Al Alloy Interdigital Electrode for Elastic Wave Resonator Linearity
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Solution Overview
Problem
Conventional elastic wave resonators with Al film interdigital transducer electrodes suffer from signal non-linearity issues, leading to increased non-linear signals and decreased reception sensitivity in duplexers.
Innovation Solution
The use of a piezoelectric substrate with an interdigital transducer electrode featuring a first electrode layer made of Al or its alloy and a second electrode layer from metals like Ti, Pt, Mo, W, Au, Cu, Ag, or NiCr, where the distortion S4 component is minimized to 1.4×10−3 or less, reducing signal non-linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the interdigital transducer electrode is made of Al film, then the manufacturing cost is reduced and ease of manufacture is improved, but signal linearity deteriorates and non-linear signals increase
Solution Approach 1:
The patent applies composite materials by combining Al film with other metal films (such as Ti, Pt, Mo, W, Au, Cu, Ag, or NiCr) to form a multi-layer interdigital transducer electrode structure. This composite structure maintains the ease of manufacture associated with Al film while eliminating the signal non-linearity problems through the addition of other metal layers that suppress distortion S4 components.
2Reliability
If a multi-layer electrode structure is implemented to reduce non-linear signals, then signal linearity is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the thickness parameters of each layer in the multi-layer electrode structure. By optimizing the thickness of the Al film and the additional metal film(s), the structure achieves reduced non-linear signals while keeping the added complexity minimal and manageable through standardized thin-film deposition processes.
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 significantly reduces or prevents non-linear signals, thereby enhancing the linearity of signals and maintaining or improving reception sensitivity in elastic wave filters and duplexers.
Implementation Method 1
an elastic wave resonator in which an interdigital transducer electrode is provided on a piezoelectric substrate
Implementation Method 2
An SH wave is used as a propagated elastic wave
Data Source
AI summary
An elastic wave resonator includes an interdigital transducer electrode provided on a piezoelectric substrate and including a first electrode layer made of Al or an alloy with Al as its primary component and including a first main surface on a side where the piezoelectric substrate is located and a second main surface on the opposite side from the first main surface. An SH wave is used as a propagated elastic wave. When a resonant frequency of the elastic wave resonator is fr and an anti-resonant frequency of the elastic wave resonator is fa, a minimum value of an absolute value of a distortion component in the first main surface calculated through a two-dimensional finite element method is about 1.4×10−3 or less at a frequency f expressed as:f=fr+0.06×bw, where bw is fa−fr.