Stepped Composite Substrate for Acoustic Wave Spurious Signal Control
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Solution Overview
Problem
Acoustic wave devices face challenges in reducing spurious signals due to acoustic wave leakage and reflection at the side surfaces of the composite substrate, which affects the frequency characteristics and efficiency of the device.
Innovation Solution
The acoustic wave device incorporates a composite substrate with a step portion on its side surfaces, featuring a step-like shape that ascends from the support substrate to the piezoelectric film, which helps scatter and reflect unwanted acoustic waves, reducing spurious signals and improving the device's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic wave devices use a composite substrate with multilayer film, then the device can achieve better acoustic wave confinement and performance, but spurious signals are generated due to acoustic wave leakage and reflection at the side surfaces
Solution Approach 1:
The patent introduces a step portion structure that creates multiple height levels (dimensions) on the side surface of the composite substrate. This dimensional change transforms the flat side surface into a stepped profile with different elevation levels, which effectively scatters and reflects acoustic waves to reduce spurious signals while maintaining acoustic wave confinement in the functional layers
2Ease of manufacture
If the side surface is made flat and uniform, then manufacturing is simpler, but acoustic waves leak and reflect at the side surfaces causing spurious signals
Solution Approach 1:
The side surface is segmented into multiple discrete step portions at different height levels rather than being a continuous flat surface. This segmentation creates distinct zones that interact with acoustic waves differently, scattering and reflecting them to reduce spurious signals while maintaining manufacturing feasibility through standardized layer deposition processes
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 step portion effectively reduces spurious signals by scattering and reflecting unwanted acoustic waves, leading to improved frequency characteristics and a potential size reduction of the acoustic wave device.
Implementation Method 1
The step portion has a step-like shape with two or more steps ascending from the support substrate side to the piezoelectric film side in a direction from an outside to an inside with respect to the side surface... effectively reduces spurious signals by scattering and reflecting unwanted acoustic waves
Implementation Method 2
The step portion has a step-like shape with two or more steps ascending from the support substrate side to the piezoelectric film side in a direction from an outside to an inside with respect to the side surface... effectively reduces spurious signals by scattering and reflecting unwanted acoustic waves
Implementation Method 3
An acoustic wave device includes a composite substrate and an excitation electrode located on an upper surface of the composite substrate... The piezoelectric film overlaps the upper surface of the multilayer film. The excitation electrode is located on an upper surface of the piezoelectric film
Data Source
AI summary
An acoustic wave device includes a composite substrate and an excitation electrode located on an upper surface of the composite substrate. The composite substrate includes a support substrate, a multilayer film, and a piezoelectric film overlapping the upper surface of the multilayer film. The multilayer film includes a plurality of acoustic films stacked on an upper surface of the support substrate. Adjacent ones of the acoustic films in a direction in which the acoustic films are stacked are made of different materials. The excitation electrode is located on an upper surface of the piezoelectric film. A side surface of the composite substrate includes a step portion. The step portion has a step-like shape with two or more steps ascending from the support substrate side to the piezoelectric film side in a direction from an outside to an inside with respect to the side surface.