Tribological Properties of Modified MEMS Surfaces

Tsukruk, Vladimir V.; Nguyen, Tuan A.H.; LeMieux, Melburne C.; Hazel, J; Weber, W. H.; Shevchenko, V. V.; Клименко, Н. Н.; Shelud'ko, E. V.

doi:10.1007/978-94-011-5050-7_46

Cited by 22 publications

(16 citation statements)

References 5 publications

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“…Thicknesses of surface layers were also probed by spectroscopic ellipsometry. Thicknesses of the silicon oxide layer and CH 3 -, NH 2 -, and SO 3 H-terminated SAMs were determined to be 2.0−2.2, 2.0−2.5, 0.4−0.5, and 0.5−0.6 nm, respectively . These values are close to the ones expected for completely formed monolayers and detemined from SPM data .…”

Section: Resultssupporting

confidence: 72%

Adhesive and Friction Forces between Chemically Modified Silicon and Silicon Nitride Surfaces

1998

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We report the results of probing adhesion and friction forces between surfaces with functional terminal groups with chemically modified scanning probe microscopy (SPM) tips. Surfaces with terminal groups of CH3, NH2, and SO3H were obtained by direct chemisorption of silane-based compounds on silicon/silicon nitride surfaces. We studied surface properties of the resulting self-assembled monolayers (SAMs) in air and aqueous solutions with different pHs. Work of adhesion, “residual forces”, and friction coefficients was obtained for four different types of modified tips and surfaces. Absolute values of the work of adhesion between various surfaces, W ad, were in the range 0.5−8 mJ/m2. The work of adhesion for different modified surfaces correlated with changes of solid−liquid surface energy estimated from macroscopic contact-angle measurements. Friction properties varied with pH in a register with adhesive forces showing a broad maximum at intermediate pH values for a silicon nitride/silicon nitride mating pair. Similar broad maxima were observed in the acid range for a NH2-terminated SAM and in the basic range for a SO3H-terminated SAM. This behavior can be understood considering the changes of the surface charge state determined by the zwitterionic nature of silicon nitride surfaces with multiple isoelectric points.

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Section: Resultssupporting

confidence: 72%

Adhesive and Friction Forces between Chemically Modified Silicon and Silicon Nitride Surfaces

1998

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“…Some recent examples are molecular lubrication for microelectromechanical systems (MEMS) and biocompatible interfaces for biofunctionalized surfaces. , Mechanical stability always is a critical issue for tethered polymer layers, which affects their long-term durability under shear stresses. A concept of molecular lubrication through composite molecular layers has been recently proposed. , Composite molecular films firmly tethered to solid surfaces possess superior tribological properties due to the combination of the low shear strength of a supporting compliant sublayer and the high hardness of the rigid polymer layer . As a first example, we used amine- and sulfonic-terminated self-assembled monolayers (SAMs) capped with various rigid polymers and monomers …”

Section: Introductionmentioning

confidence: 99%

“…A concept of molecular lubrication through composite molecular layers has been recently proposed. , Composite molecular films firmly tethered to solid surfaces possess superior tribological properties due to the combination of the low shear strength of a supporting compliant sublayer and the high hardness of the rigid polymer layer . As a first example, we used amine- and sulfonic-terminated self-assembled monolayers (SAMs) capped with various rigid polymers and monomers …”

Section: Introductionmentioning

confidence: 99%

Sticky Molecular Surfaces: Epoxysilane Self-Assembled Monolayers

1999

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Dense, homogeneous, and complete self-assembled monolayers with epoxy surface groups were fabricated from epoxysilanes to serve as a template for chemical anchoring of ultrathin polymer layers. We formed epoxysilane layers on silicon oxide surfaces of silicon wafers, and a combination of scanning probe microscopy, ellipsometry, XPS, and contact angle measurements was used to study their morphology and surface properties. A low concentration of epoxysilane (less than 0.5 vol %) led to significant aggregate formation caused by a prevailing hydrolization/polymerization of epoxysilane molecules in bulk solution. Epoxysilane SAMs prepared from 1% solution were truly monomolecular films with a virtually normal molecular orientation of densely packed molecules, which were firmly attached to the substrate. Self-assembly deposition of epoxysilanes at optimal conditions resulted in the formation of homogeneous SAMs 0.85 ± 0.2 nm thick with the surface roughness 0.22 ± 0.05 nm.

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“…Technological applications, such as microelectromechanical systems , and magnetic storage devices, − have piqued interest in the potential use of organic films for boundary-layer lubricants. In these applications, the thickness of the lubricating films is approaching the monolayer regime.…”

Section: Introductionmentioning

confidence: 99%

Indentation Analysis of Linear-Chain Hydrocarbon Monolayers Anchored to Diamond

1999

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Classical molecular dynamics simulations are used to examine the indentation of monolayers composed of linear hydrocarbon chains with 8, 13, or 22 carbon atoms that are chemically bound (or anchored) to a diamond (111) substrate. Indentation is accomplished using both a flexible and rigid single-wall, capped [10,10] nanotube as the tip. Regardless of the nanotube used, the simulations show that indentation of the hydrocarbon monolayers causes a disruption of the original ordering of the monolayer, pinning of selected hydrocarbon chains beneath the tube, and the formation of gauche defects within the monolayer. Because nanotubes are stiff along their axial direction, the flexible nanotube is distorted only slightly by its interaction with the softer monolayers. However, interaction with the hard diamond substrate causes the tube to buckle. Severe indents with a rigid nanotube tip result in rupture of chemical bonds within the hydrocarbon monolayer.

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Tribological Properties of Modified MEMS Surfaces

Cited by 22 publications

References 5 publications

Adhesive and Friction Forces between Chemically Modified Silicon and Silicon Nitride Surfaces

Adhesive and Friction Forces between Chemically Modified Silicon and Silicon Nitride Surfaces

Sticky Molecular Surfaces: Epoxysilane Self-Assembled Monolayers

Indentation Analysis of Linear-Chain Hydrocarbon Monolayers Anchored to Diamond

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