MEMS Outgassing Prevention Structure and Gas Getter
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Solution Overview
Problem
In micro-electro mechanical system (MEMS) package systems, gases outgassing from dielectric materials can affect the operation of MEMS devices by changing the ambient environment, leading to operational issues.
Innovation Solution
Incorporating an outgassing prevention structure, such as a layer of silicon nitride or silicon oxynitride, to reduce gas permeability and prevent gases like oxygen and carbon dioxide from escaping, combined with a gas getter structure that absorbs excess gases, maintaining a stable environment for the MEMS device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dielectric materials are used in MEMS package systems, then the device structure is formed and electrical insulation is provided, but gases outgas from the dielectric materials into the sealed space, affecting MEMS device operation
Solution Approach 1:
A barrier layer is introduced as an intermediary between the dielectric material and the sealed space. This barrier layer selectively blocks gas molecules from migrating through the dielectric material into the sealed cavity, while maintaining electrical insulation and structural integrity. The barrier layer acts as a mediator that prevents the harmful interaction between outgassing dielectric materials and the MEMS device environment.
Solution Approach 2:
The package structure employs composite materials by combining dielectric materials with a barrier layer having different gas permeability properties. This composite structure leverages the electrical insulation properties of the dielectric material while utilizing the gas-blocking properties of the barrier layer, creating a multi-functional package structure that addresses both electrical and environmental requirements.
2Reliability
If the sealed space is vacuumed to improve MEMS device operation, then the ambient environment is optimized, but gases can still permeate through dielectric materials into the space over time
Solution Approach 1:
The barrier layer is incorporated into the package structure before sealing, creating a pre-established gas blocking pathway. This preliminary protective measure ensures that even before vacuuming occurs, the barrier layer is in place to prevent gas permeation, thereby maintaining long-term environmental stability without requiring repeated vacuuming or environmental adjustments.
Solution Approach 2:
The barrier layer serves as a permanent intermediary that continuously prevents gas molecules from penetrating through the dielectric material into the sealed space. This mediator maintains the vacuum environment stability over extended periods by blocking the permeation pathway, eliminating the need for frequent environmental reconditioning.
3Reliability
If thicker dielectric layers are used to improve electrical insulation, then electrical performance is enhanced, but the amount of outgassing material increases, worsening the gas contamination problem
Solution Approach 1:
The dielectric structure is segmented by introducing a thin barrier layer within or adjacent to the dielectric material. This segmentation creates distinct functional zones: the dielectric material provides electrical insulation while the barrier layer provides gas blocking. This allows the use of thicker dielectric layers for improved electrical insulation without proportionally increasing outgassing, as the barrier layer intercepts gas molecules before they can migrate into the sealed space.
Solution Approach 2:
The barrier layer acts as a mediator that decouples the relationship between dielectric thickness and outgassing volume. By inserting this intermediate gas-blocking layer, the system can utilize thicker dielectric materials for enhanced electrical insulation while the barrier layer prevents the corresponding increase in outgassing material from contaminating the sealed environment.
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 outgassing prevention structure effectively maintains a stable ambient around the MEMS device, reducing operational interference and ensuring consistent performance, while the gas getter structure further minimizes gas presence, enhancing the reliability and accuracy of MEMS devices.
Implementation Method 1
Incorporating an outgassing prevention structure, such as a layer of silicon nitride or silicon oxynitride, to reduce gas permeability and prevent gases like oxygen and carbon dioxide from escaping
Implementation Method 2
combined with a gas getter structure that absorbs excess gases, maintaining a stable environment for the MEMS device
Data Source
AI summary
A device includes a capping substrate bonded with a substrate structure. The substrate structure includes an integrated circuit structure. The integrated circuit structure includes a top metallic layer disposed on an outgasing prevention structure. At least one micro-electro mechanical system (MEMS) device is disposed over the top metallic layer and the outgasing prevention structure.