Oxidized IDT Electrodes for SAW Resonant Frequency Control
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Solution Overview
Problem
Surface acoustic wave devices face challenges in precisely controlling their frequency distribution due to the complexity of individually managing the thickness of IDT electrodes, piezoelectric layers, and energy confining layers, especially with the increasing demands of advanced communication technologies like 5G carrier aggregation.
Innovation Solution
The introduction of an oxide electrode layer formed by oxidation on IDT electrodes, which allows for precise control of the thickness and density of the oxide layer, enabling adjustment of the resonant frequency by varying the oxidation process parameters such as ion beam scan rate and dwell time, thereby optimizing frequency distribution, peak loss, and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of IDT electrodes, piezoelectric layer, and energy confining layer are individually controlled to achieve precise frequency distribution, then the frequency distribution can be optimized, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent changes the physical and chemical parameters of the IDT electrode by forming an oxide layer with specific thickness ratios (0.011≤to/te≤0.333). This oxidation process modifies the electrode's acoustic impedance and electromechanical coupling characteristics, enabling precise frequency distribution control through a single parameter adjustment rather than controlling multiple layer thicknesses individually.
Solution Approach 2:
The patent creates a composite electrode structure by forming an oxide layer on top of the metal electrode layer. This composite structure combines the high conductivity of metal (Al, Cu, Ti, W, Mo, Pt, or Au) with the acoustic properties of the oxide material, achieving both electrical performance and precise frequency control in a single integrated component.
2Manufacturing precision
If the thickness of the oxide electrode layer is increased to adjust resonant frequency, then the frequency distribution improves, but the peak loss and bandwidth may exceed performance tolerances
Solution Approach 1:
The patent precisely controls the oxide layer thickness within a specific ratio range (0.011≤to/te≤0.333) to optimize the balance between resonant frequency adjustment and performance maintenance. This parameter optimization ensures that the frequency distribution is improved while keeping peak loss and bandwidth within acceptable tolerances.
Solution Approach 2:
The patent applies a controlled oxidation process that creates a partial oxide layer rather than complete oxidation. This partial action allows sufficient frequency adjustment while avoiding excessive oxide thickness that would degrade performance, achieving the optimal balance between frequency control and performance preservation.
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 effectively controls the resonant frequency and bandwidth of surface acoustic wave devices, ensuring performance within specified tolerances by adjusting the oxide electrode layer thickness within a specific range (0.011≤to/te≤0.333), thereby enhancing the devices' frequency distribution and stability.
Implementation Method 1
an oxide electrode layer formed on the upper surface of the upper electrode layer by oxidation of the upper electrode layer
Implementation Method 2
the second oxide electrode layer may be formed through an oxidation process by irradiating the upper electrode layer with an ion beam
Data Source
AI summary
Provided are a surface acoustic wave device including IDT electrodes having an oxide electrode layer formed therein, and a method for fabricating the same. The surface acoustic wave device include a piezoelectric substrate and a plurality of IDT electrodes formed on the piezoelectric substrate, wherein each of the plurality of IDT electrodes includes: a main electrode layer formed on the upper surface of the piezoelectric substrate; an upper electrode layer formed on the main electrode layer; and an oxide electrode layer formed on the upper surface of the upper electrode layer by oxidation of the upper electrode layer, and wherein the thickness (te) of each of the plurality of IDT electrodes satisfies 0.011≤to/te≤0.333 with respect to the thickness (to) of the oxide electrode layer.