IDT Electrode Width Control for Suppressing Acoustic Wave Spurious Modes
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Solution Overview
Problem
Acoustic wave devices with interdigital transducers (IDT) electrodes face issues with spurious responses of higher order modes in frequency bands higher than the excitation mode, leading to deteriorated device characteristics.
Innovation Solution
The acoustic wave device includes a support substrate, a piezoelectric layer, and an IDT electrode with the intersecting width of the electrode fingers set to be equal to or smaller than about 5λ, along with a low acoustic velocity film and a high acoustic velocity film to reduce spurious responses and improve Q values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IDT electrode is formed on the piezoelectric film with conventional electrode finger dimensions, then the device can operate at the excitation mode frequency, but spurious responses of higher order modes are generated in frequency bands higher than the excitation mode
Solution Approach 1:
The patent applies parameter changes by specifically controlling the intersecting width of electrode fingers to be equal to or smaller than about 5λ. This dimensional parameter modification of the IDT electrode structure effectively suppresses the generation of spurious responses from higher order modes while maintaining the excitation mode operation, thereby resolving the technical contradiction between device reliability and harmful spurious responses.
2Object-generated harmful factors
If the intersecting width of electrode fingers is reduced to suppress higher order modes, then spurious responses are reduced, but the device complexity increases due to precise dimensional control requirements
Solution Approach 1:
The patent establishes a clear quantitative parameter threshold (intersecting width ≤ 5λ) that provides a straightforward design guideline. This parameter specification simplifies the design process by giving engineers a concrete target value, reducing the complexity associated with precise dimensional control while still achieving effective suppression of spurious responses.
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 spurious responses of higher order modes, enhancing the device's characteristics and Q values, thereby improving the acoustic wave device's performance.
Implementation Method 1
a piezoelectric layer (3), and an interdigital transducer (IDT) electrode (6) The IDT electrode (6) is provided on the piezoelectric layer (3)
Implementation Method 2
The piezoelectric layer (3) is provided over the support substrate (2) in a thickness direction (first direction D1) of the support substrate (2)
Data Source
AI summary
An acoustic wave device includes a support substrate, a piezoelectric layer, and an IDT electrode. The piezoelectric layer is over the support substrate. The IDT electrode is on the piezoelectric layer, and includes a plurality of electrode fingers. An intersecting width of the plurality of electrode fingers is equal to or smaller than about 5λ.