Lateral Shear Mode Acoustic Resonator Mirror for 3 GHz+ Q and Coupling
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Solution Overview
Problem
Existing radio frequency acoustic resonators face challenges in maintaining high electromechanical coupling coefficients and Q values above 3 GHz, which are necessary for new communication standards like 5G.
Innovation Solution
A method for fabricating a laterally excited shear mode acoustic resonator using a piezoelectric layer of monocrystalline lithium niobate or lithium tantalate, combined with an acoustic mirror and electrode unit, to generate an electric field and laterally reflect sound waves, achieving high electromechanical coupling and Q values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional acoustic resonator designs are used, then manufacturing simplicity is maintained, but electromechanical coupling coefficient and Q value deteriorate at frequencies above 3 GHz
Solution Approach 1:
The acoustic mirror is segmented into multiple alternating layers of first and second acoustic reflection layers with different acoustic impedances. This segmentation creates a distributed acoustic reflection structure that effectively reflects acoustic waves while maintaining a manageable layer thickness, thereby achieving high electromechanical coupling coefficient without excessive device complexity.
Solution Approach 2:
The acoustic mirror employs composite material structure with alternating layers of materials having different acoustic impedances. This composite approach enables effective acoustic wave reflection through impedance mismatch between layers, improving the electromechanical coupling coefficient while keeping the overall mirror thickness within acceptable limits.
2Reliability
If conventional acoustic resonator designs are used, then structural simplicity is maintained, but Q value deteriorates at frequencies above 3 GHz
Solution Approach 1:
The acoustic mirror is divided into multiple alternating reflection layers that segment the acoustic wave reflection function across multiple interfaces. This segmentation reduces energy loss at each individual interface while collectively achieving high Q value through cumulative reflection effect, without requiring excessive overall structure complexity.
Solution Approach 2:
The composite material structure of alternating acoustic reflection layers with different impedances creates multiple reflection interfaces that collectively minimize energy dissipation. This composite approach maintains high Q value by reducing acoustic energy loss through the mirror while keeping the structure practically implementable.
3Speed
If operating frequency is increased above 3 GHz for 5G standards, then communication performance is improved, but maintaining high electromechanical coupling coefficient becomes difficult
Solution Approach 1:
The invention changes the acoustic impedance parameters of the reflection layers by selecting materials and thicknesses that optimize acoustic reflection at higher frequencies. By adjusting these parameters, the acoustic mirror effectively reflects acoustic waves at frequencies above 3 GHz, enabling maintenance of high electromechanical coupling coefficient at 5G operating frequencies.
Solution Approach 2:
The composite material structure with alternating layers provides frequency-tunable acoustic reflection characteristics. By selecting appropriate materials and layer thicknesses, the structure is optimized for higher frequency operation, enabling 5G communication performance while maintaining strong electromechanical coupling.
4Speed
If operating frequency is increased above 3 GHz for 5G standards, then communication capability is improved, but maintaining high Q value becomes difficult
Solution Approach 1:
The acoustic impedance parameters and layer thicknesses are specifically optimized for higher frequency operation. This parameter optimization ensures that acoustic energy is effectively reflected with minimal loss at frequencies above 3 GHz, thereby maintaining high Q value at 5G operating frequencies.
Solution Approach 2:
The composite material structure provides frequency-selective acoustic reflection that is optimized for 5G bands. The alternating layers create constructive interference for reflected waves at target frequencies while minimizing energy loss, enabling high Q value maintenance at elevated operating frequencies.
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 resonator supports high-performance passband filters and meets the requirements of 5G communication standards by operating at frequencies above 3 GHz with improved acoustic properties.
Implementation Method 1
providing a piezoelectric layer including monocrystalline lithium niobate and/or monocrystalline lithium tantalate
Implementation Method 2
forming an acoustic mirror on the first surface; the acoustic mirror including at least one first acoustic reflection layer and at least one second acoustic reflection layer
Implementation Method 3
the lateral reflector being used for laterally reflecting a sound wave
Implementation Method 4
Method for manufacturing acoustic resonator in lateral excitation shear mode
Data Source
AI summary
The present disclosure relates to a method for fabricating a laterally excited shear mode acoustic resonator. The method includes: providing a piezoelectric layer including monocrystalline lithium niobate and/or monocrystalline lithium tantalate; forming an acoustic mirror on a first surface of the piezoelectric layer; the acoustic mirror including at least one first acoustic reflection layer and at least one second acoustic reflection layer, the first acoustic reflection layers and the second acoustic reflection layers being alternately superimposed, and acoustic impedance of each of the first acoustic reflection layers being less than that of each of the second acoustic reflection layers; bonding a bearing wafer on a first surface of the acoustic mirror; and forming an electrode unit and a lateral reflector on a second surface of the piezoelectric layer.