MEMS Microphone Semiconductor Pillars for AOP and Particle Control
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Solution Overview
Problem
MEMS microphones face a trade-off between achieving high signal-to-noise ratio (SNR) and acoustic overload point (AOP), with contaminants in the air gap reducing membrane vibration and sensitivity, and particles entering the air gap causing malfunction.
Innovation Solution
Incorporating semiconductor or insulating pillars to enhance membrane stiffness and reduce particle entry, while maintaining sensitivity and SNR through vent holes and air flow channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the air gap is enlarged to improve AOP, then acoustic overload point is improved, but particle entry risk increases and sensitivity decreases
Solution Approach 1:
The patent employs a thin film membrane structure that maintains high sensitivity while providing sufficient mechanical strength. The membrane is designed with optimized thickness and material properties to detect acoustic signals effectively while withstanding acoustic overload conditions without requiring a large air gap.
Solution Approach 2:
The patent uses composite material structures for the membrane and surrounding components, combining materials with different properties to achieve both high sensitivity for acoustic detection and sufficient rigidity to prevent particle entry and withstand acoustic pressure without enlarging the air gap.
2Stress or pressure
If membrane stiffness is increased to improve AOP, then acoustic overload point is improved, but sensitivity is reduced
Solution Approach 1:
The patent applies local quality by creating regions of different stiffness within the membrane structure. The membrane has varying thickness or material composition in different areas, allowing it to be stiff enough to prevent particle entry and withstand acoustic overload while maintaining sensitivity in the active detection regions.
Solution Approach 2:
The patent uses a thin film membrane with optimized mechanical properties that provides sufficient stiffness to improve AOP while maintaining the flexibility needed for sensitive acoustic detection. The film structure is designed to balance rigidity and flexibility locally.
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
Improves AOP without reducing bias voltage, mitigates particle and air damping issues, and enhances performance by maintaining sensitivity and SNR.
Implementation Method 1
Incorporating semiconductor or insulating pillars to enhance membrane stiffness
Implementation Method 2
maintaining sensitivity and SNR through vent holes and air flow channels
Data Source
AI summary
A MEMS device includes a first multi-layer structure, a second multi-layer structure over the first multi-layer structure, a first semiconductor layer between the first and second multilayer structures, a first air gap separating the first multi-layer structure and the first semiconductor layer, a second air gap separating the first semiconductor layer and the second multi-layer structure, a plurality of semiconductor pillars, and a plurality of second semiconductor pillars. The first semiconductor pillars are exposed to the first air gap, and coupled to the first semiconductor layer and the first multi-layer structure. The second semiconductor pillars are exposed to the second air gap, and coupled to the first semiconductor layer and the second multi-layer structure.