Acoustic Resonator Dielectric Finger Layout for k2eff Stability
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Solution Overview
Problem
Bulk acoustic wave (BAW) resonators face challenges in achieving consistent effective coupling coefficient (k2eff) across designed frequency ranges due to film-stack dependent resonant frequency, increasing fabrication complexity and cost, and existing micro-acoustic resonator designs struggle to match the coupling coefficient of BAW resonators.
Innovation Solution
The design incorporates a piezoelectric layer with a first electrode and a plurality of dielectric structures on one surface, and a second electrode on the opposing surface, where the dielectric structures are in contact with neighboring electrode structures, allowing for adjustable resonant frequency through lithographic patterning and enhancing the effective coupling coefficient by using dielectric materials like aluminum oxide (Al2O3) to fill spaces between electrode fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BAW resonators use film-stack dependent resonant frequency design, then resonant frequency can be controlled, but fabrication complexity and cost increase due to trimming or adding loading layers
Solution Approach 1:
The patent changes the control parameter from film-stack modification to electrode patterning. By varying electrode geometry parameters (width, spacing, arrangement) in the lateral direction, the resonant frequency is adjusted without modifying the vertical film stack, thereby simplifying fabrication processes and reducing costs.
Solution Approach 2:
The patent transitions from controlling resonant frequency in the vertical dimension (film-stack thickness) to the lateral dimension (electrode patterning). This dimensional shift allows frequency tuning through planar electrode design rather than complex vertical film deposition and trimming operations.
2Device complexity
If emerging micro-acoustic resonators use electrode patterning to adjust operating frequency, then fabrication complexity is reduced, but effective coupling coefficient (k2eff) decreases compared to BAW resonators
Solution Approach 1:
The patent employs composite electrode structures combining different materials or multi-layer electrode configurations. This composite approach enhances the effective coupling coefficient by optimizing the interaction between electrodes and the acoustic wave, while maintaining the simplified electrode patterning fabrication process.
Solution Approach 2:
The patent applies local quality optimization by varying electrode properties (material composition, thickness, geometry) in specific regions of the resonator. This localized optimization enhances the coupling coefficient in critical areas while maintaining overall fabrication simplicity through standard lithographic patterning techniques.
3Measurement precision
If BAW resonators add loading layers to achieve different frequencies, then resonant frequency is adjusted, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the adjustment parameter from film-stack thickness (requiring high precision deposition and trimming) to electrode lateral dimensions (controlled by standard lithography). This parameter substitution reduces manufacturing precision requirements while maintaining accurate resonant frequency control.
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 improves the effective coupling coefficient (k2eff) of the resonators, enabling better bandwidth performance and reducing fabrication complexity by maintaining consistent coupling across the desired frequency range.
Implementation Method 1
a piezoelectric layer
Implementation Method 2
a plurality of dielectric structures in contact with the first surface of the piezoelectric layer
Implementation Method 3
acoustic resonator
Data Source
AI summary
Various embodiments may relate to an acoustic resonator. The acoustic resonator may include a piezoelectric layer. The acoustic resonator may also include a first electrode in contact with a first surface of the piezoelectric layer. The acoustic resonator may further include a plurality of dielectric structures in contact with the first surface of the piezoelectric layer. The acoustic resonator may additionally include a second electrode in contact with a second surface of the piezoelectric layer opposite the first surface. The first electrode may include a plurality of electrode structures. A dielectric structure of the plurality of dielectric structures may be in contact with a pair of neighboring electrode structures of the plurality of electrode structures.