MEMS Movable Element Roughness for Anti-Stiction Layer Quality
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Solution Overview
Problem
Microelectromechanical systems (MEMS) devices, such as accelerometers and gyroscopes, face stiction issues due to the minimal surface area contact between flat surfaces, leading to poor anti-stiction layer quality and reduced sensitivity and lifespan.
Innovation Solution
Introducing roughness on the movable element's surface within the MEMS package, which increases the surface area for the anti-stiction layer formation, thereby enhancing the layer's quality and reducing stiction, without additional masks or affecting bond interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If flat surfaces are used for the movable element, then the manufacturing process is simple, but the anti-stiction layer quality is poor due to minimal surface area contact
Solution Approach 1:
The patent transitions from a flat two-dimensional surface to a rough three-dimensional surface structure. The rough surface includes peaks and valleys that increase the effective surface area by a factor of 2-10 times, providing better contact area for the anti-stiction layer formation while maintaining the same planar footprint.
Solution Approach 2:
The rough surface structure is applied locally to the movable element's contact surfaces where anti-stiction is most critical. The roughness is created through selective processes that affect only the surfaces requiring enhanced anti-stiction properties, while other areas remain relatively smooth.
2Manufacturing precision
If roughness is introduced on the movable element surface, then the surface area for anti-stiction layer formation increases, but the manufacturing process becomes more complex
Solution Approach 1:
The rough surface is formed during the manufacturing process before the anti-stiction layer deposition. By pre-creating the rough surface structure through processes like chemical mechanical polishing or etching, the subsequent anti-stiction layer formation benefits from increased surface area without requiring additional complex processing steps.
Solution Approach 2:
The patent changes the surface topology parameter from flat to rough, which fundamentally alters the surface area available for anti-stiction layer formation. This parameter change is achieved through controlled manufacturing processes that create peaks and valleys, increasing the effective contact area by 2-10 times.
3Reliability
If flat surfaces are used, then the device structure is simple, but stiction occurs more easily reducing device lifespan
Solution Approach 1:
The patent introduces surface roughness that creates peaks and valleys, increasing the effective surface area by 2-10 times. This dimensional change from flat to rough surface provides better mechanical interlocking and increased contact area for the anti-stiction layer, preventing stiction and extending device lifespan.
Solution Approach 2:
The patent converts the potential harm of increased surface complexity into a benefit by using the rough surface structure to enhance anti-stiction properties. The peaks and valleys, while increasing structural complexity, create better mechanical interlocking and increased contact area that prevents stiction, thereby extending device lifespan.
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
The roughness minimizes stiction and improves the uniformity and quality of the anti-stiction layer, extending the lifespan and sensitivity of MEMS devices.
Implementation Method 1
Introducing roughness on the movable element's surface within the MEMS package, which increases the surface area for the anti-stiction layer formation
Data Source
AI summary
A microelectromechanical systems (MEMS) package with roughness for high quality anti-stiction is provided. A device substrate is arranged over a support device. The device substrate comprises a movable element with a lower surface that is rough and that is arranged within a cavity. A dielectric layer is arranged between the support device and the device substrate. The dielectric layer laterally encloses the cavity. An anti-stiction layer lines the lower surface of the movable element. A method for manufacturing the MEMS package is also provided.