IDT Electrode Dielectric Layout for Surge-Resistant Acoustic Waves
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Solution Overview
Problem
Acoustic wave devices with low acoustic velocity regions are prone to surge breakdown due to narrow gaps between electrode fingers, which is a result of larger electrode finger widths in these regions.
Innovation Solution
The design includes a piezoelectric substrate with an IDT electrode and a dielectric film, where the electrode fingers have wider widths in edge regions than in the central region, and the dielectric film is thicker in these edge regions, creating a higher acoustic velocity on the outer sides of the edge regions, thereby reducing the likelihood of surge breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electrode finger width is increased in low acoustic velocity regions, then acoustic velocity is reduced, but gap between electrode fingers becomes narrow causing surge breakdown
Solution Approach 1:
The patent applies local quality by making the dielectric film thickness vary across different regions of the IDT electrode. Specifically, the dielectric film is thicker in the edge regions (first and second low acoustic velocity regions) and thinner in the central region. This localized variation in dielectric film thickness compensates for the narrow gap between electrode fingers in the edge regions, preventing surge breakdown while maintaining the desired acoustic velocity distribution.
Solution Approach 2:
The dielectric film acts as an intermediary element between the electrode fingers. By adjusting the dielectric film thickness in different regions, the patent mediates the electrical field distribution and prevents surge breakdown in the narrow gap regions without requiring changes to the electrode finger geometry or spacing.
2Stability of the object's composition
If electrode finger width is increased to create low acoustic velocity regions, then piston mode is achieved, but manufacturing complexity increases due to variable dielectric film thickness
Solution Approach 1:
The patent implements local quality by defining specific regions (central region and edge regions) with different dielectric film thicknesses. This localized approach achieves the complex acoustic velocity distribution needed for piston mode stability while keeping the overall structure manageable through clear regional definitions.
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 reduces the occurrence of surge breakdown and transverse-mode ripple while maintaining a higher acoustic velocity difference without significantly increasing electrode finger widths, enhancing the performance of acoustic wave devices.
Implementation Method 1
an acoustic wave device includes a piezoelectric substrate, an IDT electrode on the piezoelectric substrate
Implementation Method 2
an acoustic velocity in the first and second low acoustic velocity regions is lower than that in the central region
Data Source
AI summary
An acoustic wave device includes a dielectric film covering an IDT electrode. The IDT electrode includes first and second edge regions and first and second high acoustic velocity regions. The first and second edge regions are low acoustic velocity regions. The first and second high acoustic velocity regions are on outer sides of an intersecting width region where first and second electrode fingers are adjacent to each other in an acoustic wave propagation direction. A thickness of the dielectric film on the first and second edge regions is greater than that of the dielectric film on the first and second high acoustic velocity regions.