Multi-Layer IDT Electrode Structure for Low-Loss SAW Filters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Acoustic wave filters, particularly surface acoustic wave (SAW) filters, face challenges in achieving low insertion loss, which is essential for radio frequency electronic systems, due to limitations in conductor loss and electrical characteristics.
Innovation Solution
The implementation of a multi-layered interdigital transducer (IDT) electrode structure with a thicker aluminum layer over a molybdenum layer, combined with a silicon dioxide temperature compensation layer, reduces insertion loss while maintaining electrical properties and acoustic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional single-layer IDT electrode is used, then the device structure is simple, but the insertion loss is high due to conductor loss
Solution Approach 1:
The IDT electrode is segmented into multiple layers (first IDT electrode layer and second IDT electrode layer) with different materials and functions. The first layer provides acoustic coupling to the piezoelectric substrate, while the second layer provides low-resistance electrical conduction, thereby reducing overall conductor loss and insertion loss without requiring a single complex thick layer
Solution Approach 2:
The patent uses composite material structure by combining different materials in the IDT electrode layers. The first layer uses materials with good acoustic impedance matching to the piezoelectric substrate, while the second layer uses materials with high electrical conductivity. This composite approach optimizes both acoustic performance and electrical performance, reducing insertion loss effectively
2Loss of energy
If the IDT electrode layer thickness is increased to reduce conductor loss, then insertion loss decreases, but the acoustic performance and electrical characteristics may deteriorate
Solution Approach 1:
By dividing the electrode into multiple layers with optimized individual thicknesses, each layer can be independently optimized for its specific function. The first layer thickness is optimized for acoustic coupling, while the second layer thickness is optimized for electrical conduction. This prevents the acoustic performance deterioration that would occur with a single thick layer while still achieving low insertion loss through reduced conductor loss
Solution Approach 2:
The patent optimizes specific parameter ranges for each layer thickness. The first IDT electrode layer has a thickness optimized for acoustic coupling, and the second IDT electrode layer has a thickness optimized for electrical conduction. By independently controlling these parameters, the patent achieves low insertion loss while maintaining stable acoustic and electrical performance
3Loss of energy
If a thicker second IDT electrode layer is used to reduce insertion loss, then conductor loss decreases, but the temperature compensation effect may be affected
Solution Approach 1:
The segmentation of the IDT electrode into multiple layers allows the temperature compensation layer to be positioned specifically over the first IDT electrode layer, which is in direct contact with the piezoelectric substrate. This positioning ensures that the temperature compensation effect remains stable and effective, while the second layer provides the necessary low-resistance conduction path to reduce insertion loss without interfering with the temperature compensation mechanism
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 effectively reduces insertion loss in SAW devices, improving their performance by optimizing the thickness of the IDT electrode layers and temperature compensation, thereby enhancing the acoustic wave device's efficiency in filtering radio frequency signals.
Implementation Method 1
A surface acoustic wave resonator of a surface acoustic wave filter typically includes an interdigital transductor electrode on a piezoelectric substrate
Implementation Method 2
A surface acoustic wave resonator is arranged to generate a surface acoustic wave
Data Source
AI summary
Aspects of this disclosure relate to an acoustic wave device that includes a multi-layer interdigital transducer electrode. The acoustic wave device includes a piezoelectric layer and an interdigital transducer electrode on the piezoelectric layer. The interdigital transducer electrode includes a first interdigital transducer electrode layer positioned between a second interdigital transducer electrode layer and the piezoelectric layer. The second interdigital transducer electrode layer can include aluminum and having a thickness of at least 200 nanometers. The acoustic wave device can include a temperature compensation layer arranged such that the interdigital transducer electrode is positioned between the piezoelectric layer and at least a portion of the temperature compensation layer. Related filters, modules, wireless communication devices, and methods are disclosed.