MEMS Membrane Laser Nanostructures for Liquid Repellency
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Solution Overview
Problem
MEMS devices, particularly microphones, face robustness and longevity issues due to environmental contamination from liquids, as they have hydrophilic surfaces that attract and retain contaminants, leading to corrosion and electrical failures.
Innovation Solution
A MEMS device with a liquid-repellent membrane surface featuring monolithically integrated nanostructures created by laser structuring, providing hydrophobic and oleophobic characteristics to prevent liquid adherence and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a planar membrane surface with hydrophilic characteristics is used, then the membrane can be easily manufactured with simple structure, but the membrane surface attracts and retains liquid contaminants leading to device failure
Solution Approach 1:
The patent transforms the membrane surface from a two-dimensional planar structure to a three-dimensional nanostructured surface by creating arrays of nanopillars, nanowalls, or other vertical nanostructures. This dimensional change provides liquid-repellent properties through geometric effects (lotus effect) while maintaining the membrane's functional integrity, thereby improving reliability without significantly complicating the manufacturing process
Solution Approach 2:
The patent modifies the surface parameters of the membrane by creating nanostructures with specific geometric parameters (height, diameter, spacing, aspect ratio) that optimize liquid repellency. By controlling these nanoscale parameters, the membrane achieves hydrophobic/oleophobic characteristics while retaining compatibility with standard MEMS fabrication processes
2Reliability
If external discrete environmental barrier components are added to protect the membrane, then liquid repellency is achieved, but the package size increases and production cost rises
Solution Approach 1:
The patent merges the protective environmental barrier function directly into the membrane structure itself by integrating nanostructures onto the membrane surface. This eliminates the need for separate external barrier components, thereby maintaining liquid protection while reducing package size and simplifying the overall device structure
Solution Approach 2:
The nanostructured membrane surface serves multiple functions simultaneously: it maintains the membrane's primary acoustic/transducer function while providing secondary protection against liquid contamination. This multi-functionality eliminates the need for additional dedicated protective components, reducing both package complexity and production cost
3Reliability
If external environmental barrier components are used, then membrane protection is provided, but acoustic performance deteriorates
Solution Approach 1:
By creating vertical nanostructures on the membrane surface rather than adding lateral barrier layers, the patent protects the membrane while maintaining its acoustic transparency. The nanoscale vertical structures repel liquids without significantly blocking acoustic wave transmission, thus preserving acoustic performance
4Reliability
If conventional manufacturing processes are used, then production is simple, but the membrane surface is susceptible to contamination from evaporated liquids
Solution Approach 1:
The patent applies liquid-repellent nanostructures to the membrane surface during the manufacturing process before the device is deployed. This preliminary structuring prevents contamination from occurring in the first place by repelling liquids at the surface level, eliminating the need for post-manufacturing protection or maintenance cleaning
Solution Approach 2:
The patent incorporates nanostructure formation into the existing MEMS manufacturing process by utilizing standard deposition, etching, and lithography techniques with modified parameters. This approach creates contamination-resistant surfaces using conventional manufacturing equipment and processes, avoiding the need for specialized or complex additional manufacturing steps
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 nanostructured membrane surface effectively repels liquids and contaminants, enhancing the robustness and longevity of MEMS devices by preventing corrosion and electrical failures, and potentially offering self-cleaning properties.
Implementation Method 1
the nanostructures are created by applying a laser structuring process
Implementation Method 2
the nanostructures provide a membrane surface with a hydrophobic and/or oleophobic characteristic
Implementation Method 3
droplets of water or other liquids tend to adsorb onto the membrane surface
Data Source
AI summary
In accordance with an embodiment, a method producing a microelectromechanical system (MEMS) device includes: providing a substrate comprising a first substrate surface and an opposite second substrate surface, wherein the substrate comprises a sacrificial layer arranged at the first substrate surface; depositing a membrane material layer onto the sacrificial layer; the membrane material layer forms a free-standing membrane structure covering the cavity; and creating nanostructures in at least one of a first membrane surface or an opposite second membrane surface of the membrane material layer, wherein the nanostructures protrude from the respective membrane surface of the membrane material layer, and the nanostructures are created by applying a laser structuring process.