Thin-Film Microshell Encapsulation for MEMS Vacuum Integrity

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Solution Overview

Problem

Conventional thin-film encapsulation methods for microelectromechanical systems (MEMS) face challenges in maintaining vacuum integrity and robustness against high-pressure packaging processes, and integrating diverse device functionalities within a single process flow.

Innovation Solution

The development of a process flow for thin-film microshell structures that allows for the co-integration of MEMS devices, including sensors and actuators, by forming a vacuum cavity with a smaller volume than conventional wafer-bonded cavities while maintaining equivalent vacuum levels, and incorporating optional processing modules for structural reinforcement and functional decoupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If conventional wafer-bonded cavity structures are used, then larger volume vacuum cavities can be formed, but the vacuum integrity and robustness against high-pressure packaging processes deteriorate

Engineering Contradiction:

Improvevacuum cavity volumeVSAvoidvacuum integrity under high pressure

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The cavity structure is segmented into a thin-film microshell enclosure that separates the vacuum cavity from the bulk substrate. This segmentation allows the cavity to be isolated and protected from external high-pressure packaging processes while maintaining vacuum integrity, resolving the contradiction between cavity volume and vacuum robustness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The microshell structure employs composite thin-film materials with varying mechanical properties - including structural layers for strength and functional layers for specific性能的. This composite approach enables the cavity to maintain vacuum integrity under high pressure while achieving the desired volume, resolving the contradiction between reliability and volume.

Inventive Principle:

Principle #40Composite materials

2Reliability

If thin-film microshell structures are used, then vacuum integrity and robustness against high-pressure packaging are improved, but the cavity volume is reduced

Engineering Contradiction:

Improvevacuum integrity under high pressureVSAvoidvacuum cavity volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The invention optimizes parameters including thin-film thickness, material composition, and microshell geometry to achieve the maximum possible cavity volume while maintaining vacuum integrity under high pressure. By carefully controlling these parameters, the design resolves the contradiction between small volume and high reliability.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If conventional encapsulation processes are used, then device fabrication is simpler, but compatibility with thermal budget constraints and post-processing steps is reduced

Engineering Contradiction:

Improveprocess simplicityVSAvoidthermal budget compatibility

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The microshell structure is formed as part of the device fabrication process itself, with the encapsulation layers being deposited concurrently with other device structures. This preliminary action eliminates the need for separate high-temperature bonding steps, maintaining process simplicity while ensuring thermal budget compatibility with subsequent post-processing steps.

Inventive Principle:

Principle #10Preliminary action

4Adaptability or versatility

If diverse device functionalities are integrated, then device versatility is improved, but process flow complexity increases

Engineering Contradiction:

Improvedevice functionality integrationVSAvoidprocess flow complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The thin-film microshell process flow is designed as a universal platform that can accommodate diverse device functionalities including sensors, actuators, and other MEMS devices. By using the same basic encapsulation process for different device types, the invention achieves multi-functionality without proportionally increasing process complexity, resolving the contradiction between versatility and process simplicity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10173893B2Methods and structures for thin-film encapsulation and co-integration of same with microelectronic devices and microelectromechanical systems (MEMS)

Publication Date: 2019.01.08 SEMICON MFG INT (SHANGHAI) CORP

AI summary

Methods and structures that may be implemented in one example to co-integrate processes for thin-film encapsulation and formation of microelectronic devices and microelectromechanical systems (MEMS) such as sensors and actuators. For example, structures having varying characteristics may be fabricated using the same basic process flow by selecting among different process options or modules for use with the basic process flow in order to create the desired structure/s. Various process flow sequences as well as a variety of device design structures may be advantageously enabled by the various disclosed process flow sequences.