MEMS Package Structure with Dual Cavity Pressure Equalization
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Solution Overview
Problem
The packaging process of Micro Electro-Mechanical Systems (MEMS) components is critical for preventing external contaminants, but existing methods can be costly and may not effectively seal the devices, leading to performance degradation due to differential pressure when moving from vacuum to atmospheric environments.
Innovation Solution
A MEMS package structure is designed with a substrate, interconnecting structure, upper metallic layers, deposition elements, and packaging elements, where the structure is sealed in a way that maintains communication between cavities to prevent collapse under pressure changes, and can be fabricated at low temperatures to avoid damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MEMS structure is sealed in the vacuum environment, then the hermetic sealing is improved, but the layers above the MEMS region collapse due to differential pressure
Solution Approach 1:
The sealing process is divided into two distinct stages: first sealing the MEMS structure in vacuum environment, then maintaining a non-gastight channel above the interconnecting structure. This segmentation allows the lower portion to be hermetically sealed while the upper portion remains open to equalize pressure, preventing collapse of the layers above the MEMS region.
Solution Approach 2:
The non-gastight channel acts as an intermediary element between the vacuum-sealed MEMS region and the atmospheric pressure environment above. This intermediate structure allows pressure equalization for the upper layers while maintaining vacuum sealing for the MEMS components, resolving the contradiction between hermetic sealing and structural integrity.
2Reliability
If high temperature process is used for packaging, then the sealing effectiveness is improved, but the MEMS package structure is damaged
Solution Approach 1:
The patent changes the temperature parameter from high temperature to low temperature for the packaging process. By performing the sealing operations at low temperatures, the method achieves effective hermetic sealing without causing thermal damage to the MEMS package structure, thus resolving the contradiction between sealing effectiveness and structural integrity.
3Ease of manufacture
If the packaging process is simplified, then the production cost is reduced, but the sealing effectiveness is compromised
Solution Approach 1:
The patent performs preliminary sealing of the MEMS structure in the vacuum environment before final packaging, ensuring hermetic sealing is achieved during the vacuum process itself. This preliminary action eliminates the need for additional high-temperature sealing steps, thereby maintaining sealing effectiveness while simplifying the overall packaging process and reducing production costs.
Data Source
AI summary
A MEMS package structure, including a substrate, an interconnecting structure, an upper metallic layer, a deposition element and a packaging element is provided. The interconnecting structure is disposed on the substrate. The MEMS structure is disposed on the substrate and within a first cavity. The upper metallic layer is disposed above the MEMS structure and the interconnecting structure, so as to form a second cavity located between the upper metallic layer and the interconnecting structure and communicates with the first cavity. The upper metallic layer has at least a first opening located above the interconnecting structure and at least a second opening located above the MEMS structure. Area of the first opening is greater than that of the second opening. The deposition element is disposed above the upper metallic layer to seal the second opening. The packaging element is disposed above the upper metallic layer to seal the first opening.