Double-Membrane MEMS Component for Contaminant Protection
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Solution Overview
Problem
Acoustic MEMS sensors, such as MEMS microphones, are vulnerable to contaminants and environmental factors like moisture, leading to malfunctions and requiring costly protection measures that can restrict product design and impair acoustic performance.
Innovation Solution
A double-membrane MEMS component production method involving a layer arrangement with sacrificial material between membrane structures, where anisotropic etching forms mechanical connection elements that are decoupled from the counterelectrode structure, providing mechanical protection and maintaining acoustic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical protection elements such as grilles are used to protect MEMS sensors from contaminants, then the sensors are protected against contaminants and moisture, but the product design is restricted and acoustic performance is impaired
Solution Approach 1:
The patent implements a double-membrane structure where the first membrane structure is nested within the second membrane structure, creating a protected internal space. The first membrane structure (inner membrane) is positioned inside the second membrane structure (outer membrane), forming a nested configuration that protects the sensitive sensor region while maintaining design flexibility and acoustic performance.
Solution Approach 2:
The patent uses flexible membrane structures instead of rigid grilles or protective housings. The first and second membrane structures are thin, flexible films that provide contaminant protection while allowing acoustic wave transmission. These flexible membranes can deflect in response to acoustic pressure while maintaining protection, unlike rigid grilles that restrict design and impair acoustics.
2Reliability
If mechanical protection elements such as grilles are used to protect MEMS sensors from contaminants, then the sensors are protected against moisture and particles, but acoustic behavior is impaired and SNR decreases
Solution Approach 1:
The nested double-membrane structure creates an internal protected space while maintaining acoustic coupling. The first membrane structure nests within the second, forming a configuration that protects the sensor region from moisture and particles while allowing acoustic waves to transmit through both membranes, preserving signal quality and SNR.
Solution Approach 2:
The flexible membrane structures serve as protective barriers that are acoustically transparent. These thin films allow acoustic wave transmission while providing moisture protection, unlike rigid grilles that scatter and block acoustic waves, thereby maintaining high signal-to-noise ratio and measurement precision.
3Reliability
If the capacitive structure uses a perforated back plate with a deflectable membrane, then the sensor capacitance is protected by the membrane, but the microphone design must be adapted depending on housing design and positioning
Solution Approach 1:
The nested double-membrane structure provides inherent protection for the sensor capacitance region regardless of housing configuration. The first membrane structure nests within the second, creating a self-contained protected space that maintains its protective function across different microphone housing designs and positioning orientations, eliminating the need for design adaptations.
Solution Approach 2:
The double-membrane structure serves multiple functions universally: it protects the sensor capacitance, maintains acoustic performance, and provides mechanical stability regardless of housing design. This universal protective structure eliminates the need to adapt the microphone design for different housing configurations or positioning requirements.
4Ease of manufacture
If MEMS sensors are left unprotected during component assembly, then the production process is simpler, but contaminations cause malfunctions and reduce production yield
Solution Approach 1:
The first membrane structure is formed as a preliminary protective barrier during the manufacturing process, before final assembly steps. This preliminary membrane structure protects the sensor region from contaminants during assembly operations, preventing malfunctions and maintaining high production yield without requiring complex clean room arrangements or additional protective measures.
Solution Approach 2:
The flexible membrane structure serves as an inherent protective barrier that is integrated into the sensor device itself. This thin film protection eliminates the need for external protective housings or complex assembly procedures, maintaining ease of manufacture while preventing contaminant ingress and ensuring high production yield.
5Device complexity
If a single membrane structure is used, then the design is simpler, but mechanical protection and stability are insufficient
Solution Approach 1:
The nested double-membrane structure provides enhanced mechanical protection through the first membrane structure nested within the second. This nested configuration creates multiple protective barriers that strengthen the overall structure and protect the sensor region more effectively than a single membrane, while adding only moderate complexity to the design.
Solution Approach 2:
The double-membrane structure functions as a composite protective system where two membrane structures work together to provide enhanced mechanical strength and protection. This composite configuration offers superior mechanical protection compared to a single membrane structure, while the membranes are integrated into a unified design that does not excessively increase overall complexity.
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 approach enhances mechanical protection and stability while improving electrical signal behavior, including SNR and THD, allowing for differential read-out and reduced exposure to contaminants without compromising acoustic behavior.
Implementation Method 1
The step of partly removing is carried out by means of a process of anisotropically etching the sacrificial material.
Data Source
AI summary
In accordance with one exemplary embodiment, a production method for a double-membrane MEMS component comprises the following steps: providing a layer arrangement on a carrier substrate, wherein the layer arrangement has a first and second membrane structure spaced apart from one another and a counterelectrode structure arranged therebetween, wherein a sacrificial material is arranged in an intermediate region between the counterelectrode structure and the first and second membrane structures respectively spaced apart therefrom, and wherein the first membrane structure has an opening structure to the intermediate region with the sacrificial material and partly removing the sacrificial material from the intermediate region in order to obtain a mechanical connection structure comprising the sacrificial material between the first and second membrane structures, which mechanical connection structure is mechanically coupled between the first and second membrane structures and is mechanically decoupled from the counterelectrode structure.