Wafer Bonding Diffusion Preventing Layer AuSn Solder
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
AuSn eutectic bonding in wafer bonding processes faces issues with adhesive layer deterioration due to AuSn diffusion and damage to bonding parts during penetration wiring formation, especially when using etching or plating solutions.
Innovation Solution
A method involving a diffusion preventing layer with low wettability, such as platinum group metals, and a bonding layer that stays back of the edge of the diffusion preventing layer, preventing AuSn from spreading and diffusing into adhesive layers, and using conductive layers with high chemical resistance to protect against etching and plating solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer is provided between the wafer and bonding part to enhance adhesiveness, then bonding strength is improved, but AuSn diffusion into the adhesive layer deteriorates reliability
Solution Approach 1:
A diffusion preventing layer is introduced as an intermediary between the adhesive layer and the bonding part. This layer has low wettability with AuSn, preventing AuSn from diffusing into the adhesive layer while maintaining the adhesiveness provided by the adhesive layer.
Solution Approach 2:
The bonding structure uses a composite multi-layer configuration consisting of the adhesive layer, diffusion preventing layer, and bonding layer. Each layer serves a specific function: the adhesive layer provides bonding strength, the diffusion preventing layer blocks AuSn diffusion, and the bonding layer provides eutectic bonding capability.
2Device complexity
If the bonding part is formed of the same material as the penetration wiring to simplify structure, then manufacturing complexity is reduced, but the bonding part is damaged by etching or plating solutions
Solution Approach 1:
The bonding part is constructed as a composite structure with multiple layers including a bonding layer and a diffusion preventing layer. The diffusion preventing layer, made of material with high chemical resistance, protects the bonding part from damage by etching or plating solutions during penetration wiring formation.
Solution Approach 2:
Different layers of the bonding part have different material compositions tailored to specific functions. The diffusion preventing layer uses material with high chemical resistance specifically at the location where it contacts etching or plating solutions, while other layers maintain their original material properties for bonding and electrical functions.
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
Enhances the reliability of wafer bonding by preventing adhesive layer deterioration and protecting bonding parts from damage during penetration wiring formation, maintaining adhesiveness and structural integrity.
Implementation Method 1
a diffusion preventing layer formed of a material having low wettability with AuSn
Implementation Method 2
bonding the first bonding part and the second bonding part by eutectic bonding with an AuSn solder
Data Source
AI summary
A method for bonding wafers includes forming a first bonding part on a surface of a first wafer by stacking a diffusion preventing layer formed of a material having low wettability with AuSn above the first wafer and forming a bonding layer on a surface of the diffusion preventing layer such that the bonding layer stays back of an edge of the diffusion preventing layer, forming a second bonding part on a surface of a second wafer, and bonding the first bonding part and the second bonding part by eutectic bonding with an AuSn solder under a condition that the first wafer and the second wafer are opposed to each other.