Copper-Oxide Hybrid Bonding for Delamination-Resistant Assembly
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Solution Overview
Problem
The manufacturing of electronic devices, particularly optoelectronic devices with copper and oxide layers, faces issues of lack of adherence and delamination at interfaces, which worsens during thermal treatments, affecting the quality and integration of metallic optical filters with optical sensors.
Innovation Solution
A method involving hybrid bonding of copper regions with oxide or oxidized metal regions, using structured layers formed by damascene methods, where copper portions are in contact with oxide or oxidized metal, and including anneal steps to enhance adherence without the need for intermediate dielectric layers that alter optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dielectric layer made of oxide is stacked on a copper layer, then metallic optical filters can be formed, but lack of adherence and delamination occur at the interface during thermal treatment
Solution Approach 1:
A thin adhesion layer made of titanium (Ti) or titanium nitride (TiN) is introduced between the copper layer and the oxide dielectric layer. This intermediary layer acts as a mediator that chemically bonds to both copper and oxide, preventing delamination during thermal treatment while maintaining the electrical and optical properties of the structure.
Solution Approach 2:
The interface structure is designed as a composite multilayer system comprising copper, adhesion layer (Ti/TiN), and oxide dielectric. This composite structure combines the electrical conductivity of copper, the adhesion properties of titanium-based materials, and the insulating properties of oxide, achieving both electrical functionality and mechanical stability.
2Reliability
If intermediate dielectric layers are added to prevent delamination, then adherence improves, but optical properties are altered
Solution Approach 1:
The adhesion layer is applied locally only at the copper-oxide interface where adhesion is needed, rather than as a thick intermediate dielectric layer throughout the structure. This localized application maintains the overall optical properties of the filter while providing adhesion only where required.
Solution Approach 2:
The thickness of the adhesion layer is precisely controlled at nanometer scale (typically 1-5 nm), which is sufficient to provide chemical adhesion between copper and oxide but thin enough to be optically transparent or negligible, thus preserving the optical interference properties of the filter.
3Productivity
If copper layers are used in optical filters, then manufacturing efficiency improves, but delamination occurs during thermal treatment
Solution Approach 1:
The adhesion layer is deposited on the copper surface before the oxide dielectric layer is formed, creating a pre-prepared interface that is resistant to thermal delamination. This preliminary action of surface preparation ensures that subsequent thermal processing steps do not cause delamination, maintaining manufacturing efficiency.
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 prevents delamination and maintains optical performance by ensuring stable contact between copper and oxide layers, allowing for effective integration of filters with optical sensors without compromising the filter's design or manufacturing complexity.
Implementation Method 1
the first and second surfaces are assembled by means of a hybrid bonding such that the entire first copper region is placed into contact with the oxide or the oxidized metal of the second region
Implementation Method 2
including anneal steps to enhance adherence
Data Source
AI summary
The present description concerns a method of assembly of a first assembly layer comprising a first copper region at a first surface and of a second assembly layer comprising a second region made of oxide or of an oxidized metal at a second surface, wherein the first and second surfaces are assembled by means of a hybrid bonding such that the entire first copper region is placed into contact with the oxide or the oxidized metal of the second region.