Capacitive MEMS Sound Transducer Segmented Electrode Parasitic Capacitance
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Solution Overview
Problem
Capacitive MEMS devices, such as microphones and speakers, face challenges in achieving a high signal-to-noise ratio due to parasitic capacitances that interfere with the intended capacitance signals, particularly in miniaturized designs used in devices like mobile phones and laptops.
Innovation Solution
A capacitive MEMS device with a multiple-segmented conductive layer structure, where the second conductive layer is split into portions by segmentation lines, providing electrical isolation and reducing parasitic capacitances, thereby increasing the transfer factor and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conductive layer is segmented into multiple portions, then parasitic capacitances are reduced and signal-to-noise ratio is improved, but device complexity increases due to additional segmentation structures
Solution Approach 1:
The first conductive layer is divided into multiple segmented portions (e.g., first, second, and third portions) that are electrically isolated from each other. This segmentation reduces parasitic capacitances between the conductive layer and the second electrode structure, thereby improving the signal-to-noise ratio of the capacitive MEMS device.
2Measurement precision
If the conductive layer is segmented to reduce parasitic capacitances, then transfer factor is increased, but manufacturing complexity increases due to additional fabrication steps
Solution Approach 1:
The conductive layer is segmented into multiple electrically isolated portions during the fabrication process. This segmentation increases the transfer factor by reducing parasitic capacitances, while the process is integrated into the existing MEMS fabrication workflow.
Solution Approach 2:
A dielectric layer is deposited over the segmented conductive layer to provide electrical isolation between the segmented portions and the second electrode structure. This dielectric intermediary enables the reduction of parasitic capacitances while maintaining a manufacturable structure.
3Measurement precision
If multiple segmentation lines are used to electrically isolate conductive portions, then parasitic capacitance reduction is enhanced, but structural complexity increases
Solution Approach 1:
Multiple segmentation lines are introduced to divide the conductive layer into several electrically isolated portions. Each segmentation line creates additional electrical isolation, thereby enhancing parasitic capacitance reduction. The segmented portions are arranged to optimize capacitance management while controlling structural complexity.
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 multiple segmentation of the conductive layer significantly reduces parasitic capacitances, enhancing the signal-to-noise ratio by increasing the transfer factor, which results in a stronger output signal with reduced damping of sound pressure conversions.
Implementation Method 1
parasitic capacitances are usually unwanted capacitances interfering with capacitances between the membrane and the counter electrode
Implementation Method 2
depositing a dielectric layer onto the first conductive layer and into the gaps in the first conductive layer
Data Source
AI summary
A capacitive MEMS device, a capacitive MEMS sound transducer, a method for forming a capacitive MEMS device and a method for operating a capacitive MEMS device are disclosed. In an embodiment the capacitive MEMS device includes a first electrode structure comprising a first conductive layer and a second electrode structure comprising a second conductive layer, wherein the second conductive layer at least partially opposes the first conductive layer, and wherein the second conductive layer includes a multiple segmentation which provides an electrical isolation between at least three portions of the second conductive layer.