Fatigue-Induced Failure of Polysilicon MEMS: Nonlinear Reduced-Order Modeling and Geometry Optimization of On-Chip...

Area of Science:

• Materials Science
• Mechanical Engineering
• Nanotechnology

Background:

• Reliability of inertial microelectromechanical systems (MEMS) under repeated loadings is often limited by failure at movable structures or anchors.
• Debonding at the interface between polycrystalline silicon and silicon dioxide in MEMS anchors is a critical failure mechanism.
• Cyclic loading can induce fatigue failure, necessitating robust characterization of interface strength.

Purpose of the Study:

• To propose a strategy for optimizing the geometry of an on-chip testing device for characterizing MEMS interface strength.
• To analyze dynamic behavior and maximize stress concentration at the interface for improved debonding assessment.
• To develop a computationally efficient method for structural optimization in MEMS design.

Main Methods:

• Utilizing dynamic analyses to determine the deformation mode of the testing device.
• Implementing a reduced-order modeling procedure for nonlinear systems, specifically direct parametrization of invariant manifolds (DPIM).
• Performing structural optimization coupled with reduced-order modeling to efficiently simulate complex behaviors.

Main Results:

• The study identifies optimal geometries for the on-chip testing device to maximize interface stress intensification.
• Demonstrated the effectiveness of the DPIM methodology in reducing computational costs for nonlinear simulations.
• Quantified the impact of device geometry and actuation frequency on interface debonding.

Conclusions:

• The proposed methodology accurately and efficiently characterizes the strength of the polycrystalline silicon/silicon dioxide interface in MEMS.
• Optimized device geometry and understanding of failure mechanisms enhance the reliability of inertial MEMS.
• The DPIM approach offers a valuable tool for the structural optimization of MEMS devices under cyclic loading.