Segmented Counter Electrode for MEMS Vacuum Microphone Parasitic Capacitance
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Solution Overview
Problem
Microelectromechanical system (MEMS) devices, such as microphones, face challenges in achieving high signal-to-noise ratios due to parasitic capacitances that interfere with the intended capacitance signals, particularly in double backplate microphone designs, leading to suboptimal sound reproduction.
Innovation Solution
The implementation of a MEMS device with a segmented counter electrode structure and membrane elements in a low-pressure region, where the counter electrode is split into electrically isolated portions to reduce parasitic capacitances, enhancing the signal-to-noise ratio by differentially reading out the membrane elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double backplate microphone design is used, then the device can function as a MEMS microphone, but parasitic capacitances interfere with the capacitance signals and degrade signal-to-noise ratio
Solution Approach 1:
The counter electrode is segmented into multiple electrically isolated portions, which reduces parasitic capacitances by preventing capacitive coupling between adjacent conductive regions. This segmentation allows the device to maintain its double backplate microphone functionality while significantly reducing the harmful parasitic effects that degrade signal-to-noise ratio.
2Volume of moving object
If continuous miniaturization is pursued to improve device integration, then device size is reduced, but achieving high signal-to-noise ratio becomes more difficult due to increased parasitic effects
Solution Approach 1:
By segmenting the counter electrode into electrically isolated portions, the patent enables miniaturization while maintaining high signal-to-noise ratio. The segmentation reduces parasitic capacitances that would otherwise become more significant in smaller devices, allowing continuous miniaturization to proceed without sacrificing performance.
3Ease of manufacture
If a conductive layer is used in the low pressure region, then the counter electrode structure can be formed, but parasitic capacitances influence the electrical output signal and prevent accurate sound reproduction
Solution Approach 1:
The conductive layer is segmented into electrically isolated portions, which maintains the ease of manufacture by allowing standard fabrication processes while eliminating parasitic capacitance interference. This segmentation ensures that the electrical output signal accurately reflects the sound input signal without distortion from parasitic effects.
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 significantly reduces parasitic capacitances, thereby improving the signal-to-noise ratio and ensuring more accurate sound signal reproduction in MEMS devices like microphones and loudspeakers.
Implementation Method 1
a low pressure region between the first and second membrane elements, the low pressure region having a pressure less than an ambient pressure
Implementation Method 2
a low pressure region between the first and second membrane elements, the low pressure region having a pressure less than an ambient pressure
Implementation Method 3
parasitic capacitances are usually unwanted capacitances interfering with capacitances between both the membrane and the counter electrode
Data Source
AI summary
In accordance with an embodiment, a MEMS device includes a first membrane element, a second membrane element spaced apart from the first membrane element, a low pressure region between the first and second membrane elements, the low pressure region having a pressure less than an ambient pressure, and a counter electrode structure comprising a conductive layer, which is at least partially arranged in the low pressure region or extends in the low pressure region. The conductive layer includes a segmentation providing an electrical isolation between a first portion of the conductive layer and a second portion of the conductive layer.