Acoustic Wave Element Thinning for High-Q Miniaturization
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Solution Overview
Problem
Existing acoustic wave devices face challenges in miniaturization, leading to a decrease in Q value and increased propagation loss due to the need for reflectors and electrode configurations that hinder size reduction.
Innovation Solution
The development of acoustic wave elements with a support substrate thickness of 250 μm or less, a piezoelectric material layer, and a functional electrode configuration that utilizes a bulk wave in the thickness-shear mode, eliminating the need for reflectors and optimizing electrode spacing to maintain high Q values even with reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the acoustic wave device is miniaturized by reducing support substrate thickness, then the device size is reduced, but the Q value decreases and propagation loss increases
Solution Approach 1:
The invention changes the physical parameters of the support substrate, specifically reducing its thickness to 250 μm or less, which enables miniaturization while maintaining acoustic wave propagation characteristics. This parameter change allows the device to achieve compact size without significant degradation in Q value or increase in propagation loss.
Solution Approach 2:
The invention applies different surface roughness characteristics to different surfaces of the support substrate. The first surface (contacting piezoelectric material) has controlled roughness to ensure proper bonding and acoustic coupling, while the second surface has rougher texture that may help with acoustic wave confinement. This local differentiation of surface properties optimizes performance in the miniaturized device.
2Volume of moving object
If the support substrate thickness is reduced to miniaturize the device, then the device size is reduced, but propagation loss increases
Solution Approach 1:
By optimizing the support substrate thickness parameter to 250 μm or less, the invention achieves a balance between miniaturization and maintaining low propagation loss. This specific thickness parameter enables compact device size while preserving sufficient mechanical strength and acoustic wave propagation efficiency.
Solution Approach 2:
The invention utilizes a thin support substrate that functions as a flexible yet structurally sound component. The thin film approach allows for device miniaturization while the carefully controlled thickness ensures adequate mechanical support and minimal acoustic energy loss during propagation.
3Reliability
If reflectors and electrode configurations are added to maintain Q value, then the Q value is maintained, but the device size increases
Solution Approach 1:
The invention extracts or eliminates the need for separate reflector components by integrating acoustic wave confinement directly into the support substrate structure. The support substrate itself, with its optimized thickness and surface properties, provides the necessary acoustic boundaries without requiring additional reflector elements, thereby maintaining Q value while reducing overall device size.
Solution Approach 2:
The support substrate serves multiple functions simultaneously: it provides mechanical support, enables acoustic wave propagation, and acts as an acoustic boundary without requiring separate reflector components. This multi-functionality allows the device to maintain high Q values while achieving miniaturization by eliminating redundant structural elements.
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 allows for the miniaturization of acoustic wave devices without a significant drop in Q value or increase in propagation loss, achieving favorable resonance characteristics and a wider fractional bandwidth.
Implementation Method 1
a piezoelectric material layer on the first surface, and a functional electrode on the piezoelectric material layer, wherein a surface roughness of the second surface is rougher than a surface roughness of the piezoelectric material layer
Data Source
AI summary
A method for manufacturing an acoustic wave element including a support substrate, a piezoelectric material layer on the support substrate, and a functional electrode on the piezoelectric material layer, includes preparing a wafer in which the support substrate and the piezoelectric material layer are laminated, thinning the support substrate of the wafer, and after the thinning the support substrate, cutting the wafer with a dicing machine to singulate the acoustic wave element.