ScAlN Piezoelectric Slit Tapering for Stable Detection Sensitivity

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Solution Overview

Problem

Conventional methods for manufacturing piezoelectric elements using scandium aluminum nitride (ScAlN) face challenges in forming appropriate slits due to its difficult-to-etch nature, leading to variations in vibration region shape and decreased detection sensitivity.

Innovation Solution

A piezoelectric element design featuring a support with a vibrating portion comprising scandium aluminum nitride (ScAlN) piezoelectric film and electrode film, where slits are formed with a tapered portion angled between 39 to 81 degrees, allowing for precise slit formation and maintaining detection sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional etching methods are used to form slits in scandium aluminum nitride piezoelectric film, then the manufacturing process can be completed, but the slit formation accuracy deteriorates due to the difficult-to-etch nature of ScAlN

Engineering Contradiction:

Improveslit formation accuracyVSAvoidetching difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent introduces a tapered portion in the slit with a specific angle range (39 to 81 degrees) to modify the etching parameters. This geometric parameter change enables accurate slit formation in ScAlN by optimizing the etching process, transforming the difficult etching task into a controllable process that achieves both manufacturing precision and ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If slits are formed in the piezoelectric film to create vibration regions, then the piezoelectric element functionality is achieved, but variations in vibration region shape occur leading to decreased detection sensitivity

Engineering Contradiction:

Improvedetection sensitivityVSAvoidvibration region shape consistency

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

By specifying the tapered portion angle within the range of 39 to 81 degrees, the patent controls the etching process to produce consistent vibration region shapes. This parameter control ensures that all vibration regions are formed with uniform geometry, eliminating shape variations and maintaining high detection sensitivity across all piezoelectric elements.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the piezoelectric film material is changed to scandium aluminum nitride to improve piezoelectric properties, then detection performance is enhanced, but the etching workability deteriorates

Engineering Contradiction:

Improvedetection performanceVSAvoidetching workability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent resolves the workability issue of ScAlN etching by introducing the tapered portion geometry with angle 39 to 81 degrees. This structural parameter change allows the etching process to work effectively with ScAlN material, maintaining both the superior piezoelectric properties and acceptable manufacturing workability.

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 design suppresses deterioration of workability and detection sensitivity by ensuring accurate slit formation, enhancing the performance of piezoelectric elements.

Implementation Method 1

an electrode film connected to the piezoelectric film to generate electric charges by deformation and to extract the electric charges generated

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12487137B2Piezoelectric element, piezoelectric device, and method of manufacturing piezoelectric element

Publication Date: 2025.12.02 DENSO CORP

AI summary

A piezoelectric element includes a plurality of vibration regions that are separated from each other by a slit, and the slit is formed to have a tapered portion that is tapered from a first surface of the vibration regions on an opposite side to a support to a second surface opposite to the first surface. An electrode film is positioned inside than the slit when being viewed from a normal direction orthogonal to the first surface, and an angle formed by a side surface of the tapered portion in the vibration region and a surface parallel to the first surface is in a range of 39 to 81 degrees.