MEMS Cantilever Structure With Vertical Membrane For Sensitivity
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Solution Overview
Problem
Conventional piezoelectric MEMS sensors with cantilever structures suffer from uneven stress distribution, leading to low sensitivity due to the structural design of the diaphragm, which affects their performance in sensing environmental signals.
Innovation Solution
The integration of a membrane vertically coupled with a MEMS structure, featuring multiple cantilever portions with free and anchor ends, increases the sensing area by connecting the membrane to the free ends of the cantilever portions, thereby enhancing stress concentration and sensitivity without enlarging the device dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional diaphragm with cantilever structure is used, then the device dimensions can be kept compact, but the sensing area is limited and stress distribution is uneven, leading to low sensitivity
Solution Approach 1:
The patent introduces a membrane positioned above the cantilever structure at a specific distance, creating a three-dimensional sensing configuration. This vertical arrangement allows the membrane to provide additional sensing area without increasing the planar footprint, effectively transitioning from a two-dimensional to a three-dimensional sensing approach that resolves the contradiction between compact dimensions and increased sensing area
Solution Approach 2:
The membrane is positioned within the space above the substrate, nesting the additional sensing structure within the existing device volume. This nested configuration allows the membrane to contribute to sensing area without requiring additional lateral space, thereby maintaining compact device dimensions while improving sensitivity
2Measurement precision
If the sensing area is increased to improve sensitivity, then more material and larger device dimensions are required, but this increases device complexity and size
Solution Approach 1:
By utilizing the vertical dimension to position the membrane above the cantilever structure, the patent achieves increased sensing area without proportional increases in device footprint or structural complexity. The vertical stacking approach allows multiple sensing elements to coexist in a compact configuration, reducing the complexity-to-performance ratio
Solution Approach 2:
The membrane serves multiple functions: it provides additional sensing area for improved sensitivity, acts as a stress distribution element, and maintains a simple planar structure that does not significantly increase fabrication complexity. This multi-functionality allows the membrane to contribute to sensitivity improvement without proportionally increasing device 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
This configuration improves the sensitivity of MEMS devices by increasing the sensing area and electrical signal output, applicable for both piezoelectric and piezoresistive sensors, including pressure sensors, microphones, and accelerometers, while maintaining the same device dimensions.
Implementation Method 1
conventional piezoelectric MEMS sensor including a diaphragm has been used in most applications
Implementation Method 2
applicable for both piezoelectric and piezoresistive sensors
Data Source
AI summary
A MEMS device includes a substrate having a cavity, and a MEMS structure disposed over the cavity and attached to the substrate. The MEMS structure includes a plurality of cantilever portions, where each cantilever portions includes a free end and an anchor end. The MEMS device further includes a membrane disposed over the MEMS structure and includes a plurality of protruding portions respectively connected to the free ends of the cantilever portions. In addition, the MEMS device includes a gap between the MEMS structure and the membrane, where the gap surrounds the protruding portions.