SAW Interdigital Electrode Structure for Precise End Protrusion Alignment

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Solution Overview

Problem

Existing SAW devices face misalignment issues between protruding metal blocks and interdigital electrodes due to the photolithography process, leading to performance inconsistencies and clutter suppression inefficiencies.

Innovation Solution

A precise etching back method is employed to form interdigital electrodes with thicker end portions, creating protruding structures from a single material layer, ensuring vertical alignment and uniform thickness through the use of a protective layer and ion beam etching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If photolithography process is used to form protruding metal blocks, then metal blocks can be formed on interdigital electrodes, but misalignment occurs between metal blocks and electrodes leading to performance inconsistencies

Engineering Contradiction:

Improveformation of protruding metal blocksVSAvoidalignment between metal blocks and interdigital electrodes

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent merges the formation of protruding structures with the interdigital electrodes by etching the electrode material itself to create thicker end portions, eliminating the separate metal block formation process. This integration ensures perfect alignment between the protruding structures and electrodes while maintaining manufacturing feasibility through a unified etching process.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Instead of adding metal blocks onto the electrodes (conventional approach), the patent inverts the approach by selectively removing material to create protruding structures from the electrode material itself. This inversion of the formation methodology eliminates alignment issues inherent in additive processes like photolithography.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If uniform thickness interdigital electrodes are used, then fabrication is simplified, but clutter suppression efficiency is reduced

Engineering Contradiction:

Improvefabrication simplicityVSAvoidclutter suppression efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating non-uniform thickness in the interdigital electrodes, with thicker end portions and thinner central portions. This localized variation in geometry optimizes clutter suppression at the electrode ends while maintaining overall device functionality, demonstrating that non-uniform structures can simultaneously improve performance and remain manufacturable.

Inventive Principle:

Principle #3Local quality

3Reliability

If thicker end portions are formed to create protruding structures, then clutter suppression is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improveclutter suppressionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex multi-step fabrication processes (such as separate metal deposition and photolithography) with a unified etching process that directly creates the protruding structures from the interdigital electrode material. This substitution of the manufacturing mechanism maintains clutter suppression effectiveness while significantly reducing process complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method achieves accurate alignment and consistent performance by forming protruding structures from a unified material, enhancing clutter suppression and filter efficiency.

Implementation Method 1

etching the exposed portions of the protective layer, and etching the central portions and the intermediate portions of the interdigital electrodes to a preset thickness

Methodology Applied

Scientific EffectIon beam etching: Ion Beam

Data Source

PatentUS12476602B2Surface acoustic wave device and fabrication method thereof

Publication Date: 2025.11.18 SHENZHEN NEWSONIC TECH CO LTD

AI summary

A surface acoustic wave (SAW) device includes a substrate; an interdigital transducer (IDT) having lead-out portions and arrays of interdigital electrodes formed on the substrate, wherein the interdigital electrodes includes central portions, end portions, and intermediate portions between the end portions and the lead-out portions, and a thickness of the interdigital electrodes at the end portions is greater than a thickness of the interdigital electrodes at the central portions and the intermediate portions, thereby forming protruding structures at the end portions of the interdigital electrodes; a protective layer formed on the protruding structures at the end portions of the interdigital electrodes; a first temperature compensation layer formed on the protective layer; a second temperature compensation layer formed on the first temperature compensation layer and on the central portions and the intermediate portions of the interdigital electrodes; and a passivation layer formed on the second temperature compensation layer.