Acoustic Wave Dielectric Layer Layout for Leakage and Coupling Balance

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Solution Overview

Problem

Surface acoustic wave devices experience quality factor degradation due to transverse leakage of acoustic energy, which also leads to a significant reduction in the coupling factor when using a silicon dioxide layer between the interdigital transducer electrode and the piezoelectric layer.

Innovation Solution

A selectively positioned intermediate dielectric layer is used between the piezoelectric layer and the interdigital transducer electrode, partially covering areas under the edge and gap regions, to suppress transverse leakage while maintaining a high coupling factor, with the dielectric layer being silicon dioxide and having a thickness between 0.005 and 0.02 times the acoustic wave wavelength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a silicon dioxide layer is positioned between the interdigital transducer electrode and the piezoelectric layer to suppress transverse leakage, then the quality factor is improved, but the coupling factor is significantly reduced

Engineering Contradiction:

Improvequality factorVSAvoidcoupling factor

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies local quality by selectively positioning the silicon dioxide dielectric layer only in specific regions (edge region and gap region) rather than uniformly across the entire device. This localized approach suppresses transverse leakage in critical areas while preserving strong coupling in the center region where the interdigital transducer electrode directly contacts the piezoelectric layer, thus resolving the contradiction between improving quality factor and maintaining coupling factor

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If a dielectric layer is positioned between the piezoelectric layer and the interdigital transducer electrode to suppress transverse leakage, then acoustic energy confinement is improved, but the electromechanical coupling is weakened

Engineering Contradiction:

Improvetransverse leakageVSAvoidelectromechanical coupling

Core Design Contradiction:

Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The dielectric layer is strategically positioned only in the edge region and gap region where transverse leakage occurs, while the center region maintains direct contact between the interdigital transducer electrode and piezoelectric layer. This localized differentiation confines acoustic energy effectively without compromising the strong electromechanical coupling needed for efficient energy conversion

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The silicon dioxide layer acts as an intermediary element that selectively mediates the interaction between the piezoelectric layer and interdigital transducer electrode. It provides acoustic energy confinement where needed (edge and gap regions) while allowing strong coupling to persist in the center region, thus balancing energy confinement and coupling efficiency

Inventive Principle:

Principle #24Intermediary (Mediator)

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 improves the quality factor of the surface acoustic wave device by reducing transverse leakage while preserving a high coupling factor, enhancing the performance of both shear horizontal and Rayleigh mode devices.

Implementation Method 1

The dielectric layer positioned so as to suppress transverse leakage of acoustic energy generated by the acoustic wave device

Methodology Applied

Scientific EffectTransverse leakage suppression:

Implementation Method 2

A surface acoustic wave device can be configured to generate, for example, a Rayleigh mode surface acoustic wave or a shear horizontal mode surface acoustic wave

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS20230032325A1Acoustic wave device with dielectric layer for transverse leakage suppression

Publication Date: 2023.02.02 SKYWORKS SOLUTIONS INC

AI summary

An acoustic wave device is disclosed. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode over the piezoelectric layer, a temperature compensation layer over the interdigital transducer electrode, and a dielectric layer positioned partially between the piezoelectric layer and the interdigital transducer electrode. The interdigital transducer electrode includes an active region that has a center region and an edge region, a bus bar, and a gap region between the active region and the bus bar. At least a portion of the center region is in direct contact with the piezoelectric layer.