The effect of humidity on the reliability of a surface micromachined microengine

Tanner, Darren; Walraven, Jeremy A.; Irwin, Lloyd W.; Dugger, Michael Thomas; Smith, Norman F.; Eaton, William P.; Miller, William M.; Miller, S. L.

doi:10.1109/relphy.1999.761611

Cited by 50 publications

(48 citation statements)

References 18 publications

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“…Adhesion and friction play a critical role in determining the operational reliability and lifetimes of such systems [19]. One of the main causes of adhesion and friction problems of MEMS is the presence of a thin water film present on most surfaces.…”

Section: Introductionmentioning

confidence: 99%

Nanofriction Mechanisms Derived from the Dependence of Friction on Load and Sliding Velocity from Air to UHV on Hydrophilic Silicon

et al. 2005

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Abstract. This paper examines friction as a function of the sliding velocity and applied normal load from air to UHV in a scanning force microscope (SFM) experiment in which a sharp silicon tip slides against a flat Si(100) sample. Under ambient conditions, both surfaces are covered by a native oxide, which is hydrophilic. During pump-down in the vacuum chamber housing the SFM, the behavior of friction as a function of the applied normal load and the sliding velocity undergoes a change. By analyzing these changes it is possible to identify three distinct friction regimes with corresponding contact properties: (a) friction dominated by the additional normal forces induced by capillarity due to the presence of thick water films, (b) higher drag force from ordering effects present in thin water layers and (c) low friction due to direct solid-solid contact for the sample with the counterbody. Depending on environmental conditions and the applied normal load, all three mechanisms may be present at one time. Their individual contributions can be identified by investigating the dependence of friction on the applied normal load as well as on the sliding velocity in different pressure regimes, thus providing information about nanoscale friction mechanisms.

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Section: Introductionmentioning

confidence: 99%

Nanofriction Mechanisms Derived from the Dependence of Friction on Load and Sliding Velocity from Air to UHV on Hydrophilic Silicon

et al. 2005

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“…It has been demonstrated that humidity is a strong factor in the wear of rubbing surfaces in polysilicon microfabrication. The operation of MEMS in a very low humidity environment can lead to much greater amounts of wear debris than operation at higher humidity [56], [57]. As wear debris agglomerates, third body wear can be initiated which is often evidenced by scratches on surface.…”

Section: Wearmentioning

confidence: 99%

MEMS Reliability Review

Huang

Vasan

Doraiswami

et al. 2012

IEEE Trans. Device Mater. Relib.

153

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Abstract-Microelectromechanical systems (MEMS) represents a technology that integrates miniaturized mechanical and electromechanical components (i.e., sensors and actuators) that are made using microfabrication techniques. MEMS devices have become an essential component in a wide range of applications, ranging from medical and military to consumer electronics. As MEMS technology is implemented in a growing range of areas, the reliability of MEMS devices is a concern. Understanding the failure mechanisms is a prerequisite for quantifying and improving the reliability of MEMS devices. This paper reviews the common failure mechanisms in MEMS, including mechanical fracture, fatigue, creep, stiction, wear, electrical short and open, contamination, their effects on devices' performance, inspection techniques, and approaches to mitigate those failures through structure optimization and material selection.

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“…The gear rotates about a hub that is anchored to the substrate. The microengine has been the focus of much investigation for MEMS devices experiencing sliding friction [3][4][5].…”

Section: The Temperaturesmentioning

confidence: 99%

“…Parts fabricated from polysilicon, a material originally developed for its electronic properties, have been demonstrated to be mechanically robust [2]. However, wear has been identified as a significant failure mechanism for devices with load beming surfaces [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Selective W for Coating and Releasing MEMS Devices

et al. 1999

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Nation~Laborato~es, Albuquerque, NM 8'7 185-m$4~~F=g $p~,s smani @sandia.gov JAlll~1; $$;; ' ABSTRACT cil~~jTwo major problems associated with Si-based MEMS (MicroElectro~echanical Systems) " devices are stiction and wear. Surface modifications are needed to reduce both adhesion and friction in rnicromechanical structures to solve these problems. In this paper, we will present a CVD (Chemical Vapor Deposition) process that selectively coats MEMS devices with tungsten and significantly enhances device durability. Tungsten CVD is used in the integrated-circuit industry, which makes this approach manufacturable. This selective deposition process results in a very conforrnal coating and can potentially address both stiction and wear problems confronting MEMS processing. The selective deposition of tungsten is accomplished through the silicon reduction of Wl%. The self-limiting nature of this selective W deposition process ensures the consistency necessary for process-control. The tungsten is deposited after the removal of the sacrificial oxides to minimize stress and process integration problems. Tungsten coating adheres well and is hard and conducting, requirements for device performance. Furthermore, since the deposited tungsten infiltrates-under adhered silicon parts and the volume of W deposited is less than the amount of Si consumed, it appears to be possible to release stuck parts that are contacted over small areas such as dimples. The wear resistance of selectively coated W parts has been shown to be significantly improved on microengine test structures.

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The effect of humidity on the reliability of a surface micromachined microengine

Cited by 50 publications

References 18 publications

Nanofriction Mechanisms Derived from the Dependence of Friction on Load and Sliding Velocity from Air to UHV on Hydrophilic Silicon

Nanofriction Mechanisms Derived from the Dependence of Friction on Load and Sliding Velocity from Air to UHV on Hydrophilic Silicon

MEMS Reliability Review

Selective W for Coating and Releasing MEMS Devices

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