MEMS Microphone Diaphragm Layout for Higher Sensitivity
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Solution Overview
Problem
The conventional electrode leading out method for micro-electro-mechanical system (MEMS) microphones with a cantilever structure fixing at the middle reduces the sensitivity of the microphone by interfering with the deformation of the vibrating diaphragm.
Innovation Solution
A MEMS microphone design where the electrode is connected only to the central region of the vibrating diaphragm, utilizing a fixing component at the central region to form a cantilever structure, with a notch and conductive components to ensure electrical connection without interfering with the diaphragm's edge deformation, and supported by additional rings to maintain vibration and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode is connected to the vibrating diaphragm using conventional methods, then electrical connection is achieved, but the electrode interferes with the deformation of the vibrating diaphragm and reduces sensitivity
Solution Approach 1:
The vibrating diaphragm is segmented into different regions: a central region where the electrode is connected, and an edge region where the electrode does not extend. This segmentation allows the electrode to provide electrical connection at the center while leaving the edge region free to deform fully, thus maintaining sensitivity. The notch structure further segments the diaphragm to create a clear separation between the electrode connection area and the vibration area.
Solution Approach 2:
Different regions of the vibrating diaphragm are given different functional qualities: the central region is optimized for electrical connection (with the electrode fixed to it), while the edge region is optimized for vibration (without electrode interference). The fixing component is located at the central region to provide stable connection, while the edge region remains free to deform under sound pressure, achieving local optimization of both electrical and mechanical functions.
2Stability of the object's composition
If the vibrating diaphragm is fully fixed to release residual stress, then structural stability is improved, but the electrode connection interferes with the deformation and reduces sensitivity
Solution Approach 1:
The fixing structure is segmented into a fixing component located at the central region of the vibrating diaphragm. This central fixing provides structural stability and releases residual stress effectively, while the edge region remains unfixed to allow full deformation. The electrode is connected only to the central region, ensuring that the fixing structure does not interfere with the edge region's vibration capability.
Solution Approach 2:
The fixing component acts as an intermediary element that provides structural stability and electrical connection at the central region without directly constraining the edge region. It mediates between the need for structural stability and the need for sensitivity by being positioned centrally, where it can provide support while allowing the edge to deform freely under sound pressure.
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
The design enhances the sensitivity of the MEMS microphone by fully releasing residual stress of the vibrating diaphragm, maintaining structural integrity and vibration efficiency.
Implementation Method 1
the vibrating diaphragm and the fixed back plate structure form a capacitor system. When a sound pressure acts on the vibrating diaphragm, there is a pressure difference between a first side of the vibrating diaphragm facing a back plate and a second of the vibrating diaphragm facing away from the back plate, thereby causing changes in capacitance between the vibrating diaphragm and the back plate
Data Source
AI summary
A MEMS microphone includes a substrate, a supporting plate, a capacitor system, a first pad, and a first electrode. The substrate defines a back cavity, the supporting plate is disposed at one side of the substrate and defines an accommodation cavity, and the capacitor system is disposed at the supporting plate. The capacitor system includes a back plate, a fixing component, and a vibrating diaphragm. The vibrating diaphragm is fixed to one side of the fixing component distal from the back plate. The vibrating diaphragm forms a cantilever structure fixing at the middle, and the first electrode is only connected to a central region of the vibrating diaphragm, the first electrode may not interfere with deformation of an edge region of the vibrating diaphragm, thereby improving sensitivity of the MEMS microphone through fully releasing residual stress of the vibrating diaphragm.