Compact MEMS Package with Surface-Conformal Dielectric Coating

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Solution Overview

Problem

Existing MEMS transducer packages are bulky due to metal covers, which hinder compact design and acoustic performance, and alternative packaging methods like metallized polymer films are complex and stressful for the components.

Innovation Solution

A surface-conform dielectric coating with a polymer layer applied via spray, mist, or vapor coating, followed by an electrically conductive layer, providing a compact and hermetic protection without the need for a rigid cover, allowing targeted removal in interaction areas to maintain acoustic properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal covers are used for MEMS transducer packaging, then protection against dust, moisture, and ESD is improved, but package size increases and acoustic properties deteriorate

Engineering Contradiction:
Improveprotection against dust, moisture, and ESDVSAvoidpackage size
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent replaces rigid metal covers with thin-film dielectric layers (such as parylene, silicon oxide, or silicon nitride) deposited directly onto the MEMS transducer components. These thin films provide hermetic sealing and protection against moisture, dust, and ESD while maintaining a compact package footprint and preserving acoustic properties by eliminating the need for large metal enclosures.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs composite packaging structures combining multiple dielectric layers with different properties. For example, a multi-layer dielectric system may include adhesive layers, barrier layers, and protective layers, each contributing specific functions such as hermetic sealing, mechanical support, or ESD protection, thereby achieving comprehensive protection without increasing package size.

Inventive Principle:
Principle #40Composite materials

2Reliability

If metal covers are used for MEMS transducer packaging, then protection against dust, moisture, and ESD is improved, but acoustic properties deteriorate

Engineering Contradiction:
Improveprotection against dust, moisture, and ESDVSAvoidacoustic properties
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Thin-film dielectric coatings provide effective protection against environmental contaminants while being acoustically transparent or minimally intrusive. The thinness and material composition of these dielectric layers allow sound waves to pass through with minimal attenuation or distortion, preserving the acoustic performance of the MEMS transducer.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent applies dielectric protection selectively to specific areas of the MEMS transducer that require protection, while leaving acoustic interaction regions exposed or minimally coated. This localized approach ensures that protection is provided where needed without interfering with the acoustic function of the transducer.

Inventive Principle:
Principle #3Local quality

3Volume of moving object

If metallized polymer films are used for packaging, then compact design is achieved, but manufacturing complexity increases and component stress increases

Engineering Contradiction:
Improvepackage sizeVSAvoidmanufacturing complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent replaces mechanical packaging operations (such as film lamination, metalizing, and laser drilling) with vapor-phase dielectric deposition processes. These deposition methods directly form protective layers on the MEMS components without requiring mechanical handling or post-processing steps, thereby simplifying manufacturing and reducing component stress.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent eliminates the metallization step entirely by using pure dielectric materials deposited via vapor-phase processes. This extraction of the metalizing operation removes a complex and stress-inducing manufacturing step while maintaining the compact package design through direct thin-film formation.

Inventive Principle:
Principle #2Taking out (Extraction)

4Volume of moving object

If metallized polymer films are used for packaging, then compact design is achieved, but manufacturing complexity increases

Engineering Contradiction:
Improvepackage sizeVSAvoidmanufacturing process simplicity
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent replaces complex mechanical packaging operations with vapor-phase dielectric deposition, which is a mature, well-established semiconductor manufacturing process. This substitution eliminates multiple manufacturing steps including film lamination, metal vapor deposition, and laser drilling, thereby simplifying the overall manufacturing process while maintaining compact package dimensions.

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 results in a highly compact, cost-effective MEMS package that protects against dust, moisture, and ESD while preserving acoustic properties and simplifying manufacturing, enabling direct contact between the MEMS membrane and the environment without compromising protection.

Implementation Method 1

surface-conformal coating of the MEMS element with a dielectric layer is carried out, for example by spray coating, mist coating, and/or vapor coating

Methodology Applied
Scientific EffectSpray coating: Spray

Implementation Method 2

surface-conformal coating of the MEMS element with a dielectric layer is carried out, for example by spray coating, mist coating, and/or vapor coating

Methodology Applied
Scientific EffectVapor coating: Physical Vapour Deposition

Implementation Method 3

an electrically conductive layer is preferably applied by means of physical or chemical vapor deposition

Methodology Applied
Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 4

The package preferably serves as a housing for the MEMS element... protecting the component from dust, moisture, and liquids, as well as from ESD (electrostatic discharge)

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Data Source

PatentEP4178905B1Compact MEMS package which is easy to manufacture having improved protection properties
Publication Date: 2024.08.28 HAHN SCHICKARD GESELLSCHAFT FUR ANGEWANDTE FORSCHUNG EV
  • EP4178905B1 patent drawingFigure 1~3
  • EP4178905B1 patent drawingFigure 4~5
  • EP4178905B1 patent drawing

AI summary

The invention relates preferably to a MEMS package with at least one layer for protecting a MEMS element, wherein the MEMS element has at least one MEMS interaction region on a substrate, and a surface-conformal coating of the MEMS element with a dielectric layer takes place. The invention relates particularly preferably to a MEMS transducer package in which there is a MEMS element, for example with a MEMS membrane and processor, preferably an integrated circuit, arranged on a substrate. To provide protection, preferably first a surface-conformal coating of a dielectric onto the MEMS element takes place, for example by spray coating, mist coating and/or vapour coating. Then preferably an electrically conducting layer is applied. Depending on the configuration, the layers can be removed in regions above a MEMS interaction region of the MEMS element, for example for a sound opening in a MEMS membrane.