Acoustic Wave Support Structure to Limit IDT Wave Reflection
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Solution Overview
Problem
Acoustic wave devices suffer from deterioration of electrical characteristics due to unnecessary waves propagating on the surface of the piezoelectric substrate, which affects their performance.
Innovation Solution
The design incorporates a piezoelectric substrate with a support structure and a second support that does not overlap the intersecting region of the IDT electrodes, preventing unnecessary waves from being reflected and reducing electrical characteristic deterioration by ensuring the second support does not overlap the intersecting region when viewed from both the electrode extending and facing directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a support structure is added to the piezoelectric substrate, then structural stability is improved, but unnecessary waves are reflected causing electrical characteristic deterioration
Solution Approach 1:
The patent positions the second support structure to intentionally reflect unnecessary surface waves back toward the IDT electrode, converting the harmful reflection effect into a beneficial wave cancellation mechanism that suppresses spurious responses and improves electrical characteristics
2Reliability
If the second support is positioned to suppress unnecessary waves, then electrical characteristics are improved, but device complexity increases
Solution Approach 1:
The second support structure serves multiple functions simultaneously: it provides mechanical support to the piezoelectric substrate, acts as a reflector for unnecessary surface waves, and contributes to wave cancellation. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in device complexity while achieving improved electrical characteristics
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 or prevents the deterioration of electrical characteristics in acoustic wave devices by minimizing the reflection of unnecessary waves, thereby enhancing their performance.
Implementation Method 1
The piezoelectric substrate includes a piezoelectric layer and an IDT electrode. An interdigital transducer (IDT) electrode is provided on the upper surface of the piezoelectric substrate. A voltage is applied between a plurality of electrode fingers connected to one potential of the IDT electrode and a plurality of electrode fingers connected to the other potential. As a result, Lamb waves are excited.
Implementation Method 2
an acoustic wave device using Lamb waves as plate waves. In this acoustic wave device, a piezoelectric substrate is provided on a support. The piezoelectric substrate is made of LiNbO3 or LiTaO3. An interdigital transducer (IDT) electrode is provided on the upper surface of the piezoelectric substrate. A voltage is applied between a plurality of electrode fingers connected to one potential of the IDT electrode and a plurality of electrode fingers connected to the other potential. As a result, Lamb waves are excited.
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate including a support including a support substrate and a piezoelectric layer on the support and including first and second main surfaces, a functional electrode on the first or second main surface and including a pair of electrodes, a first support on the piezoelectric substrate and surrounding the functional electrode, at least one second support on the piezoelectric substrate in a portion surrounded by the first support, and a lid on the first and second supports. The second support does not overlap an intersecting region when viewed from an electrode extending direction and from an electrode facing direction.