Backside Source/Drain Contacts for Lower-Resistance FET Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in fabricating integrated circuits with small dimensions and high packing density is the limited contact spacing and potential resistance issues due to the reliance on front-side contacts alone, which can be mitigated by incorporating backside contacts.
Innovation Solution
A method for fabricating semiconductor structures with backside contacts by forming sacrificial placeholders, exposing source/drain regions, and creating backside contacts that wrap around the sidewalls, providing increased contact area and electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only front-side contacts are used for FET connections, then the contact layout is simplified, but the contact spacing is limited and resistance increases
Solution Approach 1:
The patent introduces backside contacts that extend from the rear surface of the substrate to contact source/drain regions, adding a vertical dimension to the contact architecture. This allows electrical connections to be established through the substrate thickness rather than only across the surface, effectively increasing contact spacing and reducing resistance without complicating the front-side layout.
2Productivity
If contact spacing is reduced to increase packing density, then more FETs can be integrated, but resistance increases and manufacturing becomes more difficult
Solution Approach 1:
The contact system is segmented into front-side contacts and backside contacts that serve different functions. Front-side contacts handle signal routing while backside contacts provide power delivery and additional electrical connections. This segmentation allows each contact type to be optimized independently, enabling higher packing density without compromising manufacturing precision.
3Reliability
If backside contacts are added to increase contact area, then resistance decreases and power delivery improves, but device complexity increases
Solution Approach 1:
The backside contacts serve multiple functions simultaneously: they provide electrical connections to source/drain regions, establish power delivery networks, and increase effective contact area to reduce resistance. This multi-functionality achieves improved electrical connectivity without proportionally increasing device complexity, as a single structural element accomplishes multiple objectives.
Data Source
AI summary
Backside contacts wrapping around source/drain regions provide increased contact areas for electrical connections between field-effect transistors and metallization layers. Cavities formed within a device layer expose sidewalls of selected source/drain regions. The backside contacts extend within such cavities and adjoin the sidewall surfaces and bottom surfaces of the selected source/drain regions.