Bulk Acoustic Wave Resonator Gap Structure for Parasitic Resonance
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Solution Overview
Problem
Current bulk acoustic wave resonators face challenges in reducing parasitic resonance and improving the quality factor (Q value), which affects the performance of communication devices, especially in high-frequency applications where signal selectivity and insertion loss are critical.
Innovation Solution
A bulk acoustic wave resonance structure is designed with a substrate, reflection structure, first and second electrodes, and a piezoelectric layer, where first gaps are created between the piezoelectric layer and second sub-electrodes, increasing the distance between electrodes to reduce electric field intensity and suppress parasitic resonance, thereby enhancing the Q value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between electrodes is reduced to miniaturize the device, then the device size is reduced, but the electric field intensity increases causing parasitic resonance
Solution Approach 1:
The patent applies local quality by creating gaps only in specific regions where parasitic resonance occurs, rather than uniformly increasing the distance between electrodes throughout the entire structure. This allows miniaturization in non-critical areas while suppressing parasitic resonance in critical regions through localized gap formation.
Solution Approach 2:
The electrode structure is segmented into multiple sub-electrodes with gaps between them, transforming a continuous electrode into a distributed array. This segmentation reduces the continuous electric field into discrete fields, thereby suppressing parasitic resonance while maintaining overall compact dimensions.
2Object-generated harmful factors
If gaps are added between electrodes to reduce parasitic resonance, then parasitic resonance is suppressed, but the device complexity increases
Solution Approach 1:
The gap formation process is merged with the existing electrode fabrication工艺流程, utilizing the same lithography and etching steps to create both the electrode patterns and the gaps. This integration minimizes additional process complexity while achieving parasitic resonance suppression.
3Reliability
If the electric field intensity is reduced to suppress parasitic resonance, then the Q value is improved, but the signal strength decreases
Solution Approach 1:
The electric field intensity is reduced only in specific regions where parasitic resonance occurs, while maintaining high field intensity in the central resonance region. This selective field distribution improves Q value by suppressing parasitic modes while preserving signal strength in the primary resonance mode.
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 structure effectively reduces parasitic resonance and improves the Q value of the bulk acoustic wave resonator, leading to better signal selectivity and reduced insertion loss, particularly in high-frequency communication applications.
Implementation Method 1
a piezoelectric layer and a second electrode that are sequentially located on the substrate; and first gaps. The first electrode includes a first sub-electrode located in a first region and second sub-electrodes located in a second region outside the first region. The piezoelectric layer in the first region is in direct contact with the first sub-electrode and the second electrode
Data Source
AI summary
A bulk acoustic wave resonant structure and a preparation method therefor, and an acoustic wave device are provided. The bulk acoustic wave resonant structure includes: a substrate; a reflection structure, a first electrode, a piezoelectric layer and a second electrode, which are successively located on the substrate, wherein the first electrode comprises a first sub-electrode located in a first region and a second sub-electrode located in a second region other than the first region, and the piezoelectric layer respectively comes into direct contact with the first sub-electrode and the second electrode in the first region; and a first gap, which is located between the piezoelectric layer and the second sub-electrode, wherein an orthographic projection of the first gap on the substrate surrounds the first region.