Acoustic Wave Resonator Layout for Q Factor and Leakage Control
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Solution Overview
Problem
The Q factor of acoustic wave devices is degraded due to leakage of acoustic wave energy in the direction of extension of electrode fingers, as seen in existing acoustic wave devices.
Innovation Solution
The acoustic wave device incorporates a support with a hollow adjacent to the piezoelectric layer, overlapping the interdigital transducer electrode, and features through holes in the piezoelectric layer between electrode fingers and busbar electrodes, which communicate with the hollow, reducing energy leakage and spurious emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic wave energy is allowed to propagate freely in the direction of electrode finger extension, then the device can operate, but energy leakage occurs and Q factor degrades
Solution Approach 1:
The patent extracts and removes the harmful acoustic wave energy that leaks in the direction of electrode finger extension by providing through holes that allow this specific energy to escape through the piezoelectric layer to the hollow space, while maintaining normal device operation
Solution Approach 2:
The patent converts the harmful acoustic wave energy leakage into a beneficial feature by designing through holes that deliberately allow controlled energy escape paths, transforming what was previously unwanted energy loss into a mechanism that prevents more significant energy loss and improves Q factor
2Reliability
If the device structure is simplified without through holes, then manufacturing is easier, but spurious emission increases and Q factor decreases
Solution Approach 1:
The patent segments the piezoelectric layer by introducing through holes that divide the continuous structure into regions separated by these holes, creating specific pathways that control acoustic wave propagation and reduce spurious emission without overly complicating the overall device architecture
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 configuration enhances the Q factor by minimizing energy loss and spurious emission, allowing for improved resonance characteristics and size reduction without significant propagation loss.
Implementation Method 1
a piezoelectric layer extending in the first direction of the support
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 at least partially overlapping the interdigital transducer electrode. The piezoelectric layer has at least one 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, and overlaps an end portion of the at least one first electrode finger that is not connected to the first busbar electrode.