Source/Drain Contact Spacers for Integrated Circuit Parasitic Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional source/drain contact structures in integrated circuits encroach into source/drain features, causing increased parasitic resistance and delaying signal routing, which hampers performance and efficiency in advanced IC technology nodes.
Innovation Solution
The method involves forming source/drain contact spacers that do not physically contact or encroach into source/drain features, by etching an interlayer dielectric layer to expose a contact etch stop layer, depositing a spacer layer, and extending the contact opening to create spacers that define the sidewalls, thereby reducing parasitic resistance and improving current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional source/drain contact structures are used, then contact connections are established, but parasitic resistance increases and current flow is impeded
Solution Approach 1:
The patent extracts and removes the harmful encroachment of contact structures into source/drain features. By using spacer-based formation methods, the contact structures are prevented from invading the source/drain region, thereby eliminating the source of parasitic resistance while maintaining necessary electrical connections.
Solution Approach 2:
The patent introduces spacer structures as intermediary elements between the contact openings and source/drain features. These spacers act as mediators that define precise boundaries and prevent direct encroachment, thereby reducing parasitic resistance at the interface while still allowing functional contact connections.
2Ease of operation
If contact structures encroach into source/drain features, then contact connections are formed, but signal routing is delayed
Solution Approach 1:
The patent extracts the problematic encroachment behavior from contact structure formation. By using spacer-defined boundaries, contact structures are prevented from invading source/drain features, thereby eliminating the cause of signal routing delays while maintaining proper electrical connectivity.
Solution Approach 2:
The patent applies preliminary action by forming spacer structures before final contact formation. These spacers pre-establish the boundaries and prevent encroachment in advance, ensuring that signal routing paths remain clear and unobstructed from the outset of the fabrication process.
3Ease of manufacture
If conventional contact formation methods are used, then manufacturing is simplified, but manufacturing precision deteriorates
Solution Approach 1:
The patent employs self-service principles where spacer structures automatically define the boundaries of contact regions. The spacers form conformally and self-align to the underlying features, eliminating the need for separate alignment steps and achieving high precision through the self-organizing nature of the spacer formation process.
Solution Approach 2:
The spacer structures serve as intermediary elements that mediate between the contact openings and source/drain features. They provide precise boundary definition and alignment control, enabling manufacturing precision to be maintained or improved while using relatively simple conformal deposition processes.
Data Source
AI summary
Source/drain contact spacers for improving integrated circuit device performance and methods of forming such are disclosed herein. An exemplary method includes etching an interlayer dielectric (ILD) layer to form a source/drain contact opening that exposes a contact etch stop layer (CESL) disposed over a source/drain feature, depositing a source/drain contact spacer layer that partially fills the source/drain contact opening and covers the ILD layer and the exposed CESL, and etching the source/drain contact spacer layer and the CESL to extend the source/drain contact opening to expose the source/drain feature. The etching forms source/drain contact spacers. The method further includes forming a source/drain contact to the exposed source/drain feature in the extended source/drain contact opening. The source/drain contact is formed over the source/drain contact spacers and fills the extended source/drain contact opening. A silicide feature can be formed over the exposed source/drain feature before forming the source/drain contact.