SAW Resonator Piston Mode Layout for Higher ESD Strength
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Solution Overview
Problem
Surface acoustic wave (SAW) resonators with piston mode design have a higher sensitivity to electrostatic discharge (ESD) due to shorter distances between electrode fingers, leading to potential irreversible damage during assembly and handling, which reduces fabrication yield and increases returns due to ESD-related issues.
Innovation Solution
The design removes piston-mode hammer heads from specific electrode fingers in transition regions, increasing the distance between adjacent fingers and enhancing ESD strength, allowing the electroacoustic device to withstand higher voltages during ESD events, with a maximum increase of up to three times the withstand voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piston mode design is used with shorter distances between electrode fingers, then filtering performance is improved, but ESD strength deteriorates
Solution Approach 1:
The patent applies different finger configurations to different regions of the electrode structure. Transition region fingers have modified geometries (different widths, heights, or spacing) compared to regular fingers, creating local variations that provide ESD protection specifically where needed while preserving the piston mode performance in the main active region.
2Volume of moving object
If shorter distances between electrode fingers are used, then device size is reduced, but ESD strength deteriorates
Solution Approach 1:
The invention introduces regional variations in finger geometry only in transition areas, while maintaining compact finger spacing in the main active region. This allows the device to achieve small overall size while providing localized ESD protection where voltage stress is highest.
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 removal of hammer heads in specific regions of the electroacoustic device significantly enhances its ESD strength, reducing the risk of damage during assembly and handling, thereby improving the fabrication yield and reducing returns due to ESD-related issues.
Implementation Method 1
Using a piezoelectric material as a vibrating medium, acoustic resonators operate by transforming an electrical signal wave that is propagating along an electrical conductor into an acoustic wave that is propagating via the piezoelectric material.
Implementation Method 2
a first electrode structure disposed above the piezoelectric material, the first electrode structure comprising first electrode fingers arranged within an active region having a first region and a second region
Data Source
AI summary
Certain aspects of the present disclosure provide a surface acoustic wave (SAW) resonator with piston mode design and electrostatic discharge (ESD) protections. An example electroacoustic device generally includes a piezoelectric material and a first electrode structure disposed above the piezoelectric material. The first electrode structure comprises first electrode fingers arranged within an active region having a first region and a second region. At least one of the first electrode fingers has at least one of a different width or a different height in the first region than in the second region, and the first electrode fingers comprise a first electrode finger that has a width or height in the second region that is less than a corresponding width or height of the at least one of the first electrode fingers in the second region.