Elastic Wave Device Bonding Layer for Plate Wave Confinement
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Solution Overview
Problem
Elastic wave devices experience deterioration in characteristics due to bonding issues between the piezoelectric and supporting substrates with an acoustic reflector layer, affecting their performance.
Innovation Solution
Incorporating a bonding layer within the acoustic multilayer film, specifically between the acoustic impedance layers or at the interface between the acoustic multilayer film and the supporting substrate, to enhance the confinement of plate waves and stabilize the device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding layer is provided inside the acoustic multilayer film or at the interface between the acoustic multilayer film and the supporting substrate, then the possibility of deterioration of device characteristics is decreased, but the device structure becomes more complex
Solution Approach 1:
A bonding layer is introduced as an intermediary element between the piezoelectric substrate and the acoustic multilayer film, or within the acoustic multilayer film itself. This bonding layer serves as a mediator that improves the reliability of the elastic wave device by preventing characteristic deterioration, while its strategic placement minimizes the increase in overall structural complexity
Solution Approach 2:
The acoustic multilayer film is segmented into at least four acoustic impedance layers with alternating high and low acoustic impedances. This segmentation allows the bonding layer to be positioned at specific interfaces or within specific layers, optimizing both the reliability improvement and the management of structural complexity
2Reliability
If at least four acoustic impedance layers are used in the acoustic multilayer film, then plate wave confinement is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The acoustic multilayer film is designed with at least four acoustic impedance layers that have alternating high and low acoustic impedance values. This parameter-based design (varying acoustic impedance) effectively confines plate waves within the piezoelectric substrate, while the systematic alternation of layer types provides a manageable manufacturing approach
Solution Approach 2:
The acoustic multilayer film employs composite material structures with alternating high and low acoustic impedance layers. This composite approach achieves superior plate wave confinement by creating multiple acoustic impedance barriers, while the repetitive alternating pattern simplifies the manufacturing process compared to designing unique layer configurations
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 solution effectively reduces the likelihood of characteristic deterioration in elastic wave devices by efficiently confining plate waves and maintaining good impedance characteristics, even with varying numbers of acoustic impedance layers.
Implementation Method 1
The acoustic multilayer film includes at least four acoustic impedance layers. The at least four acoustic impedance layers include at least one low acoustic impedance layer and at least one high acoustic impedance layer having an acoustic impedance higher than the low acoustic impedance layer.
Implementation Method 2
a piezoelectric substrate on the acoustic multilayer film, and an IDT electrode on the piezoelectric substrate
Data Source
AI summary
An elastic wave device includes a supporting substrate, an acoustic multilayer film on the supporting substrate, a piezoelectric substrate on the acoustic multilayer film, and an IDT electrode on the piezoelectric substrate. The acoustic multilayer film includes at least four acoustic impedance layers. The at least four acoustic impedance layers include at least one low acoustic impedance layer and at least one high acoustic impedance layer having an acoustic impedance higher than the low acoustic impedance layer. The elastic wave device further includes a bonding layer provided at any position in a range of from inside the acoustic impedance layer, which is the fourth acoustic impedance layer from the piezoelectric substrate side towards the supporting substrate side, to an interface between the acoustic multilayer film and the supporting substrate.