Hermetic MEMS Package with Integrated CMOS Substrate
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Solution Overview
Problem
Conventional hermetic MEMS devices face high costs, production yield issues, and parasitic effects due to the conjunction of MEMS and sensing ICs, which are manufactured in separate substrates, leading to noise interference and performance limitations.
Innovation Solution
A hermetic MEMS package is designed with a CMOS MEMS chip featuring a structural dielectric layer for electrical interconnection and protection, where the MEMS structure is exposed in a chamber formed on one side of the substrate, and an additional substrate is adhered to seal the chamber, eliminating the need for a CMOS circuit on the second substrate, thus integrating IC and MEMS for high performance and reducing parasitic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS structure and sensing circuits are manufactured in separate substrates, then hermetic packaging can be achieved, but device complexity and production cost increase
Solution Approach 1:
The patent merges the MEMS structure and sensing circuits into a single integrated substrate, eliminating the need for separate substrates and complex hermetic packaging. The sensing circuits are directly fabricated on the same substrate as the MEMS structure, reducing assembly steps and potential leakage points while maintaining hermetic sealing integrity.
Solution Approach 2:
The single substrate serves multiple functions simultaneously: it acts as the structural base for MEMS, the fabrication platform for sensing circuits, and the hermetic enclosure. This multi-functional design eliminates the need for separate packaging substrates and reduces overall device complexity.
2Ease of manufacture
If MEMS structure and sensing circuits are manufactured in separate substrates, then functional separation is achieved, but production yield decreases
Solution Approach 1:
By combining MEMS and sensing circuits fabrication into a single substrate process, the patent enables simultaneous manufacturing of both components with one set of fabrication steps, eliminating the need for separate substrate processing, alignment, and assembly operations that reduce yield.
3Manufacturing precision
If MEMS structure and sensing circuits are manufactured in separate substrates, then independent optimization is possible, but parasitic effects increase
Solution Approach 1:
The integration of sensing circuits directly on the MEMS substrate eliminates parasitic effects from inter-substrate connections. The sensing circuits are electrically connected to MEMS structures through on-substrate conductors, removing interface parasitics from separate substrate junctions and adhesive layers.
Data Source
AI summary
A hermetic microelectromechanical system (MEMS) package includes a CMOS MEMS chip and a second substrate. The CMOS MEMS Chip has a first substrate, a structural dielectric layer, a CMOS circuit and a MEMS structure. The structural dielectric layer is disposed on a first side of the first structural substrate. The structural dielectric layer has an interconnect structure for electrical interconnection and also has a protection structure layer. The first structural substrate has at least a hole. The hole is under the protection structure layer to form at least a chamber. The chamber is exposed to the environment in the second side of the first structural substrate. The chamber also comprises a MEMS structure. The second substrate is adhered to a second side of the first substrate over the chamber to form a hermetic space and the MEMS structure is within the space.