MEMS Microphone Electrode Segmentation for Sensitivity
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Solution Overview
Problem
Current microphones, particularly MEMS microphones, face challenges in sensitivity due to the limited design of their vibration films and electrode configurations, which affect their ability to accurately detect sound pressure changes.
Innovation Solution
The microphone design includes a substrate with a penetration aperture, a polysilicon or silicon nitride vibration film, a first electrode with separated portions, a piezoelectric layer on the edge portion, and a fixed electrode with air inlets, allowing for improved sound detection through both capacitance and piezoelectric signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the vibration film is designed with uniform structure, then the manufacturing process is simple, but the sensitivity to sound pressure changes is insufficient
Solution Approach 1:
The first electrode is divided into two separate portions: a first portion at the center of the vibration film and a second portion at the edge of the vibration film. This segmentation allows different regions to serve different functions - the center portion for capacitance detection and the edge portion for piezoelectric detection - thereby improving overall sensitivity without excessive complexity
Solution Approach 2:
Different portions of the electrode structure are assigned different functions based on their location. The first portion at the center utilizes capacitance changes, while the second portion at the edge utilizes piezoelectric effects. This local differentiation optimizes the detection capability at each region, improving sensitivity while maintaining manufacturing simplicity
2Measurement precision
If only capacitance detection is used, then the structure is simple, but the sensitivity is limited
Solution Approach 1:
The patent combines two detection mechanisms - capacitance detection and piezoelectric detection - into a single microphone structure. The first electrode portion detects sound pressure through capacitance changes, while the second electrode portion detects through piezoelectric effects. This merging of detection mechanisms improves sensitivity by utilizing multiple physical principles simultaneously
Solution Approach 2:
The electrode structure serves multiple functions: the first portion functions as a capacitance sensor, while the second portion functions as a piezoelectric sensor. This multi-functionality allows the microphone to detect sound pressure changes through multiple pathways, enhancing sensitivity without requiring separate detection devices
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 configuration enhances the microphone's sensitivity by enabling effective detection of sound pressure changes at the edge of the vibration film, where minimal vibration width occurs, thereby improving sound sensing capabilities.
Implementation Method 1
a piezoelectric layer disposed on the second portion of the first electrode and made of a piezoelectric material
Implementation Method 2
when sound pressure is applied to the vibration film from the exterior, a capacitance value is changed while an interval between the fixed electrode and the vibration film is also changed
Data Source
AI summary
A microphone and method of manufacturing the microphone are provided. The microphone includes a substrate that has a penetration aperture, a vibration film disposed on the substrate that covers the penetration aperture, and a first electrode disposed on the vibration film. The first electrode includes a first portion and a second portion separated from each other. In addition, the microphone includes a piezoelectric layer disposed on the second portion of the first electrode, a second electrode disposed on the piezoelectric layer, and a fixed electrode. Further, the first portion of the first electrodes is disposed at a substantially center portion of the vibration film and the second portion of the first electrode is disposed at an edge portion of the vibration film.