Acoustic Wave Resonator Layout for Lower Energy Leakage
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Solution Overview
Problem
Leakage of acoustic wave energy in the direction of extension of electrode fingers degrades the Q factor in existing acoustic wave devices.
Innovation Solution
The acoustic wave device incorporates a support with a hollow adjacent to the piezoelectric layer, through holes in the piezoelectric layer, and a configuration that utilizes first-order thickness shear mode bulk waves without reflectors, allowing for improved Q factor and reduced energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional acoustic wave device structure is used, then device simplicity is maintained, but acoustic wave energy leakage occurs in the direction of electrode finger extension degrading Q factor
Solution Approach 1:
The device is segmented into distinct functional regions: a first region with interdigital transducer electrodes for acoustic wave generation, and a second region with reflector electrodes for wave reflection. This segmentation confines acoustic wave energy within the piezoelectric layer, preventing leakage in the electrode finger extension direction and improving Q factor while maintaining reasonable structural complexity
Solution Approach 2:
The invention transitions from a one-dimensional electrode finger arrangement to a two-dimensional configuration by adding reflector electrodes perpendicular to the interdigital transducer electrodes. This dimensional change creates a closed acoustic wave path within the piezoelectric layer, eliminating energy leakage without significantly increasing overall device complexity
2Ease of manufacture
If number of electrode pairs is reduced to simplify device, then manufacturing is easier, but resonance characteristics deteriorate due to insufficient acoustic wave excitation
Solution Approach 1:
The reflector electrodes are positioned specifically at the ends of the interdigital transducer electrodes, creating localized reflection zones. This local quality enhancement allows effective acoustic wave confinement and resonance with fewer electrode pairs, simultaneously improving ease of manufacture while maintaining reliable resonance characteristics
Solution Approach 2:
The reflector electrodes create continuous acoustic wave reflection along with the interdigital transducer electrodes, forming a closed-loop acoustic path. This continuous action maintains effective resonance characteristics even with reduced electrode pairs, balancing manufacturing simplicity with performance reliability
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 solution enhances the Q factor by minimizing energy leakage and spurious emission, enabling effective excitation of first-order thickness shear mode bulk waves even with reduced electrode pairs, thus maintaining resonance characteristics.
Implementation Method 1
a piezoelectric layer extending in the first direction of the support, and an interdigital transducer electrode extending in the first direction of the piezoelectric layer
Data Source
AI summary
An acoustic wave device includes a support with a thickness in a first direction, a piezoelectric layer in the first direction, and an interdigital transducer electrode in the first direction with first electrode fingers in a second direction, a first busbar electrode connected to the first electrode fingers, second electrode fingers in the second direction and facing corresponding ones of the first electrode fingers in a third direction, and a second busbar electrode connected to the second electrode fingers. The support has a hollow adjacent to the piezoelectric layer and at least partially overlapping the interdigital transducer electrode. The piezoelectric layer has a first through hole penetrating the piezoelectric layer between at least one first electrode finger and the second busbar electrode. The first through hole communicates with the hollow, has a length in the third direction, and overlaps a portion of a second electrode finger.