Elastic Wave Electrode Groove Layout for Leakage Trapping

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Elastic wave devices struggle to trap waves propagating in directions other than the primary propagation direction, leading to leakage of elastic waves outside the device.

Innovation Solution

Incorporating grooves along the primary propagation direction on the piezoelectric substrate, with IDT electrodes and an intermediate layer, to reflect and trap waves propagating perpendicular to the primary direction, utilizing a combination of materials and layer structures to optimize acoustic velocity and impedance for efficient wave trapping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If grooves are provided only at outer side portions outside IDT electrodes to reflect waves in the propagation direction, then waves propagating in that direction are trapped, but waves propagating in other directions leak to the outside

Engineering Contradiction:

Improveleakage of elastic wavesVSAvoidstructure of grooves

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The groove structure is segmented into multiple portions: first grooves at outer side portions for reflecting waves in the propagation direction, and second grooves at side portions for reflecting waves in other directions. This segmentation allows each groove set to specialize in reflecting waves from different directions, comprehensively reducing energy leakage without requiring a completely complex alternative structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention extends the groove arrangement from one dimension (only outer side portions) to two dimensions (outer side portions and side portions). By adding grooves in the direction perpendicular to the propagation direction, the structure captures and reflects waves propagating in multiple directions, effectively reducing energy leakage in all directions around the IDT electrode.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If grooves are extended deeply into the piezoelectric substrate to improve wave reflection, then reflection efficiency increases, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvewave reflection efficiencyVSAvoidgroove fabrication

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of extending grooves deeply throughout the entire piezoelectric substrate, the invention uses partial action by limiting groove depth to only where necessary for effective wave reflection. The grooves extend from the surface to a depth sufficient to reflect elastic waves, but not unnecessarily deep, thereby reducing manufacturing complexity and cost while maintaining adequate reflection efficiency.

Inventive Principle:

Principle #16Partial or excessive action

3Loss of energy

If multiple grooves are provided on all sides of IDT electrode to trap waves in all directions, then wave leakage is reduced, but device complexity increases

Engineering Contradiction:

Improveelastic wave leakageVSAvoidgroove configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

Different groove configurations are applied to different locations around the IDT electrode based on local requirements. First grooves are provided at outer side portions where waves propagate in the primary direction, while second grooves are provided at side portions to address waves propagating in perpendicular directions. This localized differentiation reduces overall complexity compared to a uniform groove pattern all around.

Inventive Principle:

Principle #3Local quality

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

Significantly reduces leakage of elastic waves by effectively reflecting and trapping waves in all directions, enhancing the efficiency of wave energy containment within the device.

Implementation Method 1

elastic waves that propagate in a direction different from the elastic wave propagation direction are reflected by the groove

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS10879870B2Elastic wave device, front-end circuit, and communication device

Publication Date: 2020.12.29 MURATA MFG CO LTD

AI summary

An elastic wave device includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate. The IDT electrode includes a busbar electrode extending in an elastic wave propagation direction and electrode fingers connected to the busbar electrode and extending in a direction perpendicular or substantially perpendicular to the elastic wave propagation direction. The piezoelectric substrate includes a groove extending along the elastic wave propagation direction. The groove is provided on a side across the busbar electrode in the perpendicular or substantially perpendicular direction from a side at which the electrode fingers are located.