MEMS Packaging with Release Aperture and Cap
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Solution Overview
Problem
Current wafer level packaging technologies face challenges such as incompatibility with device fabrication processes, area/density penalties, contamination issues, and structural weaknesses, particularly in the integration of MEMS devices.
Innovation Solution
A method for fabricating MEMS devices involves forming a MEMS structure and a release aperture at the same level above a first sacrificial layer, followed by the formation of a second sacrificial layer and a cap, where the second sacrificial layer is removed through the release aperture, and the aperture is plugged to create a structurally strong and contamination-resistant package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wafer level packaging is used to protect the device and provide interconnections, then packaging functionality is improved, but structural strength deteriorates
Solution Approach 1:
The packaging structure is segmented into multiple functional layers: a support layer providing mechanical strength, a release aperture layer enabling sacrificial material removal, and a cap layer providing protection. This segmentation allows each layer to optimize its specific function without compromising overall structural integrity.
Solution Approach 2:
The packaging employs composite material construction with the support layer made from structurally strong materials and the cap layer providing environmental protection. The combination of different materials with complementary properties resolves the contradiction between packaging functionality and structural strength.
2Manufacturing precision
If release aperture is formed to remove sacrificial material, then manufacturing precision is improved, but contamination risk increases
Solution Approach 1:
A cap layer is introduced as an intermediary component that seals the release aperture after sacrificial material removal. This cap acts as a barrier preventing environmental contamination from entering through the aperture, thus resolving the contradiction between achieving precise release and preventing contamination.
Solution Approach 2:
The sacrificial material removal through the release aperture is performed as a preliminary action before final packaging sealing. By completing the release operation first and then sealing with the cap, the process achieves manufacturing precision while subsequently eliminating the contamination pathway.
3Reliability
If complicated packaging schemes are used to protect MEMS devices, then device protection is improved, but device complexity increases
Solution Approach 1:
The support layer serves multiple functions simultaneously: it provides mechanical strength, supports the release aperture structure, and enables subsequent cap attachment. This multi-functionality reduces the need for additional separate components, thereby simplifying the overall packaging scheme while maintaining comprehensive device protection.
Solution Approach 2:
The packaging structure merges the support function, release aperture function, and protective cap function into an integrated multi-layer assembly. By combining these functions into a unified structure rather than separate components, the packaging scheme achieves effective device protection with reduced complexity.
Data Source
AI summary
The present disclosure provides a micro-electro-mechanical systems (MEMS) device. In an embodiment, a device includes a substrate; a MEMS structure disposed above a sacrificial layer opening above the substrate; a release aperture disposed at substantially a same level above the sacrificial layer opening as the MEMS structure; a first cap over the MEMS structure and the sacrificial layer opening, a leg of the first cap disposed between the MEMS structure and the release aperture; and a second cap plugging the release aperture.