MEMS Transducer Membrane With Segmented Arms and Variable Vent
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Solution Overview
Problem
MEMS transducers, particularly capacitive microphones, face challenges in surviving mechanical shocks and high-pressure impulses due to their design, which can lead to damage from sudden pressure changes, and there is a need to reduce the footprint of these devices on silicon wafers for increased efficiency and sensitivity.
Innovation Solution
The introduction of a MEMS transducer design featuring a membrane with a central region and stress-distributing arms that support the membrane, along with a variable vent structure and stress diffusing structures, to alleviate stress concentrations and provide a controlled pressure relief mechanism, allowing for efficient acoustic performance and reduced footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a membrane is supported around its entire periphery to provide uniform stress distribution, then manufacturing precision is improved, but the device footprint increases
Solution Approach 1:
The membrane support structure is segmented into discrete arms extending from a central region rather than continuous peripheral support. This segmentation allows the membrane to be supported at specific locations while reducing the overall footprint area, resolving the contradiction between manufacturing precision and device size.
Solution Approach 2:
The support structure transitions from two-dimensional peripheral support to a three-dimensional configuration with arms extending upward and outward from a central region. This dimensional change enables compact footprint while maintaining adequate support for stress distribution.
2Reliability
If bleed holes are provided in the membrane to equalize pressure between cavities, then reliability is improved, but acoustic performance deteriorates
Solution Approach 1:
Different regions of the membrane have different properties: the central region contains bleed holes for pressure equalization, while the peripheral region maintains acoustic integrity. This local differentiation allows the membrane to simultaneously achieve reliability through pressure equalization and maintain acoustic performance by preserving the peripheral structure.
Solution Approach 2:
Instead of providing complete peripheral support or numerous bleed holes throughout the membrane, the invention uses partial support through discrete arms and limited bleed holes only in the central region. This partial action approach maintains adequate pressure equalization while minimizing impact on acoustic performance.
3Measurement precision
If the membrane is made larger to improve sensitivity, then measurement precision is improved, but the device footprint increases
Solution Approach 1:
The membrane structure utilizes three-dimensional space with arms extending vertically and radially from a central region, allowing a larger effective membrane area for improved sensitivity while maintaining a compact footprint. The vertical extension of arms provides additional structural support without increasing the planar footprint area.
Solution Approach 2:
The membrane structure combines different functional regions: a central region with bleed holes for pressure equalization and peripheral regions with arms for structural support and stress distribution. This composite structure achieves both sensitivity and compact size by optimizing different regions for different functions.
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 transducer's ability to withstand high-pressure events, maintains acoustic performance, and optimizes the use of silicon wafer space by reducing the required area for transducer fabrication, enabling more devices to be produced on a given wafer without compromising sensitivity.
Implementation Method 1
a flexible membrane which is free to move in response to pressure differences generated by sound waves
Implementation Method 2
the membrane is moved by electrostatic forces generated by varying a potential difference applied across the electrodes
Implementation Method 3
measuring the capacitance between the electrodes
Data Source
AI summary
A MEMS transducer may comprise a membrane supported relative to a substrate, the membrane comprising a first region and a second region, wherein the first region comprises a central region and plurality of arms which extend laterally from the central region and wherein the second region is separated from the first region by a channel which extends through the membrane.