Nanosheet FET Structure for Short-Free Backside Contacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The formation of backside contacts in semiconductor devices with self-aligned substrate isolation layers can result in shorting to adjacent nanosheets or other structures due to the penetration of the isolation layer during placeholder structure creation.
Innovation Solution
The use of dummy nanosheet remnants vertically aligned with inner spacers, combined with a backside contact and a first source/drain structure, along with a first and second source/drain structure on sidewalls, and a gate stack, is employed to prevent shorting by creating additional space and using distinct interlayer dielectrics for etch selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If placeholder structures are formed by penetrating the self-aligned substrate isolation layer, then backside contacts can be formed, but shorting to adjacent nanosheets or other structures occurs
Solution Approach 1:
The substrate isolation layer is segmented into two distinct layers: a first substrate isolation layer and a second substrate isolation layer. This segmentation allows the first layer to be penetrated for placeholder structure formation while the second layer maintains isolation integrity, preventing shorting between adjacent structures.
Solution Approach 2:
The second substrate isolation layer is formed over the first substrate isolation layer before forming the placeholder structures. This preliminary action ensures that when the first isolation layer is penetrated, the second layer is already in place to prevent electrical shorting to adjacent nanosheets.
2Ease of manufacture
If the self-aligned substrate isolation layer is penetrated to form placeholder structures, then backside contacts can be created, but the isolation integrity is compromised
Solution Approach 1:
The substrate isolation function is segmented across two layers with different roles: the first layer facilitates placeholder structure formation through controlled penetration, while the second layer maintains continuous isolation integrity throughout the device structure.
Solution Approach 2:
The second substrate isolation layer acts as an intermediary protective layer that mediates between the penetration of the first isolation layer and the underlying nanosheet structures, preventing direct exposure and potential shorting.
Data Source
AI summary
Semiconductor devices include stacked nanosheet channels with inner spacers between respective pairs of the stacked nanosheet channels. Dummy nanosheet remnants are below respective inner spacers, vertically aligned with the respective inner spacers. A source/drain structure is on sidewalls of the plurality of stacked nanosheet channels. A backside contact makes contact with the source/drain structure.