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Maboudian, Roya; Ashurst, W. Robert; Carraro, Carlo

doi:10.1023/a:1014044207344

Cited by 240 publications

(125 citation statements)

References 36 publications

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“…Silicon, however, is quite brittle and subject to several reliability concerns -most importantly, stiction [1,2] , wear [1,3] and fatigue -that can limit the utility of silicon MEMS devices in commercial and defense applications. Currently, there are many commercial silicon-based MEMS devices that are subjected to various environments and forms of periodic loading, sometimes at very high frequency, such as resonators found in both radio frequency as well as MEMS sensor applications.…”

Section: Introduction To Fatigue Of Micron-scale Siliconmentioning

confidence: 99%

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

et al. 2007

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SummaryAlthough bulk silicon is not susceptible to fatigue, micron-scale silicon is. Several mechanisms have been proposed to explain this surprising behavior although the issue remains contentious. Here we describe published fatigue results for micron-scale thin silicon films and find that in general they display similar trends, in that lower cyclic stresses result in larger number of cycles to failure in stress-lifetime data. We further show that one of two classes of mechanisms is invariably proposed to explain the phenomenon. The first class attributes fatigue to a surface effect caused by subcritical (stable) cracking in the silicon-oxide layer, e.g., reaction-layer fatigue; the second class proposes that subcritical cracking in the silicon itself is the cause of fatigue in Si films. It is our contention that results to date from single and poly crystalline silicon fatigue studies provide no convincing experimental evidence to support subcritical cracking in the silicon. Conversely, the reaction-layer mechanism is consistent with existing experimental results, and moreover provides a rational explanation for the marked difference in fatigue behavior of bulk and micron-scale silicon.

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Section: Introduction To Fatigue Of Micron-scale Siliconmentioning

confidence: 99%

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

et al. 2007

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“…This is because silicon can be microfabricated to produce complex mechanical structures in thin-film form because of highly developed processing methods directly related to semiconductor electronics processing. 1,2 However, silicon is not an ideal structural material: it is quite brittle and subject to several reliability concerns-most importantly, stiction, 3,4 wear, 3,5 and fatigue [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] -that strongly limit the utility of silicon MEMS devices in commercial and defense applications. In particular, premature fatigue failure can occur when devices are subjected to a large number ͑ϳ10 6 -10 12 ͒ of loading cycles at stress amplitudes well below their monotonic fracture stress.…”

Section: Introductionmentioning

confidence: 99%

Very high-cycle fatigue failure in micron-scale polycrystalline silicon films: Effects of environment and surface oxide thickness

Alsem

Timmerman

Boyce

et al. 2007

Journal of Applied Physics

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Fatigue failure in micron-scale polycrystalline silicon structural films, a phenomenon that is not observed in bulk silicon, can severely impact the durability and reliability of microelectromechanical system devices. Despite several studies on the very high-cycle fatigue behavior of these films (up to 1012cycles), there is still an on-going debate on the precise mechanisms involved. We show here that for devices fabricated in the multiuser microelectromechanical system process (MUMPs) foundry and Sandia Ultra-planar, Multi-level MEMS Technology (SUMMiT V™) process and tested under equi-tension/compression loading at ∼40kHz in different environments, stress-lifetime data exhibit similar trends in fatigue behavior in ambient room air, shorter lifetimes in higher relative humidity environments, and no fatigue failure at all in high vacuum. The transmission electron microscopy of the surface oxides in the test samples shows a four- to sixfold thickening of the surface oxide at stress concentrations after fatigue failure, but no thickening after overload fracture in air or after fatigue cycling in vacuo. We find that such oxide thickening and premature fatigue failure (in air) occur in devices with initial oxide thicknesses of ∼4nm (SUMMiT V™) as well as in devices with much thicker initial oxides ∼20nm (MUMPs). Such results are interpreted and explained by a reaction-layer fatigue mechanism. Specifically, moisture-assisted subcritical cracking within a cyclic stress-assisted thickened oxide layer occurs until the crack reaches a critical size to cause catastrophic failure of the entire device. The entirety of the evidence presented here strongly indicates that the reaction-layer fatigue mechanism is the governing mechanism for fatigue failure in micron-scale polycrystalline silicon thin films.

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“…Fluorocarbons are known to have lower critical surface tensions compared to hydrocarbons and perfluoronated trichlorosilanes are the most effective chlorosilane reagents to produce hydrophobic coatings. [14] In general, perfluoronated SAMs are known to have a higher hydrophobicity compared to hydrocarbon SAMs. [24] Stability: Following the surface modification we studied the stability under various conditions.…”

Section: Membrane Materialsmentioning

confidence: 99%

Chemical and Thermal Stability of Alkylsilane Based Coatings for Membrane Emulsification

et al. 2004

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Conclusions:The experimentally determined values of the power indices x and c describing dependence of conductivity r~f v and permittivity e~f ±c on AC frequency f in polyisoprene-carbon nanocomposite in the vicinity of percolation threshold are consistent with the general scaling principle of the percolation theory v + c = 1. The obtained values of v and c are in agreement with the mechanism of inter-cluster polarisation.The experimentally observed deviation from the relation e~|M-M C | ±s of the statistical percolation theory at carbon concentrations above the percolation threshold M > M C may be a result of particle agglomeration and deviation from statistical distribution. The asymmetric and branching shapes of particle clusters cause strong local electric fields in the matrix between clusters providing additional contribution to the dielectric permittivity.

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Untitled

Cited by 240 publications

References 36 publications

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

Very high-cycle fatigue failure in micron-scale polycrystalline silicon films: Effects of environment and surface oxide thickness

Chemical and Thermal Stability of Alkylsilane Based Coatings for Membrane Emulsification

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