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Major, Ryan C.; Kim, H.I.; Houston, Jack E.; Zhu, Xiaoyang

doi:10.1023/a:1022628700342

Cited by 29 publications

(34 citation statements)

References 21 publications

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“…In experiments in which the friction force on a SAM was measured as a function of external load, some reports showed that the friction coefficient is inversely correlated with the alkyl-chain length of the SAM [18,19]. Our experiments in which we controlled the adhesion force showed a similar relation between the friction coefficient and chain length ( figure 7).…”

Section: Discussionsupporting

confidence: 71%

“…The other way is to directly reduce the friction force. Numerous reports describe effects of a SAM-coating on friction characteristics [14][15][16][17][18][19][20][21][22]. For example, Bliznyuk et al examined the friction coefficients of SAMs of alkylchlorsilanes and other monolayers on silicon substrates, and showed that the SAMs had a low friction coefficient [15].…”

Section: Introductionmentioning

confidence: 99%

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Tribological properties of asperity arrays coated with self-assembled monolayers

et al. 2007

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The effects of a self-assembled monolayer (SAM) coating on the friction and pull-off forces were determined by using twodimensional asperity arrays on silicon wafers. The arrays were coated with SAM composed of one of five different alkylchlorsilanes. First, two-dimensional asperity arrays were created by using a focussed ion beam (FIB) system to mill patterns on silicon plates. Each silicon plate had different patterns of equally spaced asperities. Each pattern (5 Â 5 lm 2 ) had a different radius of curvature of the asperity peaks, ranging from about 200 to 2500 nm. Then, each silicon plate was immersed in a solution of a different alkylchlorsilane in hexane (either hexyltrichlorosilane, octyltrichlorosilane, dodecyltrichlorosilane, tetradecyltrichlorosilane, or octadecyltrichlorosilane), thus coating the asperity arrays with SAM. The friction and pull-off forces on the SAM-coated arrays were measured by using an atomic force microscope (AFM) that had a square flat probe. The pull-off force for SAM-coated silicon was roughly proportional to the radius of curvature of the asperity peaks. The magnitude of the pull-off force corresponded approximately to the capillary force calculated by using the contact angle of water on the surface of SAM. The friction coefficient correlated with the inverse of the alkyl-chain length of the SAM.

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Section: Discussionsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Tribological properties of asperity arrays coated with self-assembled monolayers

et al. 2007

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“…The SAMs chemically bonded to the substrate are actually a better model for alkoxyl monolayers [32]. We do not expect the friction and adhesion studied here to depend on this bonding.…”

Section: Computational Proceduresmentioning

confidence: 86%

Frictional dynamics of perfluorinated self-assembled monolayers on amorphous SiO2

et al. 2005

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Silicon micromachines in microelectromechanical systems (MEMS) are coated with self-assembled monolayers (SAMs) in order to reduce the wear and stiction that are commonplace during operation. Recently, perfluorinated SAMs have been the focus of attention because they have better processing properties than hydrocarbon SAMs. In this study, we perform molecular dynamics simulations that model adhesive contact and friction for perfluorinated alkylsilane (Si(OH) 3 (CF 2 ) 10 CF 3 ) self-assembled monolayers (SAMs), which are commonly used in MEMS devices. Amorphous silica is used as the substrate for the SAMs in the simulations. The frictional behavior is investigated as a function of applied pressure (50 MPa-1 GPa) for a shear velocity of 2 m/s and compared to recent simulation results of hydrocarbon alkylsilane SAMs. The microscopic friction coefficient for the perfluorinated SAMs is the same as was measured for the hydrocarbon SAMs, but the shear stress is slightly larger than in the case of the hydrocarbon SAMs on amorphous silica.

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“…We have characterized the mechanical properties of monolayer lms by Interfacial Force Microscopy (IFM) [20,21]. This instrument is unique in that it consists of a noncompliant sensor which makes it possible to obtain accurate measurements of the complete tip /sample interaction force pro le, from attraction to repulsion.…”

Section: Mechanical Properties Of Monolayersmentioning

confidence: 99%

“…Measurements of friction as a function of normal force for silicon surfaces with alkoxyl monolayer assembly give friction coef cients on the order of 10 ¡2 for both dodecanol and octadecanol assembled surfaces [21]. The friction coef cient is related to molecular length and is shown to increase as the 598 Y. Jun and X. Zhu …”

Section: Mechanical Properties Of Monolayersmentioning

confidence: 99%

Alkoxyl monolayers as anti-stiction coatings in Si-based MEMS devices

Jun

Zhu

2003

Journal of Adhesion Science and Technology

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Reducing surface energy is key to the success of many microelectromechanical systems (MEMS). In this report we present a strategy for the ef cient assembly of alkoxyl monolayers onto a silicon surface to control surface energy. This is achieved by an all-liquid process in which the hydrogen terminated silicon surface resulting from aqueous HF etching is coated with a close-packed alkoxyl monolayer. The adhesion to silicon surface is reduced by a factor of 40 by the monolayer coating and friction coef cient of the coated surface is only 10 ¡2 . These coatings are successfully implemented in a model MEMS structure: cantilever beam array (CBA). Release-stictionis eliminated for polycrystalline silicon beams with a thickness of only 2 ¹m but with lengths up to 2 mm. Electrostatic actuation of coated beams in a controlled environment shows that the monolayer coating prevents in-use stiction at relative humidity as high as 90%.

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Untitled

Cited by 29 publications

References 21 publications

Tribological properties of asperity arrays coated with self-assembled monolayers

Tribological properties of asperity arrays coated with self-assembled monolayers

Frictional dynamics of perfluorinated self-assembled monolayers on amorphous SiO2

Alkoxyl monolayers as anti-stiction coatings in Si-based MEMS devices

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