FBAR Raised Frame Openings for Lower Parasitic Resonance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The intensity of parasitic resonance peaks introduced by the raised frame in film bulk acoustic resonators is excessively high, leading to performance degradation without a corresponding reduction in the Q value.
Innovation Solution
A film bulk acoustic resonator design featuring a raised frame with strategically placed openings in the resonance region, which reduces the area ratio of the raised frame and minimizes the intensity of parasitic resonance peaks without affecting the Q value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of the raised frame increases to reduce energy leakage and improve Q value, then the Q value increases, but the area ratio of the raised frame continuously increases resulting in enhanced parasitic resonance peak intensity
Solution Approach 1:
The raised frame is designed with openings (through holes or blind holes) forming a porous structure. This porous configuration reduces the effective area ratio of the raised frame in the resonance region, thereby suppressing parasitic resonance peaks while maintaining the acoustic impedance mismatch function for reflecting transverse parasitic acoustic waves and preserving the Q value.
Solution Approach 2:
The raised frame is segmented by introducing multiple openings that divide the continuous frame structure into separate regions. This segmentation reduces the overall area ratio of the raised frame while maintaining its functional integrity for acoustic wave reflection and parasitic wave suppression.
2Object-generated harmful factors
If the area ratio of the raised frame is reduced to minimize parasitic resonance peaks, then parasitic resonance peak intensity decreases, but the acoustic impedance mismatch and energy reflection capability may be compromised
Solution Approach 1:
The porous structure with openings maintains the raised frame's acoustic impedance mismatch function by preserving the structural framework and height difference, while the openings reduce the effective area ratio to suppress parasitic resonance peaks without significantly compromising the Q value.
Solution Approach 2:
The raised frame with openings creates local variations in acoustic impedance distribution. The openings are strategically positioned to maintain high acoustic impedance at critical reflection points while reducing overall area ratio, achieving localized optimization of both parasitic suppression and Q value maintenance.
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 design effectively reduces the area ratio of the raised frame in the resonance region, thereby minimizing parasitic resonance peaks and enhancing the performance of the resonator without increasing manufacturing complexity.
Implementation Method 1
when radio frequency electrical signals are applied to the top electrode and the bottom electrode, a piezoelectric film undergoes mechanical vibration in a longitudinal direction due to the inverse piezoelectric effect, to form bulk acoustic waves
Implementation Method 2
The bulk acoustic waves are converted into electrical signals due to the piezoelectric effect
Implementation Method 3
The RAF increases the acoustic impedance mismatch between the central region and the outside of the resonance region such that transverse parasitic acoustic waves, mainly Rayleigh Lamb waves, propagating toward the outside of the resonance region are reflected back to the resonance region
Data Source
AI summary
A film bulk acoustic resonator, including: a substrate; an acoustic reflection structure; a bottom electrode; a piezoelectric film; a top electrode; and a raised frame. A spatial region formed by overlapping of the acoustic reflection structure, the bottom electrode, and the piezoelectric film and the top electrode in a thickness direction of the film bulk acoustic resonator is a resonance region, in which the raised frame is arranged, and openings are formed at a side of the raised frame away from the top electrode. The film bulk acoustic resonator can reduce the area ratio of the raised frame in the resonance region and the intensity of the parasitic resonance peak introduced by the raised frame without reducing the Q value of the resonator and without increasing manufacturing process steps.