MEMS Piezoelectric Microphone S-Shaped Membrane to Reduce Sound Leakage
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Solution Overview
Problem
MEMS microphones with piezo-electric structures face performance degradation due to sound waves leaking through gaps between petals of the piezo-membrane and the entry of dust and particles, which affect signal quality.
Innovation Solution
Forming an approximate S-shape in the flexible portion of the piezo-membrane with a lower portion at least 1 μm different from the upper portion to maintain a mismatch below 6 μm, reinforcing the membrane and reducing sound wave leakage and particle entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the piezo-membrane is separated into multiple petals, then the manufacturing process is simplified and assembly is easier, but gaps between petals allow sound waves to leak and particles to enter
Solution Approach 1:
The piezo-membrane is divided into multiple petals that are separated and can be manufactured independently, simplifying the manufacturing process and enabling easier assembly while maintaining the functional integrity of the membrane through precise alignment features
Solution Approach 2:
Alignment features act as intermediaries between the petals, ensuring precise positioning and minimizing gaps between adjacent petals. These features serve as mediators that maintain signal quality by preventing sound wave leakage and particle ingress while allowing the segmented structure to function effectively
2Reliability
If the gap between petals is reduced to prevent sound wave leakage, then signal quality improves, but manufacturing precision requirements increase
Solution Approach 1:
Alignment features are incorporated into the petal design beforehand, enabling precise positioning to be achieved during assembly without requiring extremely tight manufacturing tolerances on the petal edges themselves. This preliminary incorporation of alignment mechanisms reduces the overall manufacturing precision burden
Solution Approach 2:
The design transitions from controlling gap size through tight manufacturing tolerances to controlling gap size through geometric alignment features. This parameter change shifts the control mechanism from dimensional precision to positional geometry, making the system more robust to manufacturing variations
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
Enhances the performance of MEMS microphones by minimizing sound wave leakage and particle ingress, thereby improving signal fidelity and reliability.
Implementation Method 1
Some MEMS microphones use a piezo-electric structure that converts mechanical strains into electrical signals
Data Source
AI summary
An approximate S-shape is formed in a non-sensing portion of a micro-electromechanical systems (MEMS) microphone. For example, a piezo-electric layer, in a semiconductor stack forming the non-sensing portion, may have a lower portion at a first point that is at least 1 micrometer (μm) below the lower portion at a second point. The approximately S-shape reinforces a piezo-membrane including the non-sensing portion and results in mismatch between petals of the piezo-membrane remaining closer to zero (e.g., within 6 μm). As a result, fewer incoming sound waves leak through a gap between petals of the piezo-membrane, and performance of the MEMS microphone is increased. Additionally, the gap between the petals is less likely to allow dust and other small particles to enter the MEMS microphone, which further improves performance of the MEMS microphone.