Extended Side Contacts for Lower-Resistance Transistor Plugs
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Solution Overview
Problem
In the manufacturing of integrated circuits, existing contact plug formation processes struggle with achieving optimal adhesion and reducing contact resistance between source/drain contact plugs and gate electrodes, leading to inefficiencies in transistor performance.
Innovation Solution
The formation of both top and side contacts for the contact plugs, where the upper source/drain contact plug is intentionally vertically offset to etch and contact both the top and sidewall of the lower source/drain contact plug, enhancing adhesion and reducing contact resistance through improved electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional contact plug formation process is used, then the manufacturing process is simple, but the contact resistance is high and adhesion is poor
Solution Approach 1:
The contact plug structure transitions from a single top-contact configuration to a dual-contact configuration with both top and side contacts. The side contact extends laterally along the conductive feature, creating an additional contact interface that improves adhesion and reduces contact resistance without significantly complicating the overall formation process.
Solution Approach 2:
The top contact and side contact are merged into a single integrated contact plug structure. This unified structure provides both vertical and lateral contact interfaces with the conductive feature, simultaneously achieving improved adhesion and reduced contact resistance through the combined effect of both contact regions.
2Reliability
If contact plugs are formed only with top contact, then the formation process is straightforward, but contact resistance remains high
Solution Approach 1:
The contact plug extends from a single-point top contact into a multi-dimensional structure with lateral side contact. This dimensional expansion creates additional contact area with the conductive feature, improving electrical coupling effectiveness while maintaining compatibility with standard semiconductor fabrication processes.
Solution Approach 2:
The contact plug structure is optimized locally by extending the contact region along the side of the conductive feature. This local extension concentrates the contact interface where it is most needed, improving electrical coupling at the critical contact point without requiring global process changes.
3Stability of the object's composition
If conventional contact plugs are used, then the process is simple, but delamination issues occur
Solution Approach 1:
The contact plug structure adds a lateral dimension to the contact interface, extending along the side of the conductive feature. This dimensional change creates multiple adhesion points distributed along the contact length, distributing mechanical stress and preventing delamination that occurs with single-point top contacts.
Solution Approach 2:
The side contact is formed to establish adhesion before subsequent processing steps. By creating the lateral contact interface during the contact plug formation process, the structure is pre-configured with multiple adhesion points that prevent delamination in later manufacturing and device operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the adhesion between contact plugs and reduces contact resistance, thereby enhancing the performance and efficiency of transistors by ensuring better electrical connectivity.
Implementation Method 1
performing an etching process to etch the second inter-layer dielectric, the etch stop layer, and an upper portion of the first inter-layer dielectric to form an opening
Implementation Method 2
forming a lower source/drain contact plug over and electrically coupling to the source/drain region
Data Source
AI summary
A method includes forming a source/drain region for a transistor, forming a first inter-layer dielectric over the source/drain region, and forming a lower source/drain contact plug over and electrically coupling to the source/drain region. The lower source/drain contact plug extends into the first inter-layer dielectric. The method further includes depositing an etch stop layer over the first inter-layer dielectric and the lower source/drain contact plug, depositing a second inter-layer dielectric over the etch stop layer, and performing an etching process to etch the second inter-layer dielectric, the etch stop layer, and an upper portion of the first inter-layer dielectric to form an opening, with a top surface and a sidewall of the lower source/drain contact plug being exposed to the opening, and forming an upper source/drain contact plug in the opening.