Bonded Acoustic Wave Structure With Refractive-Index Multilayers
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Solution Overview
Problem
Acoustic wave devices, particularly in the high frequency range (5G applications), face challenges in achieving a sufficient Q-value due to the limitations of existing multilayer films like SiO2/Ta2O5 between the supporting substrate and piezoelectric material substrate.
Innovation Solution
A multilayer film structure is introduced, comprising alternating layers of silicon oxides and metal oxides, where the refractive indices of the metal oxide layers are higher than those of the silicon oxides and differ from each other, enhancing the Q-value performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a multilayer film of SiO2 and Ta2O5 is inserted between the supporting substrate and piezoelectric material substrate, then acoustic wave reflection is improved for reducing loss, but the Q value improvement is not sufficient in high frequency range (5G application of 3.5 to 6 GHz)
Solution Approach 1:
The patent changes the refractive index parameter of the multilayer film by replacing Ta2O5 with HfO2, which has a higher refractive index. This parameter change optimizes the acoustic wave reflection characteristics specifically for high frequency ranges (3.5 to 6 GHz), thereby improving the Q value while maintaining energy loss reduction
Solution Approach 2:
The patent uses a composite multilayer film structure combining SiO2 and HfO2 layers. This composite material approach creates optimized acoustic impedance matching and reflection characteristics that are specifically effective for high frequency 5G applications, resolving the insufficiency of the SiO2-Ta2O5 combination
2Loss of energy
If a multilayer film structure is used to reflect acoustic waves, then acoustic wave loss is reduced, but the Q value improvement remains insufficient in high frequency range due to quality differences in multilayer films
Solution Approach 1:
The patent specifies precise refractive index parameters for each layer (SiO2 with lower refractive index, HfO2 with higher refractive index) to optimize the multilayer film quality for high frequency applications. This parameter control ensures consistent manufacturing quality that delivers the required Q value improvement in the 3.5 to 6 GHz range
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 significantly improves the Q-value, especially in the high frequency range, by modulating the refractive indices effectively, resulting in a higher Q-value for acoustic wave devices.
Implementation Method 1
an acoustic wave leaked from the piezoelectric material substrate toward the supporting substrate is reflected at the multilayer film for reducing the loss
Implementation Method 2
a piezoelectric substrate propagating a surface acoustic wave
Data Source
AI summary
A bonded body includes a supporting substrate, piezoelectric material substrate and a multilayer film between the supporting substrate and piezoelectric material substrate. The multilayer film includes a lamination structure having a first layer, second layer, third layer and fourth layer in that order. The first layer and third layer are composed of silicon oxides, and the second layer and fourth layer are composed of metal oxides. The refractive index of the second layer is higher than the refractive index of the first layer and refractive index of the third layer. The refractive index of the second layer is different from the refractive index of the fourth layer.