MEMS Sensor Stress Decoupling via Nested Substrate Cavities
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Solution Overview
Problem
Current methods for producing MEMS sensors, such as pressure sensors and microphones, face challenges in effectively decoupling regions of the substrate to manage mechanical stress, which affects the performance and reliability of the sensors.
Innovation Solution
A method involving the production of a substrate with a decoupling structure and multiple etching processes to create cavities that encompass the MEMS structure, allowing for stress decoupling between regions, enhancing the mechanical integrity and functionality of the sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a decoupling structure with recesses is produced in the substrate to decouple stress between regions, then the mechanical integrity and reliability of the MEMS sensor is improved, but the device complexity and manufacturing steps increase
Solution Approach 1:
The substrate is segmented into multiple regions through the decoupling structure with recesses, separating the MEMS structure region from other substrate regions. This segmentation allows independent stress management in different areas, improving mechanical integrity while maintaining overall structural functionality.
Solution Approach 2:
The decoupling structure utilizes the vertical dimension by creating recesses (cavities) within the substrate thickness, rather than only horizontal partitions. This vertical segmentation approach effectively decouples stress between regions while minimizing lateral space consumption and reducing overall structural complexity.
2Reliability
If multiple etching processes are used to produce cavities that encompass the MEMS structure, then stress decoupling and free vibration are enhanced, but the manufacturing time and process complexity increase
Solution Approach 1:
The cavities are produced using multiple etching processes where the first cavity is etched before the second cavity, with each etching process building upon the previous one. This preliminary action approach allows systematic stress decoupling to be achieved through sequential cavity formation, ensuring proper mechanical isolation before final assembly.
Solution Approach 2:
The cavities are nested within each other, with the second cavity encompassing the first cavity. This nested structure allows multiple etching processes to create a hierarchical cavity system that efficiently decouples stress across different regions while optimizing the use of manufacturing steps and reducing overall process complexity.
3Reliability
If the second cavity encompasses the first cavity and adjoins base regions of both MEMS and decoupling structures, then stress management is optimized, but the manufacturing precision requirements increase
Solution Approach 1:
The decoupling structure features local quality variations through recesses at specific locations within the substrate. These localized recesses are positioned to optimally decouple stress between the MEMS structure region and other regions, allowing effective stress management without requiring high precision across the entire substrate, thus reducing overall manufacturing precision requirements.
Data Source
AI summary
In accordance with an embodiment, a MEMS structure is produced on a front side of a substrate. A decoupling structure which has recesses is produced in the substrate, which decoupling structure decouples a first region from a second region of the substrate in terms of stresses. In a rear side, situated opposite the front side, of the substrate, a first cavity is produced by means of a first etching process and a second cavity is produced by means of a second etching process. The first cavity and the second cavity are produced such that the second cavity encompasses the first cavity and such that the second cavity adjoins a base region of the MEMS structure and a base region of the decoupling structure.