Acoustic Wave Resonator Layout for Lower Edge Scattering
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Solution Overview
Problem
Existing acoustic wave devices suffer from high energy scattering and loss due to large acoustic discontinuities between the IDT electrode and reflector electrodes, leading to increased energy leakage.
Innovation Solution
The introduction of dielectric films extending from the edge regions of the IDT electrode to the outer sides of the reflector electrodes, reducing acoustic discontinuity and minimizing energy scattering by adjusting acoustic velocities in the edge regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a dielectric film is provided between the IDT electrode and piezoelectric film in the edge regions, then acoustic discontinuity is reduced and energy scattering decreases, but device complexity increases
Solution Approach 1:
The dielectric film is selectively provided only in the first and second edge regions of the IDT electrode, not uniformly across the entire electrode structure. This local modification reduces acoustic discontinuity and energy scattering at the critical edge regions where acoustic waves propagate toward the reflector electrodes, while maintaining the simplicity of the overall device structure.
2Reliability
If the dielectric film extends beyond the reflector electrodes to outer regions, then acoustic wave scattering is minimized and reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The dielectric film is designed to extend in advance from the edge regions of the IDT electrode to the outer sides of the reflector electrodes, creating a preliminary acoustic transition zone before the acoustic waves reach the reflector electrodes. This preliminary action of the dielectric film prepares the acoustic path by gradually changing acoustic velocity, preventing sudden acoustic discontinuities and reducing scattering at the reflector electrode boundaries, thereby improving reliability.
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 design results in reduced energy loss and improved reliability by minimizing acoustic wave scattering and crack formation during stress tests, while maintaining efficient acoustic wave propagation.
Implementation Method 1
adjusting acoustic velocities in the edge regions
Implementation Method 2
a piezoelectric substrate, an interdigital (IDT) electrode on or above the piezoelectric substrate
Data Source
AI summary
An acoustic wave device includes an IDT electrode and reflector electrodes on or above a piezoelectric substrate. A region in which first and second electrode fingers of the IDT electrode overlap each other in an acoustic wave propagation direction defines an intersection region. The intersection region includes a center region and first and second edge regions on both sides of the center region. Dielectric films extend from the first and second edge regions to outer side regions in the acoustic wave propagation direction of the reflector electrodes via the reflector electrodes.