Deep Source-Drain Backside Contacts With Liner Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional backside contact and placeholder fabrication techniques for nanosheet transistor structures require deep contact patterning, which increases the risk of shorting between source drain contacts and surrounding structures, posing challenges in fabricating reliable and efficient semiconductor devices.
Innovation Solution
The semiconductor structure incorporates deep source drain regions extending below the channel nanosheets into a backside dielectric layer, with liners separating these regions from the channel nanosheets and backside contact structures, allowing for electrical contact and reducing the risk of shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional backside contact fabrication techniques are used, then contact structures can be formed, but the risk of shorting between source drain contacts and surrounding structures increases
Solution Approach 1:
The source drain regions are extended vertically into the backside dielectric layer, creating a three-dimensional deep source drain structure. This vertical extension into a new dimension provides improved process margins and reduces the risk of shorting during backside contact patterning, as the contact can be formed at a different vertical level without compromising device integrity
Solution Approach 2:
A liner is introduced as an intermediary layer between the source drain regions and the backside dielectric layer. This liner acts as a protective barrier and etch stop during contact patterning processes, preventing direct contact between the source drain regions and surrounding structures, thereby eliminating the shorting risk while maintaining manufacturing feasibility
2Reliability
If deep contact patterning is performed to reach source drain regions, then electrical contact can be established, but the risk of shorting with surrounding structures increases
Solution Approach 1:
Instead of performing deep lateral contact patterning that risks shorting, the source drain regions are extended vertically into the backside dielectric layer. This dimensional change allows contact to be formed at a controlled depth without compromising device integrity, establishing reliable electrical contact while eliminating the shorting hazard
Solution Approach 2:
The liner serves as a protective intermediary between the source drain regions and the backside dielectric layer during contact patterning. It provides an etch stop and physical barrier that prevents the contact etch from damaging the source drain regions or creating shorts with surrounding structures, ensuring reliable contact formation
Data Source
AI summary
A nanosheet semiconductor structure including source drain regions arranged between channel nanosheets, where the source drain regions extend below a bottommost channel nanosheet into a backside dielectric layer, a liner surrounding at least a portion of the source drain regions, and backside contact structures in electrical contact with the source drain regions.