Multilayer Film Substrate Bonding for Stable Acoustic Wave Devices
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Solution Overview
Problem
The bonding strength between piezoelectric substrates and support substrates in acoustic wave devices is inadequate, requiring improved bondability to enhance device performance.
Innovation Solution
A multilayer film substrate configuration is introduced, comprising a piezoelectric substrate, first and second insulating films, and a bonding layer between them, with the bonding layer's thickness optimized to improve adhesion while maintaining acoustic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a piezoelectric substrate is directly bonded to a support substrate, then the structure is simple, but the bonding strength is insufficient
Solution Approach 1:
The patent introduces insulating films and bonding layers as intermediary structures between the piezoelectric substrate and support substrate. The first insulating film is formed on the piezoelectric substrate, the second insulating film is formed on the support substrate, and a bonding layer is formed between these insulating films. This intermediary structure provides both mechanical bonding strength and electrical insulation, resolving the contradiction between simple structure and sufficient bonding strength.
Solution Approach 2:
The patent employs composite material structures by combining piezoelectric substrate, insulating films (such as silicon oxide or silicon nitride), and bonding layers (such as metal layers or dielectric layers with specific dielectric constants). This composite approach allows each layer to contribute its specific properties - the piezoelectric layer provides acoustic wave generation, the insulating films provide electrical isolation, and the bonding layers provide mechanical adhesion - thereby achieving strong bonding without excessive structural complexity.
2Strength
If insulating films and bonding layers are added to improve bondability, then bonding strength is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the insulating films on the piezoelectric substrate and support substrate before the bonding process. The first insulating film is formed on the piezoelectric substrate, and the second insulating film is formed on the support substrate in advance. This preliminary preparation ensures that the surfaces are properly conditioned for bonding, improving bondability while allowing the bonding process itself to remain relatively simple.
Solution Approach 2:
The patent utilizes parameter changes by controlling the thickness, dielectric constant, and material composition of the insulating films and bonding layers. By optimizing parameters such as the dielectric constant of the bonding layer and the thickness ratios of various layers, the patent achieves strong bonding and desired acoustic performance without requiring excessively complex manufacturing processes. The parameters are tuned to balance manufacturing ease with performance requirements.
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 configuration significantly enhances the bondability between the piezoelectric and support substrates, reducing variations in resonance and anti-resonance frequencies and maintaining the performance of the acoustic wave device.
Implementation Method 1
a piezoelectric substrate
Data Source
AI summary
A multilayer film substrate includes a piezoelectric substrate, a first insulating film formed on the piezoelectric substrate, a support substrate, a second insulating film formed on the support substrate, and a bonding layer formed between the first insulating film and the second insulating film. The piezoelectric substrate and the support substrate are bonded each other using the first insulating film, the second insulating film, and the bonding layer as an interlayer.