Multi-Layer SAW Substrate for Heat Dissipation and Spurious Mode Control
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Solution Overview
Problem
Surface acoustic wave (SAW) resonators with multi-layer piezoelectric substrates face challenges in achieving high ruggedness and power handling while maintaining low thermal heat dissipation and minimizing high frequency spurious responses.
Innovation Solution
The SAW resonators incorporate a single crystal support layer, a z-propagation quartz layer, and a lithium-based piezoelectric layer, along with an interdigital transducer electrode, where the support layer has higher thermal conductivity than the quartz and piezoelectric layers, and the quartz layer is oriented to confine acoustic energy and reduce spurious responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer piezoelectric substrate is used to achieve high quality factor, then the quality factor is improved, but thermal dissipation performance deteriorates
Solution Approach 1:
The device is divided into distinct functional layers: a first piezoelectric layer for generating surface acoustic waves and a second piezoelectric layer for thermal management. This segmentation allows each layer to specialize in its primary function, with the second layer providing thermal dissipation pathways without interfering with the wave generation in the first layer.
Solution Approach 2:
An intermediate layer is introduced between the first and second piezoelectric layers to facilitate thermal transfer while maintaining the functional integrity of both piezoelectric layers. This intermediary structure enables effective thermal management without compromising the electromechanical coupling and quality factor of the device.
2Reliability
If the piezoelectric layer thickness is increased to improve power handling, then power durability is improved, but thermal heat dissipation deteriorates
Solution Approach 1:
The piezoelectric functionality is segmented across two separate layers, allowing the first layer to be optimized for electromechanical coupling and power handling, while the second layer is optimized for thermal conduction. This eliminates the trade-off by distributing functions across dedicated structural elements.
Solution Approach 2:
The device employs a composite structure with two different piezoelectric materials or configurations, where the first material prioritizes electromechanical properties and the second material prioritizes thermal properties. This composite approach allows simultaneous optimization of both power handling and thermal dissipation.
3Ease of manufacture
If conventional manufacturing processes are used for multi-layer piezoelectric substrates, then manufacturing simplicity is maintained, but manufacturing precision deteriorates
Solution Approach 1:
The first piezoelectric layer is fully formed and stabilized before the second piezoelectric layer is introduced. This preliminary action establishes a stable foundation with precise acoustic wave pathways, allowing the subsequent layer to be added without disrupting the already-optimized first layer structure.
Solution Approach 2:
The manufacturing process is segmented into distinct stages: first forming the piezoelectric layer for wave generation, then adding the thermal management layer. This staged approach allows each manufacturing step to be optimized independently, maintaining precision while managing process complexity.
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 enhances the effective electromechanical coupling coefficient, quality factor, and power durability, leading to reduced insertion loss and compatibility with higher frequency bands, while also improving thermal dissipation and reducing high frequency spurious modes.
Implementation Method 1
the support layer has higher thermal conductivity than the quartz and piezoelectric layers
Implementation Method 2
the quartz layer is oriented to confine acoustic energy and reduce spurious responses
Implementation Method 3
The surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed.
Data Source
AI summary
A surface acoustic wave device is disclosed. The surface acoustic wave device can include a single crystal support layer, an intermediate single crystal layer positioned over the single crystal support layer, a lithium based piezoelectric layer positioned over the intermediate single crystal layer, and an interdigital transducer electrode positioned over the lithium based piezoelectric layer, the surface acoustic wave device configured to generate a surface acoustic wave. The single crystal layer can be a quartz layer, such as a z-propagation quartz layer. A thermal conductivity of the single crystal support layer is greater than a thermal conductivity of the intermediate single crystal layer, and the thermal conductivity of the single crystal support layer is greater than a thermal conductivity of the lithium based piezoelectric layer.