MEMS Sensing Membrane Perforated Stress Release Structure
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Solution Overview
Problem
MEMS devices face challenges in sensitivity due to membrane residual stress, which is difficult to manage during manufacturing, especially when using complex materials with different coefficients of expansion, and the fixed membrane area limits the vibration frequency and device size.
Innovation Solution
A sensing membrane with a stress releasing structure featuring multiple perforations, including first, second, and third perforations, is designed to redistribute and release residual stress tangentially, improving sensitivity and reducing the membrane area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the membrane is made of complex materials with different coefficients of expansion, then the membrane structure can be formed during manufacturing, but membrane residual stress accumulates and reduces sensitivity
Solution Approach 1:
The membrane is segmented by introducing multiple perforations (first, second, and third perforations) that divide the continuous membrane structure into separated regions. This segmentation allows the membrane to release residual stress accumulated during manufacturing while maintaining the structural integrity needed for sensing functionality.
Solution Approach 2:
The membrane is transformed from a solid continuous structure to a porous structure with multiple perforations distributed throughout. These perforations create stress release pathways that reduce membrane residual stress, thereby improving sensitivity without compromising the membrane's structural formation during manufacturing.
2Volume of moving object
If the membrane area is reduced to decrease device volume, then the device size is reduced, but the vibration frequency changes and sensitivity may be affected
Solution Approach 1:
The perforations change the effective mechanical parameters of the membrane by creating stress release pathways. This allows the membrane to maintain optimal vibration frequency and sensitivity characteristics even when the overall membrane area is reduced, enabling smaller device volume without sacrificing performance.
3Productivity
If more MEMS elements are formed on each wafer to increase productivity, then production costs are lowered, but the membrane residual stress management becomes more difficult
Solution Approach 1:
The segmentation of the membrane through perforations provides a standardized stress management approach that can be replicated across multiple MEMS elements on a single wafer. This ensures consistent residual stress control across high-volume production, enabling increased productivity without compromising manufacturing precision.
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 stress releasing structure effectively reduces membrane residual stress, enhancing sensitivity and allowing for a smaller membrane area, thus reducing the overall volume of the MEMS device and lowering production costs by enabling more elements on each wafer.
Implementation Method 1
The sensing membrane releases the membrane residual stress by way of the stress releasing structure
Data Source
Figure 1~2A
Figure 2B
Figure 3
AI summary
A sensing membrane applied to a micro-electro-mechanical system (MEMS) device includes a body, a stress releasing structure and a connecting portion. The stress releasing structure for releasing a membrane residual stress surrounds the body. The stress releasing structure has several first perforations and several second perforations. The first perforations are located between the body and the second perforations. The connecting portion connects the stress releasing structure and a substrate of the MEMS device.