Etch-Stop Protection Layer for Integrated Acoustic Capacitors

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Solution Overview

Problem

As the number of frequency bands in wireless communication increases, existing acoustic filters face challenges in reducing intermodulation distortion and maintaining performance, particularly in portable devices where size constraints are significant, and the use of capacitive elements for filtering introduces power loss and area consumption issues.

Innovation Solution

The integration of a capacitive element with an acoustic device on a substrate, where a protective layer acts as an etch stop during the formation of a dielectric region, allowing for the reduction of intermodulation distortion and preventing damage to the acoustic device during etching processes, thereby enhancing filter performance and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If capacitive elements are used for filtering in acoustic filters, then filtering performance is improved, but power loss and area consumption increase

Engineering Contradiction:

Improvefiltering performanceVSAvoidpower loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent combines capacitive elements with acoustic devices into an integrated structure where the capacitive element is formed directly over the acoustic device substrate. This merging allows the capacitive filtering function to be integrated with the acoustic filtering function, improving overall filtering performance while sharing the same physical space, thereby mitigating area consumption increases.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If capacitive elements are integrated with acoustic devices, then intermodulation distortion is reduced, but device complexity increases

Engineering Contradiction:

Improveintermodulation distortion reductionVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the device into distinct functional regions: an acoustic device region and a capacitive element region. The capacitive element is formed over a second region of the substrate adjacent to the acoustic device, allowing independent optimization of each component while maintaining their integrative benefit for reducing intermodulation distortion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a protective layer as an intermediary between the capacitive element and the acoustic device. This protective layer prevents damage to the acoustic device during etching processes while allowing the capacitive element to function, thus enabling the integration without proportionally increasing device complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If protective layer is used during capacitive element formation, then acoustic device is protected from damage, but manufacturing steps increase

Engineering Contradiction:

Improveacoustic device protectionVSAvoidmanufacturing steps

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The protective layer is formed preliminarily before the capacitive element is fully fabricated. This preliminary action protects the acoustic device from damage during subsequent etching processes while allowing the capacitive element formation to proceed. The protective layer is strategically placed only where needed, balancing protection with manufacturing efficiency.

Inventive Principle:

Principle #10Preliminary action

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 approach reduces intermodulation distortion and improves the overall performance of acoustic filters by protecting the acoustic device during capacitive element formation, leading to more efficient signal processing and reduced power loss in wireless communication devices.

Implementation Method 1

a protective layer acts as an etch stop during the formation of a dielectric region

Methodology Applied

Scientific EffectEtch stop:

Implementation Method 2

The protective layer may be removed (e.g., using a wet chemical etch process) after the dielectric region's etching is complete

Methodology Applied

Scientific EffectSelective etching:

Implementation Method 3

Using a piezoelectric material as a vibrating medium, acoustic resonators operate by transforming an electrical signal wave propagating along an electrical conductor into an acoustic wave that is propagating via the piezoelectric material

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12047744B2Etch stop and protection layer for capacitor processing in electroacoustic devices

Publication Date: 2024.07.23 RF360 SINGAPORE PTE LTD

AI summary

Electroacoustic devices with a capacitive element and methods for fabricating such electroacoustic devices. An example method includes forming an acoustic device above a first region of a substrate, and forming a capacitive element above a second region of the substrate and adjacent to the acoustic device. The forming of the capacitive element may include forming a protective layer above the substrate where a first portion of the protective layer is above the second region of the substrate and a second portion of the protective layer is above the first region of the substrate, forming a dielectric region above the protective layer, and forming an electrode above the dielectric region. The dielectric region may include a different material than the protective layer.