BAW Resonator Edge Structure for Blocking Transverse Leakage
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Solution Overview
Problem
Bulk acoustic wave (BAW) resonators suffer from leakage of acoustic waves at lateral edges of the resonance region in the transverse mode, leading to reduced quality factor (Q value) and increased insertion loss.
Innovation Solution
The implementation of a bulk acoustic wave resonance device with an asymmetrical edge structure that differs in acoustic impedance from the middle part of the resonance region, effectively reducing leakage waves in the transverse mode and enhancing the Q value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional BAW resonator structure is used, then the manufacturing process is simpler, but acoustic waves leak at lateral edges causing reduced Q value and increased insertion loss
Solution Approach 1:
The patent introduces an asymmetrical edge structure at the lateral edges of the resonance region, where the acoustic impedance differs from the middle part. This asymmetry creates acoustic reflection at the edges, preventing transverse mode leakage and reducing acoustic energy loss, thereby improving the Q value without significantly complicating the manufacturing process
Solution Approach 2:
The patent applies a localized modification at the lateral edges of the resonance region by introducing the asymmetrical edge structure. This local change in acoustic impedance specifically targets the leakage problem at the edges while maintaining the overall simplicity of the BAW resonator structure, reducing acoustic energy loss without requiring global structural complexity
2Reliability
If an asymmetrical edge structure is introduced to reduce leakage, then the Q value increases, but the manufacturing process becomes more complicated
Solution Approach 1:
The asymmetrical edge structure is designed to be integrated into the existing BAW resonator fabrication process. By creating a localized asymmetry at the lateral edges through standard semiconductor manufacturing techniques, the patent achieves improved Q value and reliability while minimizing the increase in manufacturing complexity
Solution Approach 2:
The patent modifies the acoustic impedance parameter at the lateral edges by introducing the asymmetrical edge structure. This parameter change is achieved through controlled material deposition or structural modification during the manufacturing process, allowing for improved Q value while keeping the manufacturing process relatively simple through precise parameter control
3Object-generated harmful factors
If the acoustic impedance at lateral edges is made different from the middle part, then leakage waves are reduced, but the device structure becomes more complex
Solution Approach 1:
The patent introduces a minimal asymmetrical feature at the lateral edges to create the necessary acoustic impedance difference. This asymmetrical edge structure is designed to be as simple as possible while still achieving the goal of reflecting transverse mode acoustic waves and reducing leakage, thereby minimizing the increase in device structural complexity
Solution Approach 2:
The patent applies a localized asymmetrical edge structure only at the lateral edges where leakage occurs, rather than modifying the entire resonator structure. This local modification creates the necessary acoustic impedance difference to reduce leakage waves while keeping the overall device structure simple and maintaining ease of fabrication
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 proposed solution effectively reduces acoustic energy loss by minimizing leakage at the lateral edges, thereby increasing the Q value and improving the overall performance of the BAW filter device.
Implementation Method 1
acoustic waves is generated by the piezoelectric layer under the alternating voltages with different polarities
Implementation Method 2
the acoustic waves within the resonator propagates in a direction perpendicular to the piezoelectric layer
Implementation Method 3
the acoustic waves require total reflection on an upper surface of an upper metal electrode and on a lower surface of a lower metal electrode to form a standing acoustic wave
Data Source
AI summary
Provided in the embodiments of the present invention are a bulk acoustic wave resonance device, a filter device, and a radio frequency front-end device. The bulk acoustic wave resonance device comprises: a first layer comprising a cavity; a first electrode layer having at least one end located in the cavity; a piezoelectric layer, which is located on the first electrode layer to cover the cavity and comprises a first side and a second side that is opposite the first side in a vertical direction, the first electrode layer being located on the first side; a second electrode layer located on the second side and on the piezoelectric layer; and at least one edge structure, which is located at an edge of an overlapping portion of the first electrode layer and the second electrode layer in a horizontal direction and is of an asymmetric structure in the vertical direction with respect to the piezoelectric layer. The acoustic impedance of an edge portion where the at least one edge structure is located does not match the acoustic impedance of a middle portion between the at least one edge structure, that is, the acoustic impedances are different, such that leaky waves can be blocked in a transverse mode and a Q value can be increased.