Bonded Acoustic Wave Element with Low-Resistance Spurious Damping
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Solution Overview
Problem
Portable terminal devices require acoustic wave elements with improved electrical characteristics to reduce signal leakage and enhance communication quality, particularly in specified frequency bands.
Innovation Solution
An acoustic wave element is designed with an IDT electrode on a piezoelectric crystal substrate, bonded to a supporting substrate, featuring a low resistance region with a sheet resistance of 5×10^3Ω to 5×10^7Ω, which suppresses bulk wave spurious emission by controlling the sheet resistance value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a composite substrate is used with a piezoelectric substrate and support substrate, then electrical characteristics are improved, but signal leakage to adjacent channels increases
Solution Approach 1:
The patent introduces a low resistance region with specific sheet resistance (5×10³Ω to 5×10⁷Ω) at the lower surface of the piezoelectric substrate to selectively suppress bulk wave spurious emission. This local modification of electrical properties addresses signal leakage in specific frequency bands without compromising the overall electrical characteristics improved by the composite substrate structure.
Solution Approach 2:
The patent controls the sheet resistance of the low resistance region within a specific range (5×10³Ω to 5×10⁷Ω) to optimize the attenuation of bulk wave spurious emission. By adjusting this electrical parameter, the invention achieves reduced signal leakage to adjacent channels while maintaining the electrical performance benefits of the composite substrate.
2Object-generated harmful factors
If the sheet resistance of the low resistance region is too low, then bulk wave spurious emission is suppressed, but manufacturing precision becomes difficult to control
Solution Approach 1:
The patent defines a specific sheet resistance range (5×10³Ω to 5×10⁷Ω) for the low resistance region that balances spurious emission suppression with manufacturability. This parameter optimization ensures that the beneficial effect of bulk wave attenuation is achieved while maintaining reasonable manufacturing precision and process control.
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 configuration enhances electrical characteristics and attenuates bulk wave spurious emission, improving the acoustic wave element's performance and reducing signal leakage in specific frequency bands.
Implementation Method 1
The IDT electrode includes a plurality of electrode fingers and excites a surface acoustic wave. The first substrate includes an upper surface on which the IDT electrode is located and is configured by a piezoelectric crystal.
Implementation Method 2
either of a first region which continues from the lower surface of the first substrate toward a side where the upper surface is located or a second region which continues from the lower surface of the first substrate toward a side where the second substrate is located is a low resistance region having a sheet resistance of 5×10³Ω to 5×10⁷Ω
Data Source
AI summary
An acoustic wave element includes an IDT electrode including a plurality of electrode fingers and exciting a surface acoustic wave, a first substrate including an upper surface on which the IDT electrode is located, the first substrate being configured by a piezoelectric crystal, and a second substrate bonded to a side where a lower surface of the first substrate is located. Either of a first region which continues from the lower surface of the first substrate toward a side where the upper surface is located or a second region which continues from the lower surface of the first substrate toward a side where the second substrate is located is a low resistance region having a resistance value of 5×103Ω to 5×107Ω.