Hybrid Bonding Interface for 3D Chip Integration
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Solution Overview
Problem
The bonding of substrates in three-dimensional integration faces challenges with adhesion strength and containment of interfacial impurity diffusion, particularly due to rapid diffusion of conductive materials like copper in TSV structures, leading to electrical shorts and reliability issues.
Innovation Solution
A bonded structure is created using substrates with recessed regions filled with bondable dielectric materials like silicon oxide, surrounded by diffusion-resistant materials like silicon nitride, which provides high adhesion strength and encapsulates TSV structures to prevent metal diffusion, ensuring reliable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diffusion resistant materials are used to prevent metal diffusion, then reliability is improved, but adhesion strength deteriorates
Solution Approach 1:
The bonding interface is segmented into multiple functional regions: diffusion resistant material regions for preventing metal diffusion and bondable dielectric material regions for providing adhesion strength. This segmentation allows each region to specialize in one function, resolving the contradiction between reliability and adhesion strength.
Solution Approach 2:
Different material properties are applied locally at the bonding interface. Diffusion resistant materials (such as silicon nitride) are placed in regions where metal diffusion prevention is critical, while bondable dielectric materials (such as silicon oxide) are placed in regions where adhesion is critical. This local differentiation allows simultaneous optimization of both reliability and adhesion strength.
2Strength
If metal pad area is increased to provide sufficient adhesion strength, then adhesion strength is improved, but the area for TSV structures is reduced
Solution Approach 1:
The substrate surface is segmented into distinct functional zones: metal pad regions for adhesion, TSV regions for electrical connection capacity, and diffusion resistant material regions for reliability. This segmentation allows optimization of each function independently without compromising others.
Solution Approach 2:
The bonding interface structure is designed to perform multiple functions simultaneously through different material regions: adhesion provision, metal diffusion prevention, and electrical signal/power transmission support. This multi-functionality resolves the contradiction between adhesion strength and TSV capacity.
3Strength
If bondable dielectric material is used to provide adhesion, then adhesion strength is improved, but containment of interfacial impurity diffusion deteriorates
Solution Approach 1:
The dielectric material at the bonding interface is segmented into bondable dielectric material portions for adhesion and diffusion resistant dielectric material portions for containing impurity diffusion. This segmentation allows each material type to perform its specialized function without compromise.
Solution Approach 2:
The bonding interface employs a composite structure combining bondable dielectric materials and diffusion resistant dielectric materials in specific spatial arrangements. This composite approach allows simultaneous achievement of adhesion strength and diffusion containment that neither material could achieve alone.
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 enhances adhesion strength between substrates while containing interfacial impurity diffusion, preventing electrical shorts and improving the reliability of three-dimensional integrated structures.
Implementation Method 1
adhesion between two dielectric materials as in an oxide-to-oxide bonding that fuses silicon dioxide materials from two substrates after bonding
Implementation Method 2
the diffusion resistant materials retard lateral diffusion of the conductive material from the TSV structures along the interface between two bonded substrates, thereby preventing electrical shorts
Data Source
AI summary
Each of a first substrate and a second substrate includes a surface having a diffusion resistant dielectric material such as silicon nitride. Recessed regions are formed in the diffusion resistant dielectric material and filled with a bondable dielectric material. The patterns of the metal pads and bondable dielectric material portions in the first and second substrates can have a mirror symmetry. The first and second substrates are brought into physical contact and bonded employing contacts between metal pads and contacts between the bondable dielectric material portions. Through-substrate-via (TSV) structures are formed through bonded dielectric material portions. The interface between each pair of bonded dielectric material portions located around a TSV structure is encapsulated by two diffusion resistant dielectric material layers so that diffusion of metal at a bonding interface is contained within each pair of bonded dielectric material portions.