Composite SAW Resonator Structure for 5G Frequency Scaling
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Solution Overview
Problem
Traditional surface acoustic wave resonators operate at frequencies lower than 3 GHz, which is insufficient for 5G communication requirements.
Innovation Solution
A high-frequency surface acoustic wave resonator is designed with a high wave velocity supporting substrate and a piezoelectric film, where the velocity of the body wave in the substrate is greater than the target elastic wave in the piezoelectric film, using materials like silicon carbide or diamond for the substrate and lithium niobate for the film, and incorporating a top electrode and cladding layer to enhance wave velocity and electromechanical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional surface acoustic wave resonator structures are used, then the device is simple to manufacture, but the operating frequency is limited to below 3 GHz
Solution Approach 1:
The patent employs a composite structure consisting of a piezoelectric film layer (e.g., lithium niobate, aluminum nitride) deposited on a high wave velocity supporting substrate (e.g., silicon carbide, diamond, sapphire). This composite configuration enables the resonator to operate at frequencies above 3 GHz by leveraging the high acoustic wave velocity in the substrate while maintaining the piezoelectric coupling necessary for resonance. The composite material approach resolves the frequency limitation without requiring complete structural redesign.
Solution Approach 2:
The patent systematically optimizes multiple parameters including piezoelectric film thickness (50-500 nm), substrate material selection (silicon carbide, diamond, sapphire), and electrode configuration to achieve high-frequency operation. By changing the acoustic wave velocity parameter through substrate material selection and optimizing the piezoelectric coupling coefficient, the resonator achieves operating frequencies above 3 GHz while maintaining manufacturability through controlled deposition processes.
2Reliability
If the piezoelectric film thickness is increased to improve coupling, then the electromechanical coupling coefficient increases, but the wave velocity in the film increases which may exceed the substrate wave velocity
Solution Approach 1:
The patent optimizes the piezoelectric film thickness parameter within a specific range (50-500 nm) to achieve the desired electromechanical coupling coefficient while controlling the wave velocity. By precisely controlling the film thickness during deposition, the design ensures that the wave velocity in the piezoelectric film remains below the substrate wave velocity, preventing energy leakage and maintaining high Q-factor operation. This parameter optimization resolves the trade-off between coupling strength and velocity control.
3Speed
If a high wave velocity substrate is used to increase operating frequency, then the resonant frequency increases, but the temperature drift stability may be affected
Solution Approach 1:
The patent selects substrate materials (silicon carbide, diamond, sapphire) that inherently possess both high acoustic wave velocity for high-frequency operation and low thermal expansion coefficients for temperature stability. The composite structure of piezoelectric film on these stable substrates maintains temperature drift stability while enabling resonant frequencies above 3 GHz. The substrate material choice simultaneously addresses both frequency and stability requirements.
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 increases the resonant frequency of the surface acoustic wave resonator while maintaining a high Q value, improves temperature drift stability, and enhances power bearing capacity by increasing the wave velocity and electromechanical coupling coefficient.
Implementation Method 1
a piezoelectric film disposed on a top surface of the high wave velocity supporting substrate
Implementation Method 2
a velocity of a body wave propagating in the high wave velocity supporting substrate is greater than a velocity of a target elastic wave propagating in the piezoelectric film
Implementation Method 3
improving the operating frequency of the surface acoustic wave resonators
Data Source
AI summary
The present disclosure provides a high frequency surface acoustic wave resonator and a method for making the same. The high frequency surface acoustic wave resonator includes: a high wave velocity supporting substrate, a piezoelectric film disposed on a top surface of the high wave velocity supporting substrate, and a top electrode disposed on a top surface of the piezoelectric film; a velocity of a body wave propagating in the high wave velocity supporting substrate is greater than a velocity of a target elastic wave propagating in the piezoelectric film. The conductivity of the high wave velocity supporting substrate is greater than 1E3 Ω·cm. The high frequency surface acoustic wave resonator and the method for making the same of the present disclosure solve the problem that the operating frequency of the traditional surface acoustic wave resonator is low.