Implanted Piezoelectric Acoustic Structure for High-Frequency Low-Loss Waves
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Solution Overview
Problem
Current acoustic devices using piezoelectric materials face limitations in high-frequency applications due to low surface wave propagation speeds and increased acoustic losses when using deposited layers, and thinning techniques for bulk waves are challenging, especially for materials like LiTaO3 and LiNbO3, which restrict the synthesis of wide-band filters and resonators with high electromechanical coupling coefficients.
Innovation Solution
Modifying the mechanical properties of piezoelectric materials by implanting species or causing diffusion to create zones with altered Young's modulus and density, allowing for the formation of acoustic structures with optimized acoustic properties, such as Bragg mirrors and phononic crystals, without the need for multiple layers or precise thickness control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface waves are used in piezoelectric substrates, then excellent reproducibility and minimized acoustic losses are achieved, but propagation speed remains relatively low (4000-5000 m/s)
Solution Approach 1:
The patent modifies the mechanical parameters (Young's modulus and density) of the piezoelectric substrate by implanting atomic species or causing diffusion, thereby changing the acoustic wave propagation speed while maintaining the single-crystal structure and low loss characteristics
Solution Approach 2:
The patent creates localized zones within the substrate with modified mechanical properties through selective implantation or diffusion, allowing different regions to have optimized properties for specific acoustic modes or frequency ranges
2Speed
If waves guided in deposited layers are used, then propagation speed increases to tens of kilometers per second, but acoustic losses increase and transduction efficiency decreases
Solution Approach 1:
The patent modifies the mechanical parameters of the piezoelectric substrate to achieve high propagation speeds comparable to deposited layer waves, while avoiding the acoustic losses by maintaining the single-crystal structure
Solution Approach 2:
The patent creates a composite structure within the single-crystal substrate by introducing implanted or diffused species, combining the advantages of high propagation speed with the low loss characteristics of single-crystal materials
3Measurement precision
If body waves are used with thinned substrates, then high frequency response is achieved, but manufacturing complexity increases due to etching challenges
Solution Approach 1:
The patent modifies the mechanical parameters of the bulk substrate through implantation or diffusion, enabling high-frequency body wave operation without requiring substrate thinning, thus avoiding etching challenges
Solution Approach 2:
The patent extracts the need for substrate thinning by modifying the mechanical properties of the bulk material, allowing high-frequency operation while maintaining the full substrate thickness and avoiding complex etching processes
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 approach enables the creation of acoustic components with improved frequency response and bandwidth, higher electromechanical coupling coefficients, and reduced acoustic losses, facilitating the design of broadband filters and resonators with enhanced performance.
Implementation Method 1
Modifying the mechanical properties of piezoelectric materials by implanting species or causing diffusion to create zones with altered Young's modulus and density
Implementation Method 2
Modifying the mechanical properties of piezoelectric materials by implanting species or causing diffusion to create zones with altered Young's modulus and density
Implementation Method 3
Single-crystal piezoelectric materials are widely used in industry, particularly for the fabrication of surface acoustic wave (SAW) components
Data Source
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AI summary
The invention relates to an acoustic structure comprising a layer of material having a first Young's modulus, called intrinsic modulus, and a first density, called intrinsic density, characterized in that the layer comprises at least a first zone (Z1) having said first Young's modulus and said first density and at least a second zone (Z2) buried in the volume of said layer of material and having a second Young's modulus and/or a second density, obtained by implantation and/or diffusion of atoms into the volume of said layer.