Acoustic Wave Electrode Layout Across Mixed Crystal Orientations
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Solution Overview
Problem
Existing acoustic wave devices face challenges in readily adjusting fractional band widths due to independently formed resonators with differing c-axis directions.
Innovation Solution
Incorporating a piezoelectric substrate with regions having different crystal orientations or structures, and a functional electrode that overlaps these regions, allowing for adjustable fractional band widths through controlled film formation and surface treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If resonators are independently formed on portions with different c-axis directions, then crystal orientation control is achieved, but fractional band width adjustment becomes difficult
Solution Approach 1:
The piezoelectric layer is divided into multiple regions with different crystal orientations (first region with first c-axis direction, second region with second c-axis direction). Each region can be independently controlled to have specific crystal orientations, allowing the functional electrode to overlap with different oriented regions to achieve fractional band width adjustment while maintaining precise crystal orientation control.
Solution Approach 2:
Different portions of the piezoelectric layer are given different local crystal orientation qualities. The first region has a first c-axis direction and the second region has a second c-axis direction, creating local quality variations that enable the functional electrode to achieve both crystal orientation control and fractional band width adjustment by overlapping with specific regions.
2Adaptability or versatility
If multiple resonators are formed with different c-axis directions, then crystal structure diversity is achieved, but device complexity increases
Solution Approach 1:
Multiple resonator functions are merged into a single integrated structure. The functional electrode overlaps with both the first region and second region of the piezoelectric layer, combining the crystal structure diversity of multiple oriented regions into one device, thereby achieving adaptability without proportionally increasing device complexity.
Solution Approach 2:
The piezoelectric layer serves multiple functions simultaneously by containing both first and second regions with different crystal orientations. This multi-functional design allows a single layer to provide diverse crystal structures for different resonator operations, reducing the need for separate independent resonator structures.
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
Enables precise adjustment of fractional band widths and enhances electromechanical coupling coefficients, improving design flexibility and electrical characteristics of acoustic wave devices.
Implementation Method 1
a piezoelectric substrate including a piezoelectric layer
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer and a functional electrode on the piezoelectric layer and including electrode fingers. The piezoelectric layer includes at least a first region and a second region with crystal orientations different from each other. The functional electrode overlaps the first region and the second region in plan view.