MEMS Transducer Substrate Recesses for Stiction Reduction
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Solution Overview
Problem
MEMS transducers, particularly capacitive microphones, face issues with membrane damage and stiction due to high pressure impulses, leading to performance degradation or failure, especially when subjected to mechanical shocks like device drops.
Innovation Solution
The design incorporates a substrate with recesses on its upper surface between the edge of the cavity and the membrane perimeter, reducing the contact area and adhesive forces, thereby minimizing the risk of stiction and membrane damage during high-pressure events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the membrane is provided with a large overlap region on the substrate, then the membrane is well-supported and stable, but the adhesive forces increase leading to stiction and membrane damage during high-pressure events
Solution Approach 1:
The overlap region is segmented into multiple discrete support structures (ridges or posts) rather than a continuous large contact area. This segmentation reduces the total adhesive contact area while maintaining mechanical support, thereby reducing stiction forces during high-pressure events while preserving membrane stability.
Solution Approach 2:
The support structures are strategically positioned at specific locations within the overlap region where they provide necessary mechanical support while minimizing contact area. This local optimization allows the membrane to be supported where needed while reducing adhesive forces in critical areas prone to stiction.
2Strength
If the contact area between membrane and substrate is increased, then the membrane support is improved, but the adhesive forces increase causing stiction during high-pressure impulses
Solution Approach 1:
The continuous contact area is divided into discrete support structures (ridges or posts) that provide mechanical support strength while minimizing the total surface area in contact with the membrane. This segmentation reduces adhesive forces and stiction risk while maintaining the necessary support strength.
Solution Approach 2:
The membrane is designed as a thin flexible structure that can deflect and adapt to the discrete support structures. This flexibility allows the membrane to maintain contact with support points for mechanical strength while the limited contact area reduces adhesive forces, preventing stiction during pressure variations.
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 configuration effectively reduces the likelihood of membrane adherence to the substrate and mitigates damage from high-pressure impulses, enhancing the robustness and reliability of MEMS transducers.
Implementation Method 1
reducing the contact area and adhesive forces, thereby minimizing the risk of stiction and membrane damage
Data Source
AI summary
The application describes a MEMS transducer comprising a substrate having a cavity. The transducer exhibits a membrane layer supported relative to the substrate to define a flexible membrane. An upper surface of the substrate comprises an overlap region between the edge of the cavity and a perimeter of the flexible membrane where the membrane overlies the upper surface of the substrate. At least one portion of the overlap region of the upper surface of the substrate is provided with a plurality of recesses. The recesses are defined so as to extend from the edge of the cavity towards the perimeter of the flexible membrane.