BAW Electrode Protrusion Layout for Spurious Mode Suppression
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Solution Overview
Problem
Bulk acoustic wave (BAW) devices often suffer from spurious modes that lead to undesirable energy leakage and performance degradation.
Innovation Solution
The acoustic wave device incorporates a piezoelectric layer sandwiched between two electrodes, where the second electrode features a plurality of protrusions with gaps that expose the piezoelectric layer, creating a slow zone to confine acoustic wave energy and suppress spurious modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional BAW device structure is used, then the device can convert and transceive electrical and acoustic signals, but spurious modes occur causing energy leakage and performance degradation
Solution Approach 1:
The second electrode is segmented into multiple protrusions with gaps between them, creating a structured pattern that segments the acoustic wave path. This segmentation prevents spurious modes by creating distinct acoustic paths while maintaining electrical functionality, thereby reducing energy leakage and improving performance stability
Solution Approach 2:
The electrode structure transitions from a uniform conventional design to a non-uniform design with protrusions and gaps. This local quality change creates specific regions (gaps) that expose the piezoelectric layer and control acoustic wave propagation locally, suppressing spurious modes in critical areas while maintaining overall device functionality
2Reliability
If the second electrode is designed with protrusions and gaps, then spurious modes are suppressed and quality factor is enhanced, but device structure becomes more complex
Solution Approach 1:
The second electrode is divided into multiple protrusions with gaps, creating a segmented structure that suppresses spurious modes. While this increases structural complexity, the segmentation is achieved through standard photolithography patterning processes, making the complexity manageable and manufacturable
Solution Approach 2:
The electrode geometry parameters (protrusion height, gap width, protrusion spacing) are optimized to achieve spurious mode suppression. By carefully controlling these parameters within specific ranges, the device achieves enhanced quality factor while maintaining compatibility with standard manufacturing processes
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 quality factor of the acoustic wave device by reducing energy leakage and suppressing spurious modes, leading to improved performance and efficiency.
Implementation Method 1
The piezoelectric layer is disposed at least partially on the first electrode. The second electrode is disposed at least partially on the piezoelectric layer.
Data Source
AI summary
An acoustic wave device includes a first electrode, a piezoelectric layer and a second electrode. The piezoelectric layer is disposed at least partially on the first electrode. The second electrode is disposed at least partially on the piezoelectric layer. The second electrode includes an electrode body having an outline and a plurality of protrusions extending from the outline of the electrode body. The two ends of two adjacent ones of the plurality of protrusions are separated by a gap and the gap exposes at least a portion of the piezoelectric layer.