Acoustic Resonator Thickness Layout for Consistent Frequency Adjustment

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Solution Overview

Problem

Existing acoustic wave devices face variations in frequency adjustment due to manufacturing errors in piezoelectric layer thickness, requiring individual trimming of frequency adjustment films for each resonator, leading to inconsistent frequency adjustments.

Innovation Solution

The acoustic wave device is designed with first and second resonators sharing a piezoelectric layer, where the first resonator has a greater thickness than the second, and their dielectric films are configured to satisfy a specific thickness ratio, allowing simultaneous trimming to reduce variations in frequency adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If individual trimming of frequency adjustment films is performed for each resonator to compensate for piezoelectric layer thickness deviations, then frequency adjustment precision is improved, but manufacturing complexity and time consumption increase

Engineering Contradiction:

Improvefrequency adjustment precisionVSAvoidmanufacturing efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent merges multiple trimming operations into a single unified trimming process. By designing resonators with different thicknesses on the same piezoelectric layer and applying a single trimming amount to the frequency adjustment film, the patent consolidates what would otherwise require multiple individual trimming operations, thereby improving productivity while maintaining frequency adjustment precision

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent segments the piezoelectric layer into multiple resonator portions with different thicknesses (first resonator portion with thickness tp1, second resonator portion with thickness tp2). This segmentation allows each resonator to have its own frequency characteristics while sharing the same frequency adjustment film, enabling unified trimming to affect multiple resonators simultaneously

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If uniform thickness frequency adjustment film is used for all resonators, then manufacturing simplicity is maintained, but frequency adjustment variation between resonators increases

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidfrequency adjustment consistency

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating resonator portions with different local thickness characteristics (tp1 for first resonator, tp2 for second resonator) on the same piezoelectric layer. This allows each resonator to have optimized local properties for its specific frequency requirements while maintaining a uniform frequency adjustment film structure, achieving both manufacturing simplicity and frequency adjustment consistency

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the thickness parameter of the piezoelectric layer locally for different resonator portions. By varying the thickness (tp1 ≠ tp2) while keeping the frequency adjustment film uniform, the patent achieves different resonant frequencies for different resonators, and the relationship ts1/tp1 ≤ ts2/tp2 ensures that frequency adjustment consistency is maintained across resonators with different thicknesses

Inventive Principle:

Principle #35Parameter changes

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 reduces the variation in the ratio of trimmed amounts for dielectric films across resonators, facilitating consistent frequency adjustment and improving productivity by allowing simultaneous trimming.

Implementation Method 1

a piezoelectric substrate including a piezoelectric layer... configured to use a thickness resonance mode

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a first dielectric film on the piezoelectric layer and covering the first functional electrode, and a second dielectric film on the piezoelectric layer and covering the second functional electrode

Methodology Applied

Scientific EffectDielectric property: Dielectric

Data Source

PatentUS12451865B2Acoustic wave device

Publication Date: 2025.10.21 MURATA MFG CO LTD

AI summary

An acoustic wave device is provided that includes a piezoelectric layer and first and second resonators. The first resonator includes a first functional electrode and a first dielectric film on the piezoelectric layer. The second resonator includes a second functional electrode and a second dielectric film on the piezoelectric layer. The piezoelectric layer includes first and second resonator portions respectively including portions of the first and second resonators. Moreover, a resonant frequency of the first resonator is lower than that of the second resonator. A thickness of the first resonator portion is greater than that of the second resonator portion, and ts1/tp1≤ts2/tp2 is satisfied, where tp1, tp2, ts1, and ts2 are respectively thicknesses of the first and second resonator portions and the first and second dielectric films.