Tunable MEMS Device Segmented Electrode Parasitic Capacitance
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Solution Overview
Problem
MEMS microphones face challenges in reducing parasitic capacitance and achieving tunable mechanical sensitivity post-fabrication, which limits signal-to-noise ratio (SNR) due to fixed dimensions and overlap between the membrane and backplate.
Innovation Solution
The implementation of a segmented electrode configuration, where a first region provides a sensing signal and a second region is tunable, laterally spaced from the sensing region, allowing for reduction of parasitic capacitance and adjustment of mechanical sensitivity by capacitive actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the membrane and backplate are overlapped with fixed dimensions, then the mechanical sensitivity is determined, but the parasitic capacitance increases and the signal-to-noise ratio deteriorates
Solution Approach 1:
The backplate is divided into a first region and a second region that are laterally spaced apart. The first region overlaps with the membrane to provide mechanical support and define the sensing area, while the second region is positioned away from the membrane to provide tuning capacitance. This segmentation allows the parasitic capacitance to be reduced by separating the sensing function from the tuning function, thereby improving the signal-to-noise ratio.
2Adaptability or versatility
If the membrane and backplate dimensions are fixed during fabrication, then the manufacturing process is simplified, but the mechanical sensitivity cannot be adjusted post-fabrication
Solution Approach 1:
The backplate is designed with a dynamic electrode configuration where the second region can be laterally displaced relative to the membrane. This displacement is controlled by applying voltages to the segmented electrodes, allowing the mechanical sensitivity to be tuned after fabrication. The dynamic adjustment capability enables the device to adapt to different sensing requirements without requiring complex fabrication processes.
3Force
If the overlap area between membrane and backplate is increased, then the mechanical sensitivity is improved, but the parasitic capacitance increases
Solution Approach 1:
The backplate is segmented into a first region that overlaps with the membrane to provide mechanical sensitivity and a second region that is laterally spaced to provide tuning capacitance. This segmentation allows the mechanical sensitivity to be optimized by the overlap area in the first region while the parasitic capacitance is controlled by positioning the second region away from the membrane, thereby decoupling the two competing requirements.
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 approach significantly reduces parasitic capacitance, enabling tunable mechanical sensitivity and improved signal-to-noise ratios by decoupling capacitances, allowing for different sensitivity configurations with the same MEMS structure.
Implementation Method 1
allowing for reduction of parasitic capacitance and adjustment of mechanical sensitivity by capacitive actuation
Data Source
AI summary
A tunable MEMS device and a method of manufacturing a tunable MEMS device are disclosed. In accordance with an embodiment of the present invention, a semiconductor device comprises a substrate, a moveable electrode and a counter electrode. The moveable electrode or the counter electrode comprises a first region and a second region, wherein the first region is isolated from the second region, wherein the first region is configured to be tuned, wherein the second region is configured to provide a sensing signal or control a system, and wherein the moveable electrode and the counter electrode are mechanically connected to the substrate.