Laser Bonding Intermediate Layer for Hermetic Sealing
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Solution Overview
Problem
Direct bonding techniques in the semiconductor and electronics industry often cause thermal damage and warping due to elevated temperatures and mismatched thermal expansion coefficients, leading to weakened bonds and reduced hermeticity in component packages.
Innovation Solution
A laser bonding process that uses an intermediate layer between substrates, where electromagnetic radiation is applied to heat the layer and form a strong, transparent, and corrosion-resistant bond at room temperature, avoiding the need for high-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct bonding techniques are used to bond substrates together, then the substrates can be bonded without adhesive agents, but thermal damage and warping occur due to elevated temperatures and mismatched thermal expansion coefficients
Solution Approach 1:
A bonding agent layer is introduced as an intermediary between the first and second substrates. This bonding agent enables substrate bonding at lower temperatures compared to direct bonding, thereby reducing thermal damage and warping while maintaining the bonding function. The bonding agent acts as a mediator that facilitates the bonding process without requiring the substrates to be in direct contact at high temperatures.
2Strength
If elevated temperature heating is applied to form covalent bonds between substrates, then strong bonds are formed, but temperature-sensitive components experience thermal damage
Solution Approach 1:
The bonding process utilizes parameter changes by controlling the temperature profile and using a bonding agent that enables effective bonding at reduced temperatures. The bonding agent modifies the bonding parameters, allowing covalent bond formation at lower temperatures that do not damage temperature-sensitive components while still achieving strong bond strength.
3Productivity
If heating and cooling cycles are used to form direct bonds, then substrates are bonded together, but mismatches in coefficients of thermal expansion cause warping and thermal stress fractures
Solution Approach 1:
The bonding agent serves as an intermediary that compensates for mismatches in thermal expansion coefficients between substrates. During heating and cooling cycles, the bonding agent absorbs and distributes thermal stress, preventing warping and thermal stress fractures while maintaining substrate structural integrity and bonding efficiency.
4Reliability
If direct bonding is used to seal component packages, then hermetic sealing is achieved, but hermeticity is reduced due to warping and thermal stress fractures
Solution Approach 1:
The bonding process utilizes parameter changes by employing a bonding agent that enables effective hermetic sealing at lower temperatures. This approach maintains the hermetic sealing capability while reducing thermal stress and warping, thereby preserving both hermeticity and bond strength in the sealed component package.
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 process creates a hermetically sealed enclosure suitable for temperature-sensitive components, preventing thermal stress fractures and maintaining hermeticity, and can be used for a variety of electronic components including solar cells and implantable medical devices.
Implementation Method 1
the parameters of the laser bonding process, e.g., the wavelength of EM radiation, the substrate materials used, and intermediate layer materials used, may be selected such that the substrates are transparent to the EM radiation while the intermediate layer absorbs the EM radiation
Implementation Method 2
The heat generated in the intermediate layer due to the absorption of the EM radiation by the intermediate layer may fuse the two substrates together
Implementation Method 3
Electromagnetic (EM) radiation, e.g., output from a laser device, may then be directed through one of the substrates and onto the intermediate layer in order to heat the intermediate layer
Data Source
AI summary
A method includes depositing a thin film on a first surface of a first substrate and moving a second surface of a second substrate into contact with the thin film such that the thin film is located between the first and second surfaces. The method further includes generating electromagnetic (EM) radiation of a first wavelength, the first wavelength selected such that the thin film absorbs EM radiation at the first wavelength. Additionally, the method includes directing the EM radiation through one of the first and second substrates and onto a region of the thin film until the first and second substrates are fused in the region.