Air-Gap Source/Drain Contact Support Against Tilting During Scaling
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Solution Overview
Problem
As the minimum feature sizes in semiconductor devices are reduced, challenges arise in maintaining the integration density and preventing issues such as tilting of contacts due to lack of structural support during processing.
Innovation Solution
The implementation of a base layer and sacrificial spacers with a scaffold provides additional structural support to the first contact, ensuring stability and preventing tilting during the formation of air-gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If minimum feature sizes are reduced to improve integration density, then more components can be integrated into a given area, but structural support during processing becomes insufficient leading to contact tilting
Solution Approach 1:
The patent introduces a sacrificial spacer structure that is formed before the contact structure. This sacrificial spacer provides preliminary structural support during the fabrication process, preventing contact tilting. After serving its support function, the sacrificial spacer is removed, having fulfilled its temporary structural role without interfering with the final device performance.
Solution Approach 2:
The sacrificial spacer acts as an intermediary structure between the contact structure and the underlying substrate. It provides the necessary structural support during processing, then is removed to leave the final contact structure. This intermediary element enables the fabrication of high-density devices while maintaining structural integrity during manufacturing.
2Reliability
If sacrificial spacers are removed to form air-gaps for electrical isolation, then capacitance between adjacent contacts is reduced, but structural support is lost leading to contact tilting
Solution Approach 1:
The patent forms the contact structure with the sacrificial spacer in place before removing the spacer. This preliminary formation ensures that the contact structure is established with proper structural support and alignment. Only after the contact structure is securely formed is the sacrificial spacer removed to create the air-gap for electrical isolation.
Solution Approach 2:
The sacrificial spacer provides beforehand cushioning or support to the contact structure during the critical formation phase. This temporary support prevents tilting and ensures proper structural composition. Once the contact structure is firmly established, the sacrificial spacer is removed, having provided the necessary preliminary protection and support.
3Reliability
If air-gaps are formed between contacts for electrical isolation, then parasitic capacitance is reduced, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The patent combines the formation of the sacrificial spacer with the existing contact formation process flow. The sacrificial spacer is integrated into the fabrication sequence as a temporary structural element that is formed, serves its support function, and is then removed. This merging approach adds minimal complexity while achieving the electrical isolation benefit.
Solution Approach 2:
The sacrificial spacer serves as a temporary intermediary that enables the air-gap formation without significantly complicating the manufacturing process. It is formed using standard deposition techniques, provides structural support during contact formation, and is removed to create the electrical isolation. This intermediary approach achieves reliable electrical isolation with manageable manufacturing complexity.
Data Source
AI summary
A semiconductor device and method of manufacture are provided which help to support contacts while material is removed to form air gaps. In embodiments a contact is formed with an enlarged base to help support overlying portions of the contact. In other embodiments a scaffold material may also be placed prior to the formation of the air gaps in order to provide additional support.