Surface Topology and Fatigue in Si MEMS Structures

Allameh, Seyed M.; Gally, Brian; Brown, Stuart B.; Soboyejo, WO

doi:10.1520/stp10976s

Cited by 20 publications

(10 citation statements)

References 13 publications

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“…Based on a wide spectrum of studies (listed in Tables 1 and 2) involving a range of different testing methods (described in the Appendix), stress-lifetime data (Figures 1, 10) for thin-film silicon show relatively consistent trends, specifically that stress amplitudes as low as half the (single-cycle) fracture stress can cause delayed fatigue failure, typically after 10 11 cycles or more [11,24,31,33,48] . Such fatigue failure has been reported for various modes of cyclic loading, specifically for fully reversed cyclic loading (R = -1) [4,[11][12][13][14][15]18,19,24,[30][31][32][33][34][35][41][42][43]48,49,[52][53][54]59] and tensile loading with a positive mean stress (R ≥ 0) [13,[21][22][23][25][26][27][28][29][33][34][35]40,[55]…”

Section: Discussionmentioning

confidence: 99%

“…A complementary mechanism to reaction-layer fatigue was proposed by Allameh, Soboyejo, and coworkers [12,[52][53][54] , who studied the evolution of surface morphology of polysilicon MEMS during cyclic actuation, using the same fatigue resonators as Muhlstein et al (Figure 2). In situ AFM images of the region near the notch, before and after cyclic actuation at a stress amplitude of 2.7 GPa for 2 × 10 9 cycles, revealed definitive changes in surface topology ( Figure 16).…”

Section: Figurementioning

confidence: 91%

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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: Discussionmentioning

confidence: 99%

Section: Figurementioning

confidence: 91%

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

et al. 2007

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“…Indeed, there has been no evidence to date that bulk silicon is susceptible to fatigue failure. However, there is substantial evidence that cyclically-stressed micron-scale films of silicon can fail at stresses well below the (single-cycle) fracture strength [1][2][3][4][5][6][7][8][9]17]. …”

Section: Introductionmentioning

confidence: 99%

A reaction-layer mechanism for the delayed failure of micron-scale polycrystalline silicon structural films subjected to high-cycle fatigue loading

2002

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Abstract-A study has been made of high-cycle fatigue in 2-µm thick structural films of n + -type, polycrystalline silicon for MEMS applications. Using an "on-chip" test structure resonating at ~40 kHz, such thin-film polysilicon is shown to display "metal-like" stress-life fatigue behavior in room air environments, with failures occurring after lives in excess of 10 11 cycles at stresses as low as half the fracture strength. Through in-situ monitoring of the natural frequency to evaluate the damage evolution by notch-root oxidation and cracking, and using transmission electron microscopy to image such damage, it is concluded that the mechanism of thin-film silicon fatigue involves sequential oxidation and environmentallyassisted cracking in the native SiO 2 layer. This moisture-induced "reaction-layer fatigue" mechanism can also occur in bulk silicon but it is only significant in thin films where the critical crack size for catastrophic failure can be reached by a crack growing within the oxide layer. The susceptibility of thin-film silicon to fatigue failure is shown to be suppressed by the use of alkene-based self-assembled monolayer coatings that prevent the formation of the native oxide.

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“…It is, therefore, recommended that the focused ion beam (FIB) is used for a clean observation of the cross-sectional area of the MEMS structures [93,94].…”

Section: Fatigue In Memsmentioning

confidence: 99%

Reliability and Fatigue Analysis in Cantilever-Based MEMS Devices Operating in Harsh Environments

Jan

Hamid

Khir

et al. 2014

Journal of Quality and Reliability Engineering

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The microelectromechanical system (MEMS) is one of the most diversified fields of microelectronics; it is rated to be the most promising technology of modern engineering. MEMS can sense, actuate, and integrate mechanical and electromechanical components of micro-and nano sizes on a single silicon substrate using microfabrication techniques. MEMS industry is at the verge of transforming the semiconductor world into MEMS universe, apart from other hindrances; the reliability of these devices is the focal point of recent research. Commercialization is highly dependent on the reliability of these devices. MEMS requires a high level of reliability. Several technological factors, operating conditions, and environmental effects influencing the performances of MEMS devices must be completely understood. This study reviews some of the major reliability issues and failure mechanisms. Specifically, the fatigue in MEMS is a major material reliability issue resulting in structural damage, crack growth, and lifetime measurements of MEMS devices in the light of statistical distribution and fatigue implementation of Paris' law for fatigue crack accumulation under the influence of undesirable operating and environmental conditions.

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Surface Topology and Fatigue in Si MEMS Structures

Cited by 20 publications

References 13 publications

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

A reaction-layer mechanism for the delayed failure of micron-scale polycrystalline silicon structural films subjected to high-cycle fatigue loading

Reliability and Fatigue Analysis in Cantilever-Based MEMS Devices Operating in Harsh Environments

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