Damascene Interconnect Spacer for Ru-Co Interdiffusion Control
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Solution Overview
Problem
As interconnect technology scales to smaller sizes, the use of ruthenium as a wetting layer and cobalt as a cap in semiconductor components leads to catastrophic interdiffusion, forming voids and enabling electromigration due to their propensity for intermixing, which results in product failure.
Innovation Solution
A spacer is formed to separate the cap from the wetting layer, preventing direct contact and thus interdiffusion by recessing the interconnect structure and wetting layer relative to the dielectric layer, followed by depositing a spacer material that covers the exposed surfaces and is selectively etched to form spacers, ensuring the cap remains separated from the wetting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ruthenium wetting layer and cobalt cap are used in direct contact, then the interconnect structure can be formed with proper adhesion, but catastrophic interdiffusion occurs between the two materials forming voids and enabling electromigration
Solution Approach 1:
A spacer layer is introduced as an intermediary between the ruthenium wetting layer and the cobalt cap. This spacer prevents direct contact between the two materials that would otherwise undergo catastrophic interdiffusion, while still allowing the structure to function properly. The spacer acts as a physical barrier that maintains adhesion without enabling harmful material mixing.
Solution Approach 2:
The interface between the wetting layer and cap layer is segmented by introducing a spacer layer. Instead of having a direct interface between ruthenium and cobalt, the structure is divided into three distinct segments: wetting layer, spacer, and cap layer. This segmentation prevents the harmful interaction while maintaining the functional benefits of both materials.
2Reliability
If a spacer is formed to separate the cap from the wetting layer, then interdiffusion is prevented, but the device structure becomes more complex
Solution Approach 1:
The spacer serves as a thin intermediary layer that adds minimal structural complexity while providing maximum protective function. By using a thin film approach rather than bulky separation structures, the complexity increase is minimized while still achieving the goal of preventing interdiffusion.
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
Prevents catastrophic interdiffusion between ruthenium and cobalt, maintaining the integrity of the interconnect structure and reducing the risk of electromigration, thereby enhancing the reliability of semiconductor components.
Implementation Method 1
A spacer is formed to separate the cap from the wetting layer, preventing direct contact and thus interdiffusion
Implementation Method 2
recessing the interconnect structure and wetting layer relative to the dielectric layer, followed by depositing a spacer material that covers the exposed surfaces
Data Source
AI summary
A semiconductor component includes a dielectric layer including an opening. The semiconductor component further includes a liner arranged in the opening in direct contact with the dielectric layer. The semiconductor component further includes a wetting layer arranged in the opening in direct contact with the liner. The semiconductor component further includes an interconnect structure arranged in the opening in direct contact with the wetting layer. The semiconductor component further includes a cap arranged in the opening in direct contact with the interconnect structure and separated from the wetting layer by a spacer.