BAW Resonator Optimized Outer Perimeter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bulk acoustic wave (BAW) resonators suffer from spurious lateral mode propagation due to freely oscillating piezoelectric material outside the active region, leading to energy loss and reduced resonator quality, which is partially mitigated by frame structures that can compromise electromagnetic coupling.
Innovation Solution
The optimization of the outer perimeter of BAW resonators using microelectromechanical system (MEMS) fabrication techniques, where a quadratic surface scaffold is used to conformally deposit inner and outer electrodes and a piezoelectric material, reducing spurious mode excitation and energy loss while maintaining electromagnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a frame structure is added near the outer perimeter to suppress lateral modes, then spurious mode propagation is reduced, but electromagnetic coupling and resonator quality are reduced
Solution Approach 1:
The patent extracts and removes the harmful peripheral piezoelectric material that causes spurious lateral mode propagation. By eliminating this material through precision patterning techniques, the source of the harmful oscillations is removed without introducing a frame structure that would compromise electromagnetic coupling and resonator quality.
Solution Approach 2:
The patent applies different material properties to different regions of the resonator. The active region maintains full piezoelectric material for optimal performance, while the peripheral region has the piezoelectric material removed or modified to prevent spurious modes. This local differentiation allows suppression of harmful modes without affecting the quality of the active region.
2Loss of energy
If the outer perimeter is reduced to suppress spurious modes, then energy loss is reduced and quality is improved, but the active region size is reduced
Solution Approach 1:
The patent changes the geometric parameters of the resonator by implementing non-standard outer perimeters such as rounded corners, chamfered edges, or inverted chamfers. These parameter modifications reduce the peripheral piezoelectric material that causes spurious modes while maintaining the active region area through optimized design of the perimeter geometry.
3Ease of manufacture
If conventional fabrication techniques are used, then manufacturing is simpler, but the outer perimeter cannot be precisely optimized to suppress spurious modes
Solution Approach 1:
The patent employs curvature in the outer perimeter design, such as rounded corners or curved edges, which can be effectively manufactured using precision patterning techniques. These curved geometries reduce spurious mode propagation by eliminating sharp corners that act as mode generators, while the precision patterning processes enable accurate realization of these curved features.
Solution Approach 2:
The patent transitions from two-dimensional planar patterns to three-dimensional perimeter structures by incorporating vertical features such as chamfers or inverted chamfers on the resonator edges. These dimensional additions provide additional mechanisms for suppressing spurious modes while maintaining compatibility with standard semiconductor fabrication 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 approach effectively suppresses spurious lateral modes, enhancing the quality of the resonator by reducing energy loss and maintaining electromagnetic coupling, thus improving the filtering performance of BAW resonators.
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 signal wave that is propagating via the piezoelectric material.
Data Source
AI summary
Example implementations of a bulk acoustic wave resonator with an optimized outer perimeter are disclosed. In an example aspect, a resonator includes a truncated-ellipsoid-shaped active region. The active region includes an outer electrode disposed as a first layer of the active region. The active layer also includes a piezoelectric layer disposed as a second layer of the active region with the piezoelectric layer disposed interior to the outer electrode. The active layer further includes an inner electrode disposed as a third layer of the active region with the inner electrode disposed interior to the piezoelectric layer.