MEMS Microphone Support Structures for Acoustic Overload
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MEMS microphones face challenges in increasing the acoustic overload point (AOP) without compromising the signal-to-noise ratio (SNR) and sensitivity, as methods to enhance membrane stiffness often require adjusting bias voltage.
Innovation Solution
Incorporating support structures between the membranes and the base plate in MEMS microphones, made of insulating materials, to increase membrane stiffness without altering the bias voltage, thereby improving AOP and SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If membrane stiffness is increased to improve acoustic overload point (AOP), then AOP is improved, but signal-to-noise ratio (SNR) and sensitivity deteriorate
Solution Approach 1:
The membrane structure is segmented by introducing support structures (posts) that divide the membrane into multiple regions. These support structures are positioned at specific locations to provide localized stiffness enhancement without affecting the overall membrane flexibility required for acoustic sensitivity. The membrane is thus divided into flexible sensing regions and rigid support regions, resolving the contradiction between stiffness and sensitivity.
Solution Approach 2:
Instead of uniformly increasing membrane stiffness, the invention applies stiffness enhancement locally through support structures positioned at specific locations (e.g., corners or edges of the membrane). This local quality approach allows the membrane to maintain flexibility in acoustic sensing areas while gaining stiffness in specific regions to improve AOP, thereby preserving SNR and sensitivity.
2Strength
If membrane stiffness is increased by adjusting bias voltage, then AOP is improved, but device complexity and control difficulty increase
Solution Approach 1:
The invention replaces the electrical control mechanism (bias voltage adjustment) with a mechanical solution (support structures). Instead of dynamically controlling membrane stiffness through voltage changes, the support structures provide permanent mechanical reinforcement. This substitution eliminates the need for complex voltage control circuits while achieving the desired stiffness enhancement for improved AOP.
3Strength
If support structures are added to increase membrane stiffness, then AOP is improved, but device complexity increases
Solution Approach 1:
The support structures are designed as thin, minimally invasive elements that maintain the overall thin-film nature of the MEMS microphone membrane. These flexible support structures provide necessary stiffness enhancement while preserving the lightweight, simple structure characteristic of thin-film MEMS devices, thus improving AOP without significantly increasing device complexity.
Data Source
AI summary
A micro electro mechanical system (MEMS) microphone includes a first membrane, a second membrane, a third membrane disposed between the first membrane and the second membrane, a first cavity disposed between the first membrane and the third membrane and surrounded by a first wall, a second cavity disposed between the second membrane and the third membrane and surrounded by a second wall, and one or more first supports disposed in the first cavity and connecting the first membrane and the third membrane.