Oxide Thin-Film Bonding for Low-Temperature Electronic Packaging
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Solution Overview
Problem
Current bonding methods, such as atomic diffusion bonding and plasma-activated bonding, face challenges in achieving strong bonding without heating or at low temperatures, especially for heat-sensitive electronic devices, and require complex processes and expensive equipment, limiting their applicability and productivity.
Innovation Solution
A chemical bonding method using thin oxide films formed by vacuum deposition, where the bonding films are oxidized on their surfaces and hydrophilized by exposure to moisture, allowing bonding in air without the need for vacuum processing, enabling bonding of various materials with reduced costs and increased flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If atomic diffusion bonding or plasma-activated bonding is used to bond heat-sensitive electronic devices, then bonding strength can be achieved, but heating is required which damages heat-sensitive devices
Solution Approach 1:
The invention changes the bonding mechanism from thermal diffusion to chemical bonding via oxide thin films. By forming oxide films on bonding surfaces and utilizing chemical reactions between oxide films and base materials, bonding is achieved at room temperature or low temperatures without heating, thus protecting heat-sensitive electronic devices while maintaining strong bonding strength
Solution Approach 2:
The invention replaces the thermal field (heating) with a chemical field (oxide film reaction). Instead of using heat to activate diffusion bonding or plasma-activated bonding, the invention uses chemically active oxide thin films that react with base materials at room temperature, substituting a mechanical/thermal process with a chemical process
2Manufacturing precision
If vacuum deposition and vacuum processing are used for bonding, then bonding quality is improved, but process complexity and equipment cost increase
Solution Approach 1:
The invention extracts the oxide film formation step from the vacuum environment and performs it in air or oxygen-containing atmosphere. By forming oxide films on bonding surfaces before bonding (in air), the requirement for continuous vacuum processing is eliminated, simplifying the overall process while maintaining bonding quality through controlled oxide film formation
Solution Approach 2:
The invention performs preliminary oxidation of bonding surfaces by forming oxide thin films before the actual bonding process. This preliminary action of creating chemically active oxide films on surfaces allows subsequent bonding to proceed without requiring vacuum conditions during the bonding step itself, reducing process complexity
3Strength
If heating is applied for bonding, then bonding strength is improved, but alignment precision deteriorates due to thermal expansion differences
Solution Approach 1:
The invention changes the bonding temperature parameter from high temperature (heating) to room temperature or low temperature. By performing chemical bonding via oxide film reactions at low temperatures, thermal expansion differences between materials are minimized, maintaining alignment precision while achieving sufficient bonding strength through chemical rather than thermal mechanisms
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 method enables bonding of base materials in air, reducing costs and complexity, allowing for high-precision alignment and bonding of heat-sensitive devices without heating or at low temperatures, while maintaining strong bonding strength, and expanding the range of bondable materials.
Implementation Method 1
a step of forming a bonding film, which is a thin film of a metal or semiconductor formed by vacuum deposition and oxidized at least on its surface
Implementation Method 2
a step of exposing the surfaces of the bonding films formed on the two base materials to a space having moisture to hydrophilize the surfaces of the bonding films
Implementation Method 3
a step of forming a bonding film, which is a thin film of a metal or semiconductor formed by vacuum deposition
Data Source
AI summary
Substrates that are bonding targets are bonded in ambient atmosphere via bonding films, including oxides, formed on bonding faces of the substrates. The bonding films, which are metal or semiconductor thin films formed by vacuum film deposition and at least the surfaces of which are oxidized, are formed into the respective smooth faces of two substrates having the smooth faces that serve as the bonding faces. The bonding films are exposed to a space that contains moisture, and the two substrates are overlapped in the ambient atmosphere such that the surfaces of the bonding films are made to be hydrophilic and the surfaces of the bonding films contact one another. Through this, a chemical bond is generated at the bonded interface, and thereby the two substrates are bonded together in the ambient atmosphere. The bonding strength γ can be improved by heating the bonded substrates at a temperature.