Characterization of Accelerated Fatigue in Thick Epi-Polysilicon Vacuum Encapsulated MEMS Resonators

Alter, Anne L.; Flader, Ian B.; Chen, Yunhan; Ortiz, Lizmarie Comenencia; Shin, Dongsuk D.; Kenny, Thomas W.

doi:10.1109/jmems.2020.3021947

Cited by 4 publications

(3 citation statements)

References 42 publications

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“…Different attempts to obtain Wöhler curves of micromechanical samples were made [28][29][30][31][32][33][34][35][36], on the other hand, few works applying Paris' law to characterize fatigue fracture process in MEMS devices exist in the literature [20,[37][38][39].…”

Section: Siliconmentioning

confidence: 99%

Fatigue fracture mechanics in gold-based MEMS notched specimens: experimental and numerical study

Pistorio

Somà

2023

J. Micromech. Microeng.

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The characterization of fatigue fracture mechanics in gold-MEMS notched specimens is presented in this work. A test microstructure with a central notched specimen is specifically designed and built to perform on-chip fatigue test. The central specimen undergoes cyclic loading due to the application of alternating voltage. The variation in the microstructure deflection is measured using an optical profilometer and is attributed to the crack growth in the gold material, causing the variation in the specimen stiffness. The occurrence of pull-in condition is used as a fracture detector, then the fracture of the specimen can be recognized without performing scanning electron microscope inspections during the fatigue test. Crack propagation in the test specimen is simulated through a coupled-field electromechanical fracture finite element model and the computed crack path is compared to the results obtained from scanning electron microscope analyses. Finally, Paris' law is applied and the number of cycles to failure is computed by exploiting the results of the fracture model and experimental measurements. Both experimental and numerical results demonstrate that the notch acts as a stress and strain raiser, fostering crack nucleation from the notch root, and that the linear elastic fracture mechanics theory is still valid to describe crack propagation in micro-size samples.

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Section: Siliconmentioning

confidence: 99%

Fatigue fracture mechanics in gold-based MEMS notched specimens: experimental and numerical study

Pistorio

Somà

2023

J. Micromech. Microeng.

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“…• Environmental effect: In particular, there is a significant effect of humidity, and no fatigue failure of single-crystal silicon is observed in an ultra-high-vacuum environment [82]. However, polycrystalline silicon shows fatigue failure in the same environment [83]. • Stiffness change is observed as a resonant frequency shift during cyclic loading, but this is not associated with fatigue failure occurrence.…”

Section: Mechanismsmentioning

confidence: 99%

Mechanical reliability of silicon microstructures

Tsuchiya¹

2021

J. Micromech. Microeng.

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In this article, an overview of the mechanical reliability of silicon microstructures for micro-electro-mechanical systems (MEMS) is given to clarify what we now know and what we still have to know about silicon as a high-performance mechanical material on the microscale. Focusing on the strength and fatigue properties of silicon, attempts to understand the reliability of silicon and to predict the device reliability of silicon-based microstructures are introduced. The effective parameters on the strength and the mechanism of fatigue failure are discussed with examples of measurement data to show the design guidelines for highly reliable silicon microstructures and devices.

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“…This creates a low pressure, particlefree, and oxide-free environment that enables the resonators to be extremely stable over time [12]. This process also creates siliconbased resonators with smooth sidewalls, which ensures repeatable mechanical properties and prevents crack formation, or fatigue [13]. Additionally, no sealing rings are required, so device footprint is minimized.…”

Section: Introductionmentioning

confidence: 99%

Etch-Hole Free, Large Gap Wafer Scale Encapsulation Process for Microelectromechanical Resonators

Vukasin,

Bousse,

Alter

et al. 2022

2022 Solid-State, Actuators, and Microsystems Workshop Technical Digest

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We present a fabrication process for wafer-level encapsulated MEMS devices that allows for large masses without etch-holes with small and large transduction gaps. This combination of features allows for large masses with combdrive transduction with reduced thermoelastic dissipation. The omission of wafer bonding in this process reduces the footprint of an encapsulated device and creates a hermetically sealed cavity free of particles and organics. We present the performance of a bulk mode resonator (Q = 1.7M) and a flexural mode resonator (Q = 11k, 68k) that utilizes the small and large transduction gap capability. These devices exemplify the ability of this fabrication process to create single die containing high-Q silicon-based timing references and inertial sensors.

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Characterization of Accelerated Fatigue in Thick Epi-Polysilicon Vacuum Encapsulated MEMS Resonators

Cited by 4 publications

References 42 publications

Fatigue fracture mechanics in gold-based MEMS notched specimens: experimental and numerical study

Fatigue fracture mechanics in gold-based MEMS notched specimens: experimental and numerical study

Mechanical reliability of silicon microstructures

Etch-Hole Free, Large Gap Wafer Scale Encapsulation Process for Microelectromechanical Resonators

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