Investigation of the ability of a silica “seed” layer to improve the thermal and aqueous immersion stability of alkylsilane monolayers on silicon oxide surfaces

Anderson, Aaron S.; Ashurst, W. Robert

doi:10.1016/j.tsf.2008.04.103

Cited by 7 publications

(11 citation statements)

References 25 publications

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“…Data for clean SiO 2 is also listed for comparison. The contact angle values agree with those of other reports, , which indicates that the hydrophobic coatings of different precursors were successfully deposited on the Si wafers. No film thickness data is provided for the SiO 2 layer because it is considered as the substrate.…”

Section: Resultssupporting

confidence: 90%

Vapor-Phase Deposited Chlorosilane-Based Self-Assembled Monolayers on Various Substrates for Thermal Stability Analysis

Zhong

Chinn

Roberts

et al. 2017

Ind. Eng. Chem. Res.

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Chlorosilane-based self-assembled monolayers (SAMs), including octyltrichlorosilane (C8-OTS), (tridecafluoro-1,1,2,2-tetrahydrooctyl) trichlorosilane (FOTS) and dimethyldichlorosilane (DDMS), are applied on various substrates via a vapor-phase coating process for thermal stability analysis. Si(100) wafer dies and commercial vaporphase-deposited nanoparticle films are utilized as substrates to characterize the thermal stability enhancement. Atomic-force microscopy data prove that the vapor-based deposition technique results in a smooth surface with few aggregates. Contact angle goniometry data show that DDMS-based SAMs function effectively as the final protection layer for various substrates and these results are confirmed by thermogravimetric analysis of SAMs on the fumed silica supports. Quantitative analysis from X-ray photoelectron spectroscopy data shows that polymerized DDMS may exist on various surfaces and can contribute to the stable silane structures for DDMS. These test results yield improved understanding of thermal behavior of chlorosilane SAMs under high temperature and indicate that DDMS films are viable options for devices requiring low adhesion and high thermal stability.

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Section: Resultssupporting

confidence: 90%

Vapor-Phase Deposited Chlorosilane-Based Self-Assembled Monolayers on Various Substrates for Thermal Stability Analysis

Zhong

Chinn

Roberts

et al. 2017

Ind. Eng. Chem. Res.

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“…The relative intensities of these two peaks shows that the majority of the surface silanols that are consumed produce Si−O−Si bonds (through bridge bonding), but a small fraction of these silanol groups are converted to silanols of higher energy, which are less perturbed. Even though the vapor-deposited silica layers possess no free surface silanols, it has been demonstrated previously that they are amenable to surface modification by organosilane chemistries . Surface modification reactions by organosilicon precursors are generally described to proceed by a mechanism loosely depicted in Figure , which abounds in literature on this topic.…”

Section: Resultsmentioning

confidence: 99%

“…Samples are etched for 10 min in concentrated HF to remove the native oxide layer, rinsed in copious amounts of DI water, and then dried under a stream of nitrogen. The samples are loaded into a custom-built vacuum deposition system, which has been described previously, , for oxygen plasma treatment. A simplified schematic of the vacuum deposition system is shown in Figure A.…”

Section: Methodsmentioning

confidence: 99%

Investigation of a Vapor-Deposited Thin Silica Film: Morphological and Spectral Characterization

Anderson

Ashurst

2008

Langmuir

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Surface modification reactions by organosilicon compounds have demonstrated great success in a wide variety of applications. However, they are of limited usefulness in that they only proceed appreciably on surfaces that have an abundance of reactive hydroxyl groups, thus preventing their application to some materials of technological relevance, such as plastics and polymers. A process capable of depositing a surface rich in reactive hydroxyl groups onto a wide variety of substrates could potentially enable the extension of organosilane surface modification reactions to new materials, but conventional processes for depositing oxide layers require temperatures that are too high for most polymers and plastics. It has been shown that silica layers can be deposited from the vapor-phase hydrolysis of tetrachlorosilane at room temperature, but little if any work has been done to characterize the resulting films. In this work, ellipsometry, atomic force microscopy, and Fourier transform infrared spectroscopy are employed to study the characteristics of films formed from this process. Interestingly, very different film morphologies can be obtained by changing key processing parameters. Furthermore, isotopic exchange experiments and dehydration studies show that the surfaces of the silica films obtained by this method are composed entirely of hydrogen-bonded silanol groups and do not exhibit any freely vibrating surface silanol groups, a result that is in contrast with conventionally prepared silica materials. Still, this layer has been shown to behave very similarly to conventional silica materials with respect to surface reactions. Finally, infrared spectral data and contact angle data demonstrate that this method can be employed to deposit silica layers onto poly(methyl methacrylate) and polystyrene surfaces.

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“…A silicon ATR crystal and pieces from a silicon wafer are first sonicated in acetone and isopropanol for 10 min each and then dried under a stream of nitrogen. Then the samples are cleaned by an iterative HF etch/oxygen plasma process, which is described in detail elsewhere. , This iterative cleaning method is repeated until inspection by contact angle and AFM indicate that a clean (contact angle <5°), flat (rms roughness ∼0.2 nm) surface has been obtained (on samples cut from a silicon wafer), but usually two iterations suffice. After cleaning, the ATR crystal is fitted to the experimental apparatus (schematic available in Figure ), which is then evacuated to base pressure.…”

Section: Methodsmentioning

confidence: 99%

Interfacial Water Structure on a Highly Hydroxylated Silica Film

Anderson

Ashurst

2009

Langmuir

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Evidence suggests that in order for a surface to support an extensive water structure, it must possess sufficient Lewis cites so that water-surface interactions are favored over water-water interactions. In this paper we use ATR-FTIR to comparatively study, as a function of relative humidity, the water structure that exists on three surfaces: silicon, PEG-modified silicon, and a highly hydroxylated silica film which is formed from the room temperature, vapor phase hydrolysis of tetrachlorosilane. Results indicate that the PEG-modified silicon surface supports a water structure nearly 2.5 times as extensive as that which exists on unmodified silicon surfaces, which is an expected result in light of previous molecular dynamics simulations that indicate extensive hydrogen bonding between PEG monolayers and water molecules. The silica layer supports a water structure that is nearly an order of magnitude more extensive than that which exists on clean silicon surfaces and approximately 3.5 times more extensive than is adsorbed on PEG-modified silicon surfaces at similar relative humidities. Furthermore, the water layer on the silica surface exists mostly in an "ice-like" structure which is also more strongly hydrogen bonded than that which exists on clean silicon and PEG-modified silicon surfaces.

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Investigation of the ability of a silica “seed” layer to improve the thermal and aqueous immersion stability of alkylsilane monolayers on silicon oxide surfaces

Cited by 7 publications

References 25 publications

Vapor-Phase Deposited Chlorosilane-Based Self-Assembled Monolayers on Various Substrates for Thermal Stability Analysis

Vapor-Phase Deposited Chlorosilane-Based Self-Assembled Monolayers on Various Substrates for Thermal Stability Analysis

Investigation of a Vapor-Deposited Thin Silica Film: Morphological and Spectral Characterization

Interfacial Water Structure on a Highly Hydroxylated Silica Film

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