Stepped BAW Resonator Electrode Layout for Lower Parasitic Resonance
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Solution Overview
Problem
The challenge in improving the performance of bulk acoustic wave resonators lies in reducing parasitic resonance and enhancing the quality factor (Q value) to meet the demands of miniaturization and integration in communication devices, particularly in the context of 5G communication where signal selectivity and reduced insertion loss are crucial.
Innovation Solution
The solution involves designing a bulk acoustic wave resonance structure with a first electrode having multiple slopes and gaps, which increases the distance between electrodes in non-resonance regions, thereby reducing electric field intensity and minimizing parasitic resonance, while incorporating a piezoelectric layer to convert electrical signals into acoustic waves and a reflection structure to confine acoustic wave energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between electrodes in non-resonance regions is increased to reduce parasitic resonance, then the quality factor (Q value) is improved, but the device area increases
Solution Approach 1:
The first electrode is designed with a three-dimensional stepped structure having different heights in different regions. The first portion has a first height, the second portion has a second height greater than the first height, and the third portion has a third height less than the second height. This vertical dimensionality change allows the electrode to extend into the thickness direction of the piezoelectric layer, effectively increasing the electrode area and reducing electric field intensity without increasing the planar footprint of the device.
Solution Approach 2:
The stepped structure of the first electrode creates nested regions where portions of the electrode are positioned at different vertical levels within the piezoelectric layer thickness. This nesting approach maximizes the use of available space in the vertical dimension, allowing the electrode to occupy multiple height levels while maintaining a compact planar configuration.
2Object-generated harmful factors
If a stepped structure with multiple heights is used to reduce electric field intensity, then parasitic resonance is minimized, but the manufacturing complexity increases
Solution Approach 1:
The stepped structure of the first electrode is formed during the initial electrode fabrication process using standard photolithography and etching techniques. By pre-forming the multi-height structure in the electrode layer before assembling the complete resonator, the complex geometry is created as part of the base manufacturing flow rather than requiring additional complex processing steps later in the fabrication sequence.
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 enhances the Q value by 10% to 20%, improving signal selectivity and reducing insertion loss, thus supporting the miniaturization and integration of bulk acoustic wave resonators in high-frequency communication devices.
Implementation Method 1
incorporating a piezoelectric layer to convert electrical signals into acoustic waves
Data Source
AI summary
Provided in the embodiments of the present disclosure are a bulk acoustic wave resonant structure and a preparation method therefor, and an acoustic wave device. The bulk acoustic wave resonant structure comprises: a substrate; and a reflection structure, a first electrode, a piezoelectric layer and a second electrode which are sequentially located on the substrate, wherein an overlapping region of an orthographic projection of the first electrode on the substrate, an orthographic projection of the piezoelectric layer on the substrate and an orthographic projection of the second electrode on the substrate is a first overlapping region; the first electrode comprises a first portion, a second portion and a third portion, the second portion being connected to the first portion and the third portion; an orthographic projection of the first portion on the substrate falls within the first overlapping region, and the first portion extends in a direction parallel to a surface of the substrate; an orthographic projection of the second portion on the substrate and an orthographic projection of the third portion on the substrate fall within a region outside the first overlapping region, the second portion has an inclination angle relative to the surface of the substrate, and the third portion extends in a direction parallel to the surface of the substrate; and the first portion is higher than the third portion in a direction perpendicular to the surface of the substrate.