Bulk Acoustic Wave Resonator Structure for Lateral Wave Reflection
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Solution Overview
Problem
Bulk acoustic wave resonators experience energy leakage and heat generation due to acoustic impedance mismatch and lateral mode acoustic waves, affecting device reliability.
Innovation Solution
A bulk acoustic wave resonator design featuring a stacked structure with cavities and support columns that form acoustic reflection structures to reflect lateral acoustic waves, improving quality factor and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If alternating current is applied to an electrode of the bulk acoustic wave resonator, then longitudinal vibration is generated and acoustic wave propagates towards the thickness direction, but lateral mode acoustic waves are excited simultaneously due to acoustic impedance mismatch and non-uniform electric field, resulting in energy leakage
Solution Approach 1:
The resonator structure is segmented by introducing cavities and support columns that divide the resonator into distinct regions. The cavities are configured to reflect lateral acoustic waves, creating acoustic isolation zones that prevent energy leakage while maintaining the overall resonator functionality.
Solution Approach 2:
Different regions of the resonator are given different structural qualities - the cavities have specific geometries and positions optimized for acoustic reflection, while the support columns provide localized mechanical support. This local optimization addresses the acoustic impedance mismatch at specific locations without redesigning the entire structure.
2Reliability
If alternating current is applied to an electrode of the bulk acoustic wave resonator, then longitudinal vibration is generated, but heat is generated inside of the resonator due to energy loss, which greatly affects the reliability of a device
Solution Approach 1:
The cavities that were introduced to solve the energy leakage problem also serve as heat management structures. By reflecting lateral acoustic waves and reducing energy loss, they decrease the conversion of acoustic energy to heat, thereby lowering operating temperature and improving device reliability.
3Manufacturing precision
If cavities and support columns are added to reflect lateral acoustic waves, then quality factor is improved and heat dissipation is enhanced, but structural complexity and manufacturing difficulty increase
Solution Approach 1:
The cavities and support columns are designed and positioned in advance during the fabrication process to achieve the desired acoustic reflection properties. The structural parameters are predetermined to ensure the correct acoustic impedance matching and wave reflection characteristics, simplifying the manufacturing process by eliminating the need for post-fabrication adjustments.
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 design reduces energy leakage and enhances structural stability, improving the resonator's quality factor and heat dissipation capabilities.
Implementation Method 1
After alternating current is applied to an electrode of the bulk acoustic wave resonator, longitudinal vibration is mainly generated, that is, an acoustic wave propagates towards the thickness direction of a piezoelectric layer
Implementation Method 2
a first cavity located between the upper conductive layer and the piezoelectric layer is disposed outside the overlapping region, a plurality of first support columns are disposed in the first cavity, the plurality of first support columns are supported between the piezoelectric layer and the upper conductive layer
Data Source
AI summary
The present disclosure provides a bulk acoustic wave resonator and a manufacturing method thereof, and relates to the technical field of resonators. The bulk acoustic wave resonator includes a substrate, and a lower conductive layer, a piezoelectric layer and an upper conductive layer, which are sequentially disposed on the substrate in a stacked manner, wherein the lower conductive layer, the piezoelectric layer and the upper conductive layer have an overlapping region in a stacking direction, a first cavity located between the upper conductive layer and the piezoelectric layer is disposed outside the overlapping region, a plurality of first support columns are disposed inside the first cavity, the plurality of first support columns are supported between the piezoelectric layer and the upper conductive layer, the plurality of first support columns divide the first cavity into a plurality of through holes.