By positioning contact plugs asymmetrically, the design achieves different spacing characteristics in different regions, allowing closer overall spacing while maintaining sufficient clearance at critical interfaces to prevent bridges.
3Ease of manufacture
If conventional aligned contact plugs are used, then manufacturing is simple, but leakage current increases due to proximity effects
Solution Approach 1:
The contact plugs are deliberately misaligned with the source/drain areas by offsetting their centers. This asymmetric positioning reduces the overlapping electric field regions between adjacent contact plugs and source/drain structures, thereby minimizing leakage current paths while remaining compatible with standard manufacturing processes.
Data Source
AI summary
A semiconductor device including a first fin active area substantially parallel to a second fin active area, a first source/drain in the first fin active area, a second source/drain in the second fin active area, a first contact plug on the first source/drain, and a second contact plug on the second source/drain. The center of the second contact plug is offset from the center of the second source/drain.