Tapered Mass Loading Strip for TCSAW Transverse Mode Suppression
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Solution Overview
Problem
Piezoelectric MEMS resonators, particularly TCSAW resonators, face challenges in suppressing transverse modes, which affect the accuracy and stability of oscillators and sensors, and degrade the performance of acoustic wave filters by creating passband ripples and limiting rejection.
Innovation Solution
Incorporating a mass loading strip with a tapered sidewall into the acoustic wave device, where the top side is shorter than the bottom side, and the sidewall is angled inwardly between 10 to 90 degrees, to mitigate void formation in the temperature compensation layer and enhance transverse mode suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mass loading strip is used for transverse mode suppression, then the suppression effectiveness is improved, but void formation occurs in the temperature compensation layer
Solution Approach 1:
The mass loading strip employs asymmetric geometry with a tapered sidewall where the top width is smaller than the bottom width. This asymmetric design allows the strip to effectively suppress transverse modes while reducing the lateral pressure on the temperature compensation layer, thereby preventing void formation. The tapered configuration creates a gradual transition that maintains layer integrity.
Solution Approach 2:
The invention changes the geometric parameters of the mass loading strip by introducing a taper angle (10-90 degrees) and varying the width from bottom to top. This parameter modification optimizes the balance between suppression effectiveness and void prevention, allowing the strip to maintain strong coupling for mode suppression while minimizing stress concentration that would cause delamination.
2Ease of manufacture
If the mass loading strip has a vertical sidewall, then the manufacturing is simpler, but void formation occurs in the temperature compensation layer
Solution Approach 1:
Rather than using a simple vertical sidewall, the invention introduces a controlled asymmetry through the tapered sidewall design. This moderate complexity increase in fabrication is justified by the significant improvement in preventing void formation and delamination, while still maintaining compatibility with standard semiconductor manufacturing processes.
3Stability of the object's composition
If the top side of the mass loading strip is made shorter than the bottom side, then void formation is mitigated, but the device complexity increases
Solution Approach 1:
The invention modifies a single geometric parameter - the sidewall angle - to create the tapered profile. This straightforward parameter change achieves the dual benefit of preventing void formation and maintaining manufacturing feasibility, without requiring complex multi-step fabrication processes or additional structural elements.
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 tapered sidewall design effectively suppresses transverse modes, maintaining the acoustic properties and improving the performance of acoustic wave filters by reducing passband ripples and enhancing rejection.
Implementation Method 1
a mass loading strip with a tapered sidewall into the acoustic wave device, where the top side is shorter than the bottom side, and the sidewall is angled inwardly between 10 to 90 degrees, to mitigate void formation in the temperature compensation layer and enhance transverse mode suppression
Implementation Method 2
Piezoelectric MEMS resonators can process electrical signals using mechanically vibrating structures
Implementation Method 3
a temperature compensation layer over the interdigital transducer electrode
Data Source
AI summary
Aspects of this disclosure relate to an acoustic wave device with transverse mode suppression. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a mass loading strip. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. The mass loading strip can have a sidewall that is tapered inwardly from a bottom side of the mass loading strip to a top side of the mass loading strip. The top side can be shorter than the bottom side.