Encapsulated Moving Electrode MEMS Microphone Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MEMS microphone systems face challenges in efficiently encapsulating moving electrodes while maintaining sensitivity and minimizing mechanical stiffening, which affects the microphone's ability to detect acoustic signals effectively.
Innovation Solution
The proposed MEMS microphone system incorporates a package housing with a lid, spacer, and substrate, where the moving electrode is encapsulated within a vacuum or low-pressure region between membranes, and the electrode is mechanically coupled to the membranes via thin posts to minimize stiffening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the moving electrode is encapsulated within a vacuum or low-pressure region, then the microphone's sensitivity is enhanced and membranes can bend without collapsing, but the device complexity increases due to the need for encapsulation structures
Solution Approach 1:
The moving electrode is nested within the encapsulation structure formed by the first and second membranes, with the vacuum/low-pressure region nested between these membranes. This nested configuration allows the sensitive electrode to be protected and maintained in a controlled pressure environment while integrating compactly within the microphone device.
Solution Approach 2:
The thin posts act as intermediaries that mechanically couple the moving electrode to the membranes while minimizing stiffening effects. These intermediary elements transfer mechanical support from the membranes to the electrode without significantly increasing the overall structural rigidity, thus maintaining membrane compliance.
2Stability of the object's composition
If thin posts are used to mechanically couple the electrode to the membranes, then mechanical stiffening is minimized and membrane compliance is maintained, but the strength of the mechanical connection is reduced
Solution Approach 1:
The membranes are designed as thin, flexible structures that maintain compliance while providing mechanical support. These thin film structures are optimized to be sufficiently flexible to allow electrode movement and signal generation, yet strong enough to provide stable mechanical coupling through the thin posts.
Solution Approach 2:
The design optimizes the parameters of the thin posts (dimensions, material properties, attachment geometry) to achieve the right balance between mechanical strength and minimal stiffening. By carefully controlling post thickness, length, and material, the connection strength is sufficient while the stiffening effect on the large membranes remains minimal.
3Measurement precision
If large membranes are used to improve acoustic signal detection, then the sensitivity increases, but the membranes may collapse without sufficient mechanical support
Solution Approach 1:
The vacuum or low-pressure region acts as a counterbalancing force that supports the large membranes from collapsing. By creating a pressure differential across the membranes, the external atmospheric pressure provides a supporting force that counteracts the tendency of large, thin membranes to collapse inward, allowing them to maintain their large area for sensitive acoustic detection.
Solution Approach 2:
The thin posts serve as intermediary mechanical support elements that distribute loads across the membrane structure. These posts provide localized support points that prevent membrane collapse while maintaining the overall large membrane area needed for sensitive acoustic signal detection.
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 enhances the microphone's sensitivity by allowing large, compliant membranes that can bend without collapsing, while maintaining efficient particle removal and reducing parasitic capacitance for improved signal readout.
Implementation Method 1
reducing parasitic capacitance for improved signal readout
Implementation Method 2
the electrode is mechanically coupled to the membranes via thin posts to minimize stiffening
Implementation Method 3
allowing large, compliant membranes that can bend without collapsing
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A MEMS microphone system with encapsulated movable electrode is provided. The MEMS microphone system comprises a MEMS sensor having an access channel, a plug, and first and second members. The access channel configured to receive the plug is formed on at least one of the first and second member. A vacuum having a pressure different from a pressure outside the MEMS sensor is formed between the first and second members.