Metal-to-Source/Drain Plug Gap Patterning for Tighter Contact Spacing
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Solution Overview
Problem
The island patterning technique for semiconductor devices like finFETs results in metal contacts being separated by a minimum distance of 19 nanometers, leading to increased resistance due to a less interface between source/drain and metal-to-source/drain plugs, which is not suitable for designs requiring closer separation and better interface.
Innovation Solution
The gap patterning method involves forming a mask layer on dielectric layers over source/drain plugs, creating openings, filling with metal, and forming gaps to create metal contacts separated by less than 19 nanometers, with the gap filled by dielectric material to reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the island patterning technique is used to form metal contacts, then the metal contacts are separated by a minimum distance of 19 nanometers, but this results in increased resistance due to a less interface between source/drain and metal-to-source/drain plugs
Solution Approach 1:
The patent applies segmentation by dividing the metal contact formation process into two distinct stages: first forming a continuous metal layer that provides good interface contact with source/drain, then creating gaps in this layer to separate the metal contacts. This segmentation allows the metal contacts to be separated by less than 19 nanometers while maintaining a substantial interface between the source/drain and the metal-to-source/drain plugs, thereby resolving the contradiction between achieving closer contact spacing and maintaining interface quality.
2Reliability
If metal contacts are separated by less than 19 nanometers, then the interface between source/drain and metal-to-source/drain plugs is improved, but this requires a different patterning method than conventional island patterning
Solution Approach 1:
The patent applies preliminary action by first forming the complete metal layer that provides optimal interface contact with the source/drain structures before any gap formation occurs. This preliminary metal layer formation ensures the interface quality is established early in the process. Subsequently, gaps are created in this pre-formed metal layer to achieve the desired contact separation. This sequence of operations simplifies the overall manufacturing process compared to attempting to directly pattern separated metal contacts, as the gap formation can be achieved through standard lithography and etching processes applied to the already-formed metal layer.
Data Source
AI summary
A method may include forming a mask layer on top of a first dielectric layer formed on a first source/drain and a second source/drain, and creating an opening in the mask layer and the first dielectric layer that exposes portions of the first source/drain and the second source/drain. The method may include filling the opening with a metal layer that covers the exposed portions of the first source/drain and the second source/drain, and forming a gap in the metal layer to create a first metal contact and a second metal contact. The first metal contact may electrically couple to the first source/drain and the second metal contact may electrically couple to the second source/drain. The gap may separate the first metal contact from the second metal contact by less than nineteen nanometers.