Composite Lamb Wave Element for High-Frequency Q Retention
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Solution Overview
Problem
Existing acoustic wave elements, such as delay lines and resonators, face challenges in achieving high frequency operation while maintaining a high quality factor (Q) and large effective electromechanical coupling coefficient (k2), especially in radio frequency electronic systems.
Innovation Solution
The acoustic wave element comprises a piezoelectric layer of aluminum nitride, a diamond-like carbon layer, and an interdigital transducer electrode. The piezoelectric layer is positioned between the interdigital transducer electrode and the diamond-like carbon layer, with a support layer, such as a silicon layer, under the diamond-like carbon layer. This configuration enhances high-frequency operation and structural ruggedness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing acoustic wave elements are used for high frequency operation, then frequency response can be achieved, but quality factor (Q) and electromechanical coupling coefficient (k2) deteriorate
Solution Approach 1:
The patent employs a composite structure consisting of a piezoelectric layer (e.g., aluminum nitride or scandium aluminum nitride) bonded to a support layer (e.g., silicon, silicon dioxide, or sapphire). This composite configuration enables high-frequency operation up to 10 GHz while maintaining high quality factor and electromechanical coupling coefficient, resolving the contradiction between frequency response and performance degradation.
2Speed
If existing acoustic wave elements are used for high frequency operation, then frequency response can be achieved, but electromechanical coupling coefficient (k2) deteriorates
Solution Approach 1:
The piezoelectric layer combined with the support layer creates a composite acoustic wave element that maintains large effective electromechanical coupling coefficient even at high frequencies up to 10 GHz, preventing the deterioration of k2 that occurs in conventional single-layer structures.
3Speed
If conventional acoustic wave elements are used, then basic acoustic wave generation is achieved, but structural ruggedness is insufficient for high-frequency operation
Solution Approach 1:
The support layer (silicon, silicon dioxide, or sapphire) provides enhanced structural ruggedness and mechanical stability to the piezoelectric layer, enabling the acoustic wave element to withstand high-frequency operation up to 10 GHz without structural degradation.
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 acoustic wave element achieves high-frequency operation up to 10 GHz with improved structural ruggedness, maintaining a high quality factor (Q) and large effective electromechanical coupling coefficient (k2), thus enabling low-loss filters and delay lines for radio frequency applications.
Implementation Method 1
A piezoelectric layer can include aluminum nitride (AlN) or scandium aluminum nitride (ScAlN). An IDT electrode can be positioned over the AlN piezoelectric layer
Data Source
AI summary
An acoustic wave element is disclosed. The acoustic wave element can include a piezoelectric layer that includes aluminum nitride. The acoustic wave element can also include a diamond like carbon layer. The acoustic wave element can further include an interdigital transducer electrode that is positioned on the piezoelectric layer. The piezoelectric layer is positioned between the interdigital transducer electrode and the diamond like carbon layer. The acoustic wave element is configured to generate a Lamb wave having a wavelength of λ.