Elastic Wave Resonator Interface Layer for Stable Filter Resonance
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Solution Overview
Problem
Existing elastic wave elements face challenges in reducing signal loss and improving low-temperature characteristics, particularly when the thickness of the piezoelectric body is reduced, which affects resonance characteristics due to interface state variations between the piezoelectric body and the support substrate.
Innovation Solution
The elastic wave element incorporates a first intermediate layer with a lower resistivity than the piezoelectric body, formed by activating the surface of the piezoelectric body and the support substrate, which reduces the influence of the interface state on resonance characteristics and improves filter characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the piezoelectric body is reduced, then the resonance characteristics are improved, but the influence of interface state variations between the piezoelectric body and support substrate increases
Solution Approach 1:
A first intermediate layer is introduced between the piezoelectric body and the support substrate. This intermediate layer acts as a mediator that reduces the influence of interface state variations on the resonance characteristics of the piezoelectric body, thereby improving reliability while maintaining the benefits of reduced thickness.
2Reliability
If a first intermediate layer with lower resistivity is introduced between the piezoelectric body and support substrate, then the influence of interface state on resonance characteristics is reduced, but the device complexity increases
Solution Approach 1:
The first intermediate layer is designed with specific parameter characteristics (lower resistivity than the piezoelectric body) to achieve the desired effect of reducing interface state influence. By controlling the resistivity parameter of the intermediate layer, the system achieves improved reliability without excessive complexity increase.
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 spuriousness in stop bands, enhances the electrical characteristics of filters, and improves low-temperature stability by optimizing the interface between the piezoelectric body and the support substrate.
Implementation Method 1
a piezoelectric substrate including a piezoelectric body and an IDT electrode with a plurality of electrode fingers arranged at predetermined pitches on the piezoelectric body
Data Source
AI summary
To achieve an elastic wave element with excellent electrical characteristics. An elastic wave resonator includes a piezoelectric substrate including a piezoelectric body and an IDT electrode, a support substrate, and a first intermediate layer. In the first intermediate layer, an atomic ratio of a metal element is larger than an atomic ratio of a metal element in the piezoelectric body, and an atomic ratio of oxygen is smaller than an atomic ratio of oxygen in the piezoelectric body. A thickness of the piezoelectric body is equal to or less than five times a maximum pitch of electrode fingers of the IDT electrode.