Hybrid Bond Contact Buffer Layer for Cu-Al Interface Resistance
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Solution Overview
Problem
Current semiconductor packaging methods, such as chip on film (COF), chip on glass (COG), and chip on plastic (COP), are inadequate for the increasingly refined dimensions of semiconductor devices, necessitating higher precision and smaller dimensions to meet technological demands, and hybrid bonding methods face challenges with high interface resistance between copper and aluminum components.
Innovation Solution
A semiconductor structure with a hybrid bond contact featuring a composite buffer layer comprising titanium, titanium nitride, tantalum nitride, and tantalum layers between copper and aluminum components, along with an aluminum-titanium intermetallic layer formed during heating, to reduce interface resistance and prevent atomic diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a direct interface between copper and aluminum components is used in hybrid bonding, then the manufacturing process is simpler, but the interface resistance between copper and aluminum becomes excessively high
Solution Approach 1:
The interface between copper and aluminum is segmented into multiple sequential layers (titanium layer, titanium nitride layer, tantalum nitride layer, tantalum layer) instead of a direct contact. This segmentation allows each layer to perform specific functions: titanium and titanium nitride provide strong adhesion to copper, while tantalum nitride and tantalum provide low-resistance contact with aluminum, collectively reducing interface resistance while maintaining manufacturing feasibility
Solution Approach 2:
The composite buffer layer acts as an intermediary between copper and aluminum components. The titanium and titanium nitride layers serve as intermediaries that facilitate bonding between copper and the buffer structure, while the tantalum nitride and tantalum layers serve as intermediaries that reduce resistance between the buffer and aluminum, effectively mediating the interface properties
2Device complexity
If copper and aluminum components are directly bonded without a buffer layer, then the device complexity is reduced, but aluminum atoms diffuse into other components during heating processes
Solution Approach 1:
The composite buffer layer, particularly the titanium and titanium nitride layers, serves as a diffusion barrier that mediates between aluminum and other components. During heating processes, these layers prevent aluminum atoms from diffusing into copper or other sensitive materials, maintaining compositional stability while the layer thickness is optimized to balance diffusion protection with device complexity
Solution Approach 2:
The buffer layer is constructed as a composite material system combining different metals and metal nitrides, each selected for specific properties: titanium and titanium nitride provide diffusion barrier capabilities and adhesion, while tantalum nitride and tantalum provide low resistance and thermal stability. This composite structure effectively blocks aluminum diffusion while managing the complexity through functional integration
3Reliability
If a composite buffer layer with multiple layers is added between copper and aluminum, then the interface resistance is reduced and aluminum diffusion is prevented, but the device complexity increases
Solution Approach 1:
The buffer layer is segmented into four distinct functional layers, each with optimized thickness and material composition. This segmentation allows precise control over interface resistance and diffusion barriers while enabling systematic manufacturing processes where each layer can be deposited and controlled independently, managing complexity through modular construction
Solution Approach 2:
Each layer within the composite buffer layer possesses locally optimized properties: the titanium layer provides strong copper adhesion, the titanium nitride layer provides diffusion barrier and adhesion, the tantalum nitride layer provides low resistance and diffusion barrier, and the tantalum layer provides low resistance contact with aluminum. This local quality optimization achieves high reliability while the overall structure remains manageable through clear functional differentiation
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
The buffer layer structure effectively reduces interface resistance and prevents aluminum diffusion, enhancing the quality and yield of semiconductor components by improving conductivity and maintaining structural integrity during manufacturing processes.
Implementation Method 1
during the heating process, an aluminum-titanium layer is formed between the aluminum component and the titanium layer to prevent the diffusion of aluminum atoms into other components
Data Source
AI summary
The present invention provides a semiconductor structure containing a hybrid bond contact, comprising a first hybrid bond contact located in a dielectric layer. The first hybrid bond contact is consisting of copper. A first top wiring layer is situated within the dielectric layer and below the first hybrid bond contact, wherein the first top wiring layer is made of aluminum. A first composite liner layer is positioned between the first hybrid bond contact and the first top wiring layer. From a cross-sectional view, the first composite liner layer encapsulates the sidewalls and bottom surface of the first hybrid bond contact. The first composite liner layer consists of a titanium layer, a titanium nitride layer, a tantalum nitride layer, and a tantalum layer.