Acoustic Wave Resonator Structure for Crack-Free Hollow Support
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Solution Overview
Problem
The existing acoustic wave devices with a hollow between a support substrate and a piezoelectric layer are prone to spurious emission, which can cause cracks in the piezoelectric layer.
Innovation Solution
Incorporating a reinforcing film over the piezoelectric layer and through holes that communicate with the hollow, positioned to overlap with the interdigital transducer electrode, to prevent cracks and reduce spurious emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a hollow is provided between the support substrate and piezoelectric layer to reduce spurious emission, then spurious emission is reduced, but cracks may occur in the piezoelectric layer due to stress concentration
Solution Approach 1:
A reinforcing film is formed on the piezoelectric layer at positions corresponding to the hollow regions before the device operates. This reinforcing film acts as a preventive measure to cushion and distribute the stress that would otherwise concentrate at the hollow boundaries, preventing crack formation while maintaining the spurious emission reduction benefit of the hollow structure
Solution Approach 2:
The device uses a composite structure combining the piezoelectric layer with a reinforcing film made of different material properties. The reinforcing film has higher mechanical strength and different elastic moduli, creating a composite system that maintains the acoustic performance of the piezoelectric layer while adding mechanical reinforcement to prevent cracks at the hollow interfaces
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 solution effectively prevents cracks in the piezoelectric layer and minimizes spurious emission, enhancing the stability and performance of the acoustic wave device.
Implementation Method 1
a piezoelectric layer on the support substrate
Implementation Method 2
an interdigital transducer electrode on the piezoelectric layer and including a plurality of first electrode fingers and a plurality of second electrode fingers
Data Source
AI summary
An acoustic wave device includes a support substrate having a thickness in a first direction, a piezoelectric layer on the support substrate, an interdigital transducer electrode on the piezoelectric layer and including first and second electrode fingers, the first electrode fingers extending in a second direction crossing the first direction, the second electrode fingers extending in the second direction and facing the first electrode fingers in a third direction orthogonal or substantially orthogonal to the second direction, and a reinforcing film on the piezoelectric layer. The support substrate and the piezoelectric layer include a hollow therebetween at a position overlapping the interdigital transducer electrode in the first direction. At least one through hole penetrates the piezoelectric layer at a position not overlapping the interdigital transducer electrode in the first direction, and the through hole communicates with the hollow. The reinforcing film overlaps the hollow in the first direction.