MEMS Microphone Segmented Backplate for Low-Noise Differential Sensing
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Solution Overview
Problem
Existing MEMS microphones with differential capacitive structures face complex manufacturing processes, high chip costs, low yield rates, and poor reliability due to the need for additional layers in their three-layer symmetric structure.
Innovation Solution
A MEMS microphone design that uses a support to divide the backplate into two electrode regions, forming inner and outer capacitors without adding extra layers, allowing for increased diaphragm area and ensuring frequency bandwidth while reducing noise and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a three-layer symmetric structure is adopted for differential capacitive MEMS microphone, then the performance in THD and AOP is improved, but the manufacturing process becomes complex, chip cost increases, yield rate decreases, and reliability deteriorates
Solution Approach 1:
The patent merges the functions of multiple layers into a single backplate structure. The backplate integrates both the capacitive function and the structural support function that were previously distributed across three separate layers. This consolidation eliminates the need for additional diaphragm or backplate layers, simplifying the manufacturing process while maintaining the differential capacitive structure's acoustic performance.
Solution Approach 2:
The backplate is designed to serve multiple functions simultaneously: it forms the capacitive structure with the diaphragm, provides structural support, creates the acoustic cavity boundary, and enables the differential measurement function. This multi-functional design eliminates the need for separate dedicated layers for each function, reducing manufacturing complexity and improving yield rate.
2Measurement precision
If a three-layer symmetric structure is adopted for differential capacitive MEMS microphone, then the performance in THD and AOP is improved, but chip cost increases and yield rate decreases
Solution Approach 1:
The patent merges the functions of multiple layers into a single backplate structure. The backplate integrates both the capacitive function and the structural support function that were previously distributed across three separate layers. This consolidation eliminates the need for additional diaphragm or backplate layers, simplifying the manufacturing process while maintaining the differential capacitive structure's acoustic performance.
3Measurement precision
If a three-layer symmetric structure is adopted for differential capacitive MEMS microphone, then the performance in THD and AOP is improved, but reliability deteriorates
Solution Approach 1:
The patent merges the functions of multiple layers into a single backplate structure. The backplate integrates both the capacitive function and the structural support function that were previously distributed across three separate layers. This consolidation eliminates the need for additional diaphragm or backplate layers, simplifying the manufacturing process while maintaining the differential capacitive structure's acoustic performance.
4Object-affected harmful factors
If the diaphragm area is increased to reduce noise and improve signal-to-noise ratio, then the acoustic performance is improved, but the frequency bandwidth may be compromised
Solution Approach 1:
The patent segments the backplate into two distinct electrode regions: a first back-electrode region facing the inner suspended region and a second back-electrode region facing the outer suspended region. This segmentation allows each region to independently interact with its corresponding diaphragm portion, enabling the large diaphragm area to function effectively across a broad frequency range without compromising bandwidth.
Solution Approach 2:
The patent applies different local qualities to different regions of the backplate and diaphragm system. The inner suspended region and outer suspended region have different mechanical properties and vibration characteristics, allowing the system to optimize both low-frequency noise reduction (through large area) and high-frequency response (through localized vibration modes).
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 design enhances the overall performance of the microphone by increasing diaphragm area, reducing noise, and improving signal-to-noise ratio through the use of a differential capacitor without additional structures, thus optimizing acoustic performance.
Implementation Method 1
the diaphragm and the backplate form a capacitive structure which is divided into an inner capacitor and an outer capacitor by the support
Implementation Method 2
the inner suspended region is capable of being excited by sound pressure to vibrate mechanically
Data Source
AI summary
Disclosed are a MEMS microphone and an electronic device. The MEMS microphone comprises a substrate, a diaphragm, and a backplate. The backplate is formed with a support, and comprises a first back-electrode region and a second back-electrode region which are connected to different electrodes.