MPS SAW Temperature Compensation Using Germanium Oxide Layers
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Solution Overview
Problem
Existing surface acoustic wave devices suffer from performance degradation due to high temperature coefficient of frequency (TCF) and increased size, particularly in multilayer piezoelectric substrate (MPS) SAW devices, which use silicon dioxide as a temperature compensation layer.
Innovation Solution
Incorporating a germanium oxide layer with lower acoustic velocity and higher permittivity than silicon dioxide as a temperature compensation structure in the MPS SAW devices, optionally combined with a silicon oxide layer, to reduce device size and improve temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silicon dioxide is used as a temperature compensation layer in MPS SAW devices, then temperature compensation is provided, but the device size increases and TCF is high
Solution Approach 1:
The patent changes the material parameter of the temperature compensation layer from silicon dioxide to germanium oxide, which has different physical properties (lower acoustic velocity, higher permittivity). This parameter change enables the same temperature compensation function with reduced device size and improved TCF characteristics
Solution Approach 2:
The patent employs a composite structure with multiple layers including germanium oxide layer, silicon oxide layer, and piezoelectric layer. This composite material approach allows optimization of both temperature compensation and device size by combining materials with complementary properties
2Volume of moving object
If germanium oxide layer is used as temperature compensation structure, then device size is reduced and TCF is improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies optimized thickness ranges for the germanium oxide layer (300-800 nm) and silicon oxide layer (200-500 nm) to achieve the desired balance between device size reduction and manufacturability. These parameter optimizations make the complex structure practically manufacturable
3Temperature
If temperature compensation structure is added to MPS SAW devices, then TCF is improved, but device complexity increases
Solution Approach 1:
The patent divides the temperature compensation function into multiple segmented layers (germanium oxide layer and silicon oxide layer) with distinct thicknesses and properties. This segmentation allows independent optimization of each layer's contribution to TCF while managing overall device 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
The germanium oxide layer reduces acoustic velocity, increases static capacitance, and provides more positive TCF, enabling size reduction and improved performance compared to silicon dioxide, while maintaining a high coupling coefficient.
Implementation Method 1
Incorporating a germanium oxide layer with lower acoustic velocity and higher permittivity than silicon dioxide
Implementation Method 2
Incorporating a germanium oxide layer with lower acoustic velocity and higher permittivity than silicon dioxide
Implementation Method 3
Each resonator can include a surface acoustic wave device. Example piezoelectric MEMS resonators include surface acoustic (SAW) resonators
Data Source
AI summary
A surface acoustic wave device is disclosed. The surface acoustic wave device can include a support substrate, a piezoelectric layer over the support substrate, a temperature compensation structure between the support substrate and the piezoelectric layer, an interdigital transducer electrode in electrical communication with the piezoelectric layer. The temperature compensation structure includes a material having a lower acoustic velocity and higher permittivity than silicon oxide.