MEMS Microphone Membrane Stiffening for Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MEMS microphones have a mechanical sensitivity issue due to the static capacitance between the membrane and backplate, where the segment with the largest capacitance change contribution is relatively small, while the segment with the smallest contribution is large, leading to uneven sensitivity across the device.
Innovation Solution
A MEMS structure with a movable electrode featuring radial corrugation lines in the inner region for stiffness and circumferential corrugation lines in the outer region, allowing for a piston-type movement and increased capacitive change/sensitivity, formed through specific sacrificial layer processing and patterning techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the membrane and backplate are positioned close together to increase capacitance change, then the sensitivity contribution from the membrane center increases, but the static capacitance between membrane and backplate increases leading to reduced mechanical sensitivity
Solution Approach 1:
The membrane is divided into distinct functional zones: a stiff inner region (first region) and a flexible outer region (second region). This segmentation allows the inner region to provide stable capacitance change while the outer region compensates for static capacitance effects, resolving the contradiction between increasing capacitance change and maintaining mechanical sensitivity.
Solution Approach 2:
Different regions of the membrane are given different mechanical properties: the inner region is made stiff to maximize capacitance change contribution, while the outer region is made flexible to reduce static capacitance effects. This local differentiation of properties allows simultaneous optimization of both capacitance change and mechanical sensitivity.
2Reliability
If the membrane is made uniformly flexible to improve response, then the capacitive change contribution becomes uneven, but making it uniformly stiff increases static capacitance and reduces sensitivity
Solution Approach 1:
The membrane transitions from uniform flexibility to non-uniform flexibility with a stiff inner region and flexible outer region. The stiff inner region provides consistent capacitive response while the flexible outer region maintains uniform response characteristics, resolving the contradiction between response uniformity and capacitive change contribution.
Solution Approach 2:
The membrane is segmented into functional zones with different stiffness characteristics. The inner region (first region) provides stable capacitive contribution while the outer region (second region) ensures uniform response, together resolving the contradiction between response uniformity and capacitive change.
3Measurement precision
If the inner region of the membrane is made stiffer to increase capacitance change, then the capacitive contribution from the center increases, but the outer region becomes overly flexible causing uneven sensitivity distribution
Solution Approach 1:
The membrane is designed with locally differentiated properties where the inner region is stiff for high capacitance change and the outer region is flexible for uniform response distribution. This local quality differentiation resolves the contradiction between maximizing capacitance change and maintaining even sensitivity distribution.
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 solution enhances the capacitive change and sensitivity of the MEMS device by creating a stiff inner region and flexible outer region, improving the membrane's deflection characteristics and overall sensitivity distribution.
Implementation Method 1
The movable electrode is configured to stiffen an inner region of the movable membrane
Implementation Method 2
the segment with the largest capacitance change contribution is relatively small, while the segment with the smallest contribution is large
Data Source
AI summary
A MEMS device and a method of making a MEMS device are disclosed. In one embodiment a semiconductor device comprises a substrate, a moveable electrode and a counter electrode, wherein the moveable electrode and the counter electrode are mechanically connected to the substrate. The movable electrode is configured to stiffen an inner region of the movable membrane.