Acoustic Wave Device Resonance Frequency Adjustment

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Solution Overview

Problem

Existing acoustic wave devices using piezoelectric thin-film resonators face challenges in efficiently adjusting resonance frequencies due to material limitations and increased production costs associated with forming multiple addition films, and require etching selectivity that restricts the choice of materials for addition films.

Innovation Solution

The acoustic wave device incorporates a first addition film between the piezoelectric thin-film and the upper electrode in the resonance portion, with a shape different from the resonance portion, allowing for adjustable resonance frequencies without the need for multiple addition films and enabling a wider selection of materials by ensuring etching selectivity only to the piezoelectric thin-film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple addition films are formed to achieve different resonance frequencies, then resonators with different resonance frequencies can be realized, but production cost increases

Engineering Contradiction:

Improveresonance frequency adjustment rangeVSAvoidproduction cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The addition film is divided into multiple layers (first addition film and second addition film) with different materials and functions. The first addition film provides etching selectivity, while the second addition film adjusts resonance frequency, allowing independent optimization of each layer's thickness and material properties to achieve different resonance frequencies without forming multiple complete addition films

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the addition film structure have different materials and thicknesses tailored to specific functions. The first addition film has etching selectivity to the upper electrode, while the second addition film has thickness optimized for resonance frequency adjustment, enabling cost-effective production of resonators with different frequencies

Inventive Principle:

Principle #3Local quality

2Device complexity

If a single-layer addition film is used, then the structure is simple, but the film thickness range for maintaining resonance performance is limited

Engineering Contradiction:

Improveaddition film structureVSAvoidfilm thickness adjustment range

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The addition film is divided into multiple layers with different thicknesses that can be independently optimized. The first addition film has a thickness optimized for etching selectivity, while the second addition film has a thickness optimized for resonance frequency adjustment, collectively providing a broader adjustable range

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multi-layer addition film structure combines different materials with complementary properties. This composite structure enables broader resonance frequency adjustment range while maintaining structural simplicity in the overall device architecture

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

This configuration allows for arbitrary selection of resonance frequencies in piezoelectric thin-film resonators, reducing production costs and expanding material options while maintaining resonance performance, and improves the orientation and characteristics of the piezoelectric thin-film.

Implementation Method 1

an acoustic wave device using a piezoelectric thin-film resonator... The resonance frequency of the piezoelectric thin-film resonator depends on the thickness of a portion in which the upper and lower electrodes face each other through the piezoelectric thin-film

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS8749320B2Acoustic wave device and method for manufacturing the same

Publication Date: 2014.06.10 TAIYO YUDEN KK

AI summary

An acoustic wave device includes piezoelectric thin-film resonators, each of which includes: a substrate; a piezoelectric thin-film on the substrate; an lower electrode provided on a first surface of the piezoelectric film; an upper electrode provided on a second surface of the piezoelectric film opposite to the first surface; and a first addition film that is provided in a resonance portion in which the lower electrode and the upper electrode face each other through the piezoelectric film and is located between the piezoelectric thin-film and the upper electrode, the first addition film having a shape different from that of the resonance portion.