Multilayer SAW Resonator Structure for Coupling and Temperature Stability

Solution Overview

Problem

Achieving a high temperature coefficient of frequency and quality factor while maintaining a high coupling coefficient in multi-layer piezoelectric substrate surface acoustic wave devices is challenging.

Innovation Solution

A surface acoustic wave resonator is designed with a multi-layer piezoelectric substrate comprising a base layer, an intermediate layer of silicon dioxide, and a piezoelectric layer of lithium niobate with a rotated cut angle, along with interdigital transducer electrodes made from materials like aluminum and molybdenum, and coated with silicon nitride and silicon dioxide, to optimize the coupling coefficient and temperature stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a multi-layer piezoelectric substrate structure is used to achieve high coupling coefficient, then the coupling coefficient is improved, but it becomes challenging to achieve high temperature coefficient of frequency and quality factor

Engineering Contradiction:

Improvecoupling coefficientVSAvoidtemperature coefficient of frequency

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The piezoelectric substrate is divided into multiple layers with different materials and orientations. The first piezoelectric layer has a first orientation while the second piezoelectric layer has a second orientation different from the first, allowing each layer to contribute differently to the overall device performance, thereby achieving high coupling coefficient while maintaining temperature stability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The device uses a composite structure combining multiple piezoelectric layers with different crystal orientations and potentially different materials. This composite approach allows the device to achieve high coupling coefficient through the piezoelectric effect while the specific orientation combination compensates for temperature variations, achieving both high reliability and temperature stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If a multi-layer piezoelectric substrate structure is used to achieve high coupling coefficient, then the coupling coefficient is improved, but it becomes challenging to achieve high quality factor

Engineering Contradiction:

Improvecoupling coefficientVSAvoidquality factor

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The piezoelectric substrate is divided into multiple layers with different materials and orientations. The first piezoelectric layer has a first orientation while the second piezoelectric layer has a second orientation different from the first, allowing each layer to contribute differently to the overall device performance, thereby achieving high coupling coefficient while maintaining temperature stability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The device uses a composite structure combining multiple piezoelectric layers with different crystal orientations and potentially different materials. This composite approach allows the device to achieve high coupling coefficient through the piezoelectric effect while the specific orientation combination compensates for temperature variations, achieving both high reliability and temperature stability

Inventive Principle:

Principle #40Composite materials

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 design enhances the coupling coefficient and temperature stability, resulting in improved power handling and durability of the acoustic wave devices, with a wider filter passband under high temperature conditions.

Implementation Method 1

A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Data Source

PatentUS20240396517A1Acoustic wave devices with multilayer piezoelectric substrate

Publication Date: 2024.11.28 SKYWORKS SOLUTIONS INC

AI summary

An acoustic wave resonator is disclosed. The acoustic wave resonator includes a multi-layer piezoelectric substrate including a base layer, an intermediate layer, and a piezoelectric layer with lithium niobate (LiNbO3) having a cut angle ranging from 20 to 40 degrees. The acoustic wave resonator includes interdigital transducer electrodes that are in electrical communication with the piezoelectric layer.