Shared Source/Drain Contact Layout for Stacked FET Scaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nanosheet technology faces challenges in scaling down due to device interference and difficulty in forming connections to a backside power network as devices become smaller and closer together.
Innovation Solution
A semiconductor device structure with a shared source/drain contact extending through both upper and lower source/drain regions, connected by an isolation interlayer dielectric (ILD) for optimized contact formation, and independent source/drain contacts formed from both frontside and backside, with additional BEOL and backside interconnects for enhanced connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If devices are scaled down and placed closer together, then device density and integration are improved, but device interference increases and connection formation becomes more difficult
Solution Approach 1:
The patent introduces a vertical dimension by forming shared source/drain contacts that extend through multiple stacked nanosheet layers. This three-dimensional contact structure allows connections to penetrate through the stacked device architecture, enabling backside power network connections while maintaining high device density in the horizontal plane without causing interference.
Solution Approach 2:
The contact structure is segmented into multiple independent contacts: shared source/drain contacts that extend vertically through stacked nanosheets, and independent source/drain contacts at the frontside and backside. This segmentation allows each contact type to serve specific functions, resolving the interference issue by providing dedicated connection paths.
2Productivity
If devices are scaled down and placed closer together, then device density is improved, but forming connections to backside power network becomes more difficult
Solution Approach 1:
The shared source/drain contacts extend in the vertical dimension through the stacked nanosheet structure, enabling direct connections to the backside power network. This vertical penetration simplifies backside connection formation compared to trying to route connections laterally through densely packed scaled-down devices.
Solution Approach 2:
The shared source/drain contacts serve multiple functions: they provide electrical connections for both frontside and backside access, serve as power network connections, and maintain device density. This multi-functionality simplifies the overall connection formation process by consolidating multiple requirements into a single contact structure.
3Reliability
If shared source/drain contact is formed extending through upper and lower source/drain, then contact resistance is reduced, but isolation complexity increases
Solution Approach 1:
The isolation structure is segmented into distinct regions: shared source/drain contacts are isolated from independent source/drain contacts using isolation ILD. This segmentation allows each contact type to be optimized independently while maintaining overall system reliability and reducing interference between different contact functions.
Data Source
AI summary
According to the embodiment of the present invention, a semiconductor device comprises a first nanodevice including a plurality of first upper transistors and a plurality of first lower transistors. The first nanodevice includes a first upper source/drain and a first lower source/drain. A shared source/drain contact extends through the first upper source/drain and the first lower source/drain. An isolation interlayer dielectric (ILD) is in direct contact with at least one surface of the shared source/drain contact.