MEMS Microphone Electrode Stress Dispersion
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Solution Overview
Problem
MEMS microphones suffer from stress concentration issues in their vibration structures, leading to potential failure and affecting microphone performance.
Innovation Solution
The design incorporates a second electrode with shape separation gaps and stress dispersion structures, such as open holes or bent dispersion gaps, to decentralize stress and improve rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed structure is used for the capacitive system and connection with the substrate, then the structure is simple and easy to manufacture, but stress concentration occurs in the center position of the vibration structure under sound pressure, leading to potential failure
Solution Approach 1:
The second electrode is divided into multiple independent electrode sections through shape separation gaps. These gaps split the continuous electrode structure into segmented sections, allowing stress to be distributed across multiple regions rather than concentrated at the center, thereby improving vibration structure reliability while maintaining manufacturing feasibility
Solution Approach 2:
The electrode structure is designed with varying local properties: the shape separation gaps are positioned to create regions of different stress distribution characteristics. The end gaps extending toward edges and the splitting gap arrangement create localized stress relief zones where needed, optimizing the overall stress distribution across the vibration structure
2Reliability
If the second electrode is designed with shape separation gaps and stress dispersion structures, then stress concentration is reduced and reliability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The electrode is segmented into multiple sections using shape separation gaps that can be integrated into standard MEMS fabrication processes. The segmentation pattern (splitting gap in the middle, end gaps at edges) is designed to be compatible with photolithography and etching processes, reducing the impact on manufacturing complexity while achieving stress distribution
Solution Approach 2:
The end gaps are designed with smooth curved transitions instead of sharp angles, creating stress dispersion structures that naturally distribute stress. The curved geometry of the end gaps extending toward the edges provides stress relief while maintaining structural integrity and compatibility with standard fabrication techniques
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
This design effectively reduces stress concentration points, enhancing the stability and reliability of the MEMS microphone by distributing stress more evenly across the electrode.
Implementation Method 1
The vibrating structure vibrates under the action of sound waves, which in turn changes the capacitance of the capacitive system, thereby converting the sound wave signal into an electric signal
Data Source
AI summary
The present invention discloses a MEMS microphone, which includes a substrate with a back cavity, a connection part, and a capacitive system arranged in the connection part. The capacitive system includes a first electrode connected to the inner wall of connection part, and a second electrode disposed on the substrate near the first electrode and spaced from the first electrode. The second electrode has two shape separation gaps. The shape separation gap includes a splitting gap in the second electrode, and two end gaps. The second electrode is divided into an effective vibration area and an auxiliary area by adopting a cracking gap structure. While improving the sensitivity of the first electrode, the stress concentration point of the second electrode is directed to the edge of the second electrode, so as to disperse the stress under the action of loud pressure.