FinFET Contact Structure With Non-Uniform Bottom Surface
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Solution Overview
Problem
As integrated circuit devices are downscaled, they experience a short channel effect that deteriorates their reliability, necessitating the integration of fin-type active areas to mitigate this issue.
Innovation Solution
The integration of a contact structure with a non-uniform bottom surface and silicide layers alternately arranged with residual barriers, which increases the contact area between source/drain structures and the contact structure, providing a more reliable electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If integrated circuit devices are downscaled to increase integration, then productivity and integration density are improved, but short channel effect occurs causing deterioration in reliability
Solution Approach 1:
The patent introduces fin-type active areas that extend vertically from the substrate, transitioning from a planar 2D structure to a 3D vertical structure. This dimensional change increases the effective channel area for current flow while maintaining a small footprint, thereby improving integration density without suffering from short channel effects that plague scaled-down planar transistors.
Solution Approach 2:
The source/drain regions are divided into multiple merged source/drain structures within each source/drain area. This segmentation increases the total contact area with the contact structure, reducing contact resistance and improving electrical connection reliability while maintaining compact device dimensions.
2Productivity
If contact structure size is reduced to meet reduced design rules, then integration density is improved, but electrical connection reliability deteriorates
Solution Approach 1:
The contact structure is given a non-uniform bottom surface that extends vertically to contact different levels of the merged source/drain structures. This vertical dimensionality allows the contact structure to maintain a small planar footprint while achieving extensive contact area with the source/drain regions, thereby reducing contact resistance without violating design rules.
Solution Approach 2:
The bottom surface of the contact structure is designed with non-uniform height, creating different contact depths at different locations. This local variation in contact depth allows optimal contact with each merged source/drain structure, ensuring reliable electrical connection while maintaining overall compact dimensions.
3Reliability
If fin-type active areas are introduced to reduce short channel effect, then device reliability is improved, but device complexity increases
Solution Approach 1:
The source/drain areas are segmented into multiple merged source/drain structures that align with the fin-type active areas. This segmentation approach maintains the beneficial vertical fin structure for reducing short channel effects while organizing the contact interface in a systematic, manufacturable pattern that does not excessively increase processing complexity.
Data Source
AI summary
An integrated circuit device includes a fin-type active area that extends on a substrate in a first direction, a gate structure that extends on the substrate in a second direction and crosses the fin-type active area, source/drain areas arranged on first and second sides of the gate structure, and a contact structure electrically connected to the source/drain areas. The source/drain areas comprise a plurality of merged source/drain structures. Each source/drain area comprises a plurality of first points respectively located on an upper surface of the source/drain area at a center of each source/drain structure, and each source/drain area comprises at least one second point respectively located on the upper surface of the source/drain area where side surfaces of adjacent source/drain structures merge with one another. A bottom surface of the contact structure is non-uniform and corresponds to the first and second points.