Slotted Insulative Layer for MEMS Diaphragm Stress Relief
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Solution Overview
Problem
Multi-layered diaphragms in MEMS acoustic transducers face performance degradation due to coefficient of thermal expansion (CTE) mismatch between layers, leading to stress and reduced acoustic sensitivity.
Innovation Solution
Incorporating a slotted insulative layer that decouples and reduces stress between layers by allowing slots to open up upon stress relaxation, thereby enhancing acoustic compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a multi-layered diaphragm is used in a MEMS acoustic transducer, then the diaphragm can provide structural support and electrical insulation, but performance degradation occurs due to CTE mismatch between layers causing stress
Solution Approach 1:
The insulative layer is segmented by forming slots through it, dividing the continuous layer into isolated regions. This segmentation allows each region to independently accommodate thermal expansion differences, reducing stress while maintaining structural support. The slots create discrete segments that can move relative to each other, preventing stress accumulation across the entire layer.
Solution Approach 2:
The insulative layer is transformed into a porous structure by forming slots through it. This porous configuration provides pathways for stress relief while maintaining the mechanical integrity and insulative properties of the layer. The void spaces created by slots allow the material to better accommodate dimensional changes due to thermal expansion.
2Reliability
If a multi-layered diaphragm is used in a MEMS acoustic transducer, then the diaphragm can provide electrical insulation between conductive layers, but acoustic sensitivity is reduced due to stress from CTE mismatch
Solution Approach 1:
The insulative layer is segmented by forming slots through it, dividing the continuous layer into isolated regions. This segmentation allows each region to independently accommodate thermal expansion differences, reducing stress while maintaining structural support. The slots create discrete segments that can move relative to each other, preventing stress accumulation across the entire layer.
Solution Approach 2:
The insulative layer is transformed into a porous structure by forming slots through it. This porous configuration provides pathways for stress relief while maintaining the mechanical integrity and insulative properties of the layer. The void spaces created by slots allow the material to better accommodate dimensional changes due to thermal expansion.
3Stress or pressure
If slots are disposed through the insulative layer, then the two layers are decoupled and stress is minimized, but the structural continuity of the insulative layer is disrupted
Solution Approach 1:
The insulative layer is transformed into a porous structure by forming slots through it. This porous configuration provides pathways for stress relief while maintaining the mechanical integrity and insulative properties of the layer. The void spaces created by slots allow the material to better accommodate dimensional changes due to thermal expansion.
Solution Approach 2:
The slots are strategically positioned and sized to create local variations in the insulative layer structure. The regions between slots maintain full structural continuity and mechanical strength, while the slot regions provide stress relief. This local differentiation allows the layer to simultaneously achieve both structural integrity and stress minimization.
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 slotted layer effectively reduces stress and improves acoustic compliance, addressing the limitations of conventional multi-layer diaphragms with corrugation features.
Implementation Method 1
Slots disposed through one of the layers as presented herein decouples the two layers while also minimizing the stress in the slotted layer
Data Source
AI summary
An MEMS acoustic transducer includes a substrate having an opening formed therein, a diaphragm comprising a slotted insulative layer, and a first conductive layer. The slotted insulative layer is attached around a periphery thereof to the substrate and over the opening, and the first conductive layer is disposed on a first surface of the slotted insulative layer. A backplate is separated from the diaphragm and disposed on a side of the diaphragm opposite the substrate.