Free-Standing Solid State Layers via Thermal Fracture
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Solution Overview
Problem
Conventional microelectronic substrates, such as silicon wafers, often have excess thickness that increases costs without providing corresponding benefits in microfabrication applications, as they do not meet the specific requirements of advanced microfabrication processes like solar cells and photovoltaic systems.
Innovation Solution
A method involving the formation of a polymer layer on a solid state material with a different thermal expansion coefficient, followed by thermal processing to induce fracture and produce free-standing layers, allowing for repeated cycling with minimal material loss and efficient production of thin layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thick substrates are used, then mechanical strength and structural stability are ensured, but material cost increases and microfabrication efficiency decreases
Solution Approach 1:
The patent applies segmentation by dividing a thick substrate into multiple thin free-standing layers through controlled fracture. The substrate is segmented into discrete layers that can be used individually, converting one thick substrate into multiple usable thin layers and reducing material waste.
Solution Approach 2:
The patent changes the thickness parameter of the substrate from thick to thin by inducing controlled fracture. This parameter change is achieved through thermal processing that creates stress differences, allowing the substrate to fracture into thin layers that meet microfabrication requirements while minimizing material waste.
2Strength
If conventional thick substrates are used, then structural integrity is maintained, but production cost increases
Solution Approach 1:
The patent segments the thick substrate into multiple thin layers, allowing each layer to be used as a separate structural component. This segmentation enables the production of multiple devices from one substrate, reducing the cost per device while maintaining the structural integrity needed for each individual layer.
Solution Approach 2:
The patent recovers value from the substrate by fracturing it into multiple usable thin layers rather than discarding excess material. Each fractured layer retains sufficient structural integrity for microfabrication applications, allowing the original substrate to serve multiple purposes and reducing overall production costs.
3Loss of substance
If substrate thickness is reduced to meet application requirements, then material efficiency improves, but structural stability may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-processing the substrate through thermal treatment before fracture. This thermal processing creates controlled stress distributions that enable the substrate to fracture into thin layers while maintaining structural stability, allowing material efficiency to improve without compromising reliability.
Solution Approach 2:
The patent changes physical parameters through thermal processing to enable the substrate to achieve both thin thickness and structural stability. The thermal treatment modifies the stress state and mechanical properties, allowing the substrate to fracture into thin layers that maintain sufficient structural integrity for microfabrication applications.
4Productivity
If multiple thin layers are produced from one substrate, then productivity increases, but process complexity increases
Solution Approach 1:
The patent merges multiple operations into a single integrated process: thermal processing, stress induction, and controlled fracture are combined into one sequence that produces multiple thin layers simultaneously. This merging approach increases productivity while managing process complexity by coordinating multiple functions within a unified workflow.
Solution Approach 2:
The patent utilizes phase transitions in the thermal processing step to enable controlled fracture. By heating and cooling the substrate through specific temperature ranges, the material undergoes thermal stress that leads to controlled fracturing into multiple layers, achieving high productivity through a physics-based mechanism rather than multiple mechanical processing steps.
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 enables the production of a large number of thin, high-quality free-standing solid state layers with minimal material loss, reducing costs and enhancing the efficiency of microfabrication processes by allowing multiple cycles of layer production without the need for custom equipment or extensive manual effort.
Implementation Method 1
a layer of polymer is formed on the available surface. The solid state material and polymer layer are then exposed to a change in local temperature from a first temperature to a second temperature below the first temperature to cause the solid state material to fracture
Implementation Method 2
The polymer is characterized by a second thermal expansion coefficient that is at least about 50 × 10^-6 greater than the first thermal expansion coefficient of the solid state material
Data Source
Figure 1A~1D
Figure 2~3
AI summary
In a method for producing a free-standing solid state layer, a solid state material is provided having at least one surface available for layer formation thereon and a layer of polymer is formed on the available surface. The solid state material and polymer layer are then exposed to a change in local temperature from a first temperature that is about room temperature to a second temperature to cause the solid state material to fracture along a plane at a depth in the material, to produce at least one free-standing solid state layer from the solid state material.