Heterostructure Bonding via Trenches Filled with Intermediate Thermal Expansion Material
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Solution Overview
Problem
The assembly of substrates with different thermal expansion coefficients leads to stress and deformation issues during temperature changes, resulting in reduced bond quality and potential substrate breakage, particularly at elevated temperatures.
Innovation Solution
Forming trenches on the bonding surfaces of the substrates and filling them with a material having a thermal expansion coefficient between the two substrates, which localizes the thermal expansion coefficient match and reduces strain, thereby enhancing bonding energy and reducing defectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If two substrates with different thermal expansion coefficients are bonded together, then a heterostructure is formed with potential for high-temperature processing, but thermal stresses and deformations increase during temperature rises
Solution Approach 1:
The patent introduces intermediate layers with specific thermal expansion coefficients at the bonding interface between substrates. These intermediate layers are placed locally at the interface region to provide gradual thermal expansion transition, reducing stress concentration at the bonding interface while maintaining the overall heterostructure configuration.
Solution Approach 2:
The patent employs intermediate layers as mediator materials between the two substrates with different thermal expansion coefficients. These intermediate layers act as a buffer zone that gradually transitions the thermal expansion properties, preventing direct stress transmission between the dissimilar substrates during temperature changes.
2Strength
If temperature is increased to reinforce bonding interface, then bond strength is improved, but substrate breakage risk increases due to stress relaxation
Solution Approach 1:
The intermediate layers are specifically positioned at the bonding interface region to provide localized stress management. This allows the bonding interface to be strengthened through high-temperature processing while the intermediate layers locally absorb and distribute thermal stresses, preventing stress concentration that would lead to substrate breakage.
Solution Approach 2:
The intermediate layers are pre-installed at the bonding interface before final bonding and high-temperature processing. These layers serve as pre-positioned cushioning elements that anticipate and mitigate thermal stress during subsequent temperature rises, protecting the substrates from stress-induced failure while allowing bond strengthening.
3Adaptability or versatility
If substrates with different thermal expansion coefficients are assembled, then heterostructure functionality is achieved, but deformations and delamination occur during heat treatments
Solution Approach 1:
The intermediate layers are strategically placed at the bonding interface to provide localized thermal expansion matching. This allows the heterostructure to maintain its functional benefits from dissimilar substrates while the intermediate layers locally stabilize the interface region, preventing delamination and maintaining structural integrity during heat treatments.
Solution Approach 2:
The patent creates a composite structure consisting of two dissimilar substrates bonded through intermediate layers. This composite configuration combines the functional advantages of different materials while the intermediate layers provide thermal expansion compatibility, resulting in a stable heterostructure that maintains both functionality and structural integrity under thermal processing.
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 effectively minimizes thermal stresses and deformations between substrates during heat treatments, improving the bond quality and uniformity, and traps defect sources like bubbles at the interface, leading to a more robust heterostructure.
Implementation Method 1
bonding at least one first substrate having a first thermal expansion coefficient onto a second substrate having a second thermal expansion coefficient, the first thermal expansion coefficient being different from the second thermal expansion coefficient
Implementation Method 2
motifs having an elasticity in the plane of assembly of the substrates are produced on one of the two substrates in order to absorb thermoelastic strains in the assembly during temperature rises
Data Source
AI summary
A method of producing a heterostructure by bonding at least one first substrate having a first thermal expansion coefficient onto a second substrate having a second thermal expansion coefficient, with the first thermal expansion coefficient being different from the second thermal expansion coefficient. Prior to bonding, trenches are formed in one of the two substrates from the bonding surface of the substrate. The trenches are filled with a material having a third thermal expansion coefficient lying between the first and second thermal expansion coefficients.