Boundary Acoustic Wave Structure for Post-Fabrication Frequency Tuning
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Solution Overview
Problem
There is no effective method for adjusting the frequency characteristics of boundary acoustic wave devices after manufacturing, as the traditional methods used for surface acoustic wave devices are not applicable due to the embedded IDT electrode at the interface between the first and second solid media in boundary acoustic wave devices.
Innovation Solution
A method for manufacturing boundary acoustic wave devices involves preparing a laminated structure with an IDT electrode at the interface between the first and second media, and externally providing energy to reform the media to adjust the frequency, using a reform medium layer that can be easily reformed by energy, such as a femtosecond laser beam, to concentrate energy within a specific distance from the interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the IDT electrode is embedded at the interface between first and second solid media in a boundary acoustic wave device, then the device structure is simplified and compactness is improved, but the ability to adjust frequency characteristics after manufacturing is lost
Solution Approach 1:
The patent divides the second solid media into multiple layers, including a reform medium layer that can be selectively modified. This segmentation allows frequency adjustment without affecting the embedded IDT electrode structure, resolving the contradiction between structural simplicity and adjustability.
Solution Approach 2:
The reform medium layer acts as an intermediary between the laser beam energy and the boundary acoustic wave propagation characteristics. By modifying this intermediate layer through laser irradiation, the frequency characteristics can be adjusted without directly altering the IDT electrode or the overall device structure.
2Adaptability or versatility
If traditional frequency adjustment methods are used on surface acoustic wave devices with exposed IDT electrodes, then frequency can be adjusted after manufacturing, but the device requires additional space and has a complex package structure
Solution Approach 1:
Instead of adjusting frequency by modifying the IDT electrode or adding components above it (traditional method), the patent inverts the approach by adjusting frequency through modifying the second solid media layer below and around the embedded IDT electrode. This eliminates the need for additional space and simplifies the package structure.
3Manufacturing precision
If energy is externally provided to reform the first and second media to adjust frequency, then frequency characteristics can be precisely adjusted after manufacturing, but the energy must be concentrated within a specific distance from the interface
Solution Approach 1:
The patent applies local quality by making only the reform medium layer (a specific portion of the second solid media) susceptible to laser-induced reforming, while other layers remain unchanged. This localized approach allows precise frequency adjustment without requiring complex energy distribution control throughout the entire device.
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 approach allows for precise and reliable adjustment of frequency characteristics in boundary acoustic wave devices, reducing variations and enabling the production of devices with stable and uniform frequency performance without increasing manufacturing complexity or cost.
Implementation Method 1
When the surface acoustic wave device 501 is irradiated with a laser beam emitted from thereabove using a laser apparatus 507, the laser beam transmits through the cap member 504. Accordingly, the substance 506 is heated by the laser beam, vaporized, and deposited on the IDT electrode 503 positioned therebelow.
Implementation Method 2
externally providing energy capable of reaching the inside of the first medium and/or the second medium to a laminated structure in which an interdigital transducer (IDT) electrode is arranged at an interface between the first medium and the second medium and utilizes a boundary acoustic wave that propagates through the interface
Data Source
AI summary
A boundary acoustic wave device includes a first medium, a second medium laminated on the first medium, and an IDT electrode arranged at an interface between the first medium and the second medium. The boundary acoustic wave device further includes a reformed portion disposed in at least one of the first medium and the second medium, reformed by externally provided energy, and having frequency characteristics different from frequency characteristics exhibited when the boundary acoustic wave device includes only at least one of the first medium and the second medium.