Argon Amorphous Layer Joins Piezoelectric and Silicon Substrates
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Solution Overview
Problem
Composite substrates used in SAW devices face issues with low adhesion strength between piezoelectric and support substrates, leading to peeling during high-temperature processes.
Innovation Solution
A composite substrate with a single-crystal lithium tantalate or lithium niobate piezoelectric substrate and a single-crystal silicon support substrate joined by an amorphous layer containing 3 to 14 atomic percent of argon, with a preferred three-layer structure where the third layer is thicker than the first and second layers, providing enhanced adhesion strength and heat resistance up to 400°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If organic-inorganic composite substrates are used to improve flexibility and conformability to curved surfaces, then adaptability is improved, but manufacturing complexity increases due to multi-layer structure requirements
Solution Approach 1:
The patent employs an organic-inorganic composite substrate structure combining an inorganic substrate layer with an organic functional layer. This composite material approach enables the substrate to achieve both mechanical flexibility for conformability to curved surfaces and the necessary structural stability, while the integrated layer design manages complexity through functional specialization of each layer type.
Solution Approach 2:
The substrate is divided into distinct functional layers: an inorganic substrate layer providing mechanical support and flexibility, and an organic functional layer containing the light-emitting elements. This segmentation allows each layer to be optimized independently for its specific function, enabling conformability to curved surfaces while managing manufacturing complexity through modular layer design.
2Strength
If rigid substrates are used to maintain structural stability, then strength is improved, but flexibility and conformability to curved surfaces deteriorate
Solution Approach 1:
The patent uses a composite substrate system where the inorganic substrate layer provides structural stability and strength, while the organic functional layer contributes flexibility. This composite approach resolves the contradiction by distributing mechanical properties across different material layers, allowing the overall structure to be both strong and flexible enough for curved surface applications.
Solution Approach 2:
Different regions of the substrate structure are assigned different mechanical properties: the inorganic substrate layer is designed with high structural stability for strength, while the organic functional layer provides flexibility. This local differentiation of material properties allows the substrate to simultaneously achieve both structural integrity and adaptability to curved surfaces.
3Adaptability or versatility
If multiple functional layers are integrated to improve device functionality, then adaptability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The device is segmented into distinct functional layers with clear interfaces: inorganic substrate layer, organic functional layer, and encapsulation layers. This segmentation strategy improves manufacturability by allowing each layer to be processed and quality-checked independently, reducing the overall manufacturing precision requirements compared to monolithic structures while maintaining enhanced device functionality.
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 amorphous layer with 3 to 14 atomic percent argon significantly improves adhesion strength and heat resistance, preventing peeling during high-temperature processes, and maintains low iron content to avoid contamination.
Implementation Method 1
an amorphous layer joining together the piezoelectric substrate and the support substrate, wherein the amorphous layer contains 3 to 14 atomic percent of Ar
Data Source
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AI summary
A composite substrate according to the present invention includes a piezoelectric substrate that is a single-crystal lithium tantalate or lithium niobate substrate, a support substrate that is a single-crystal silicon substrate, and an amorphous layer joining together the piezoelectric substrate and the support substrate. The amorphous layer contains 3 to 14 atomic percent of argon. The amorphous layer includes, in order from the piezoelectric substrate toward the composite substrate, a first layer, a second layer, and a third layer. The first layer contains a larger amount of a constituent element (such as tantalum) of the piezoelectric substrate than the second and third layers. The third layer contains a larger amount of a constituent element (silicon) of the support substrate than the first and second layers. The second layer contains a larger amount of argon than the first and third layers.