Reactions of Organosilanes with Silica Surfaces in Carbon Dioxide

Cao, Chuntao; Fadeev, and Alexander Y.; McCarthy, Thomas J.

doi:10.1021/la000849t

Cited by 89 publications

(70 citation statements)

References 44 publications

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“…Iron(III)TIM complexes also have been isolated and characterized for CO and SCN 1 ligands and detected in solution for thiolate ligands. 34 Based on solution kinetic data for acetonitrile replacement by neutral amines, available in the literature 18 for [FeTIM(CH 3 CN) 2 ] 2C and in our studies in solution by absorption spectroscopy in the visible region for FeTIM in the presence of ten times more concentrated 3-APTS (not shown), we expect facile substitution of one acetonitrile by the -NH 2 group of the grafted 3-APTS. This 3-APTS binding to FeTIM in solution causes a strong red shift in max for the metal-to-ligand charge transfer (MLCT) band peak position (C N p Fe d ) from 552 to 623 nm.…”

Section: Resultsmentioning

confidence: 53%

“…Prior to the organomodification of silicon, cleaning in 10% (v/v) HF solution for 15 s at room temperature to remove the native oxide and then a three-step oxidation were carried out: H 2 14,17 to obtain smooth and clean surfaces of SiO 2 /Si.…”

Section: Silicon Wafer Preparationmentioning

confidence: 99%

“…1,2 These compounds usually consist of three alkoxide groups at one extremity, of which one or more groups can be hydrolysed and subsequently bound to the surface. The other extremity is typically an organofunctional group, which can be bound to any of a variety of ligand units acting as Lewis bases.…”

Section: Introductionmentioning

confidence: 99%

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Surface chemistry of the iron tetraazamacrocycle on the aminopropyl‐modified surface of oxidized n‐Si(100) by AFM and XPS

Magalhães

Moreira

Rodrigues-Filho

et al. 2002

Surface & Interface Analysis

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The structure and formation mechanisms of 3-aminopropyltrimethoxysilane (3-APTS) films deposited on wet-chemically grown silicon dioxide over n-Si(100) wafer have been examined systematically using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The asymmetric N 1s XPS spectrum for the anchored 3-APTS was fitted for -NH 2 (399.6 ± 0.3 eV) and -NH 3 + (401.1 ± 0.3 eV). Rougher surfaces are obtained by deposition from toluene solutions than from the gaseous phase. Over the 3-APTS layer was deposited the [FeTIM(CH 3 CN) 2 ]2+ complex, where TIM is 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene. The adsorption occurs by acetonitrile replacement for the-NH 2 -grafted group with the equatorial plane parallel to the organomodified surface. Once FeTIM can bind a CO, NO or N-heterocycle, a built-on Si wafer sensor device could be envisaged for these molecules.

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Section: Resultsmentioning

confidence: 53%

Section: Silicon Wafer Preparationmentioning

confidence: 99%

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Surface chemistry of the iron tetraazamacrocycle on the aminopropyl‐modified surface of oxidized n‐Si(100) by AFM and XPS

Magalhães

Moreira

Rodrigues-Filho

et al. 2002

Surface & Interface Analysis

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“…[17] The favorable transport properties of supercritical CO 2 , including low viscosity and zero surface tension, offer additional opportunities for the post-synthesis surface modification of metal oxides, including silylation and other surface modifications of porous materials. [18,19] Unlike reactions in liquid solvents, surface modification in CO 2 does not require a subsequent drying step. Moreover, the absence of surface tension in supercritical solutions prevents the collapse of nanoscale features in device structures and mesoporous films, which is a major disadvantage of liquid-based processes.…”

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confidence: 99%

Synthesis of Mesoporous Organosilicate Films in Supercritical Carbon Dioxide

Pai

Watkins

2006

Advanced Materials

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ered with a thin fluorocarbon film. This wafer acted as a handling substrate for the resist. After spin-coating, the polymer was gently softbaked at 40°C to evaporate the solvent. The SU-8 was then structured by UV lithography (k= 365 nm) and post-exposure-baked at 40°C to polymerize the exposed material. Three-dimensional microsystems were achieved by adding further SU-8 layers and repeating the resist processing steps. The microdevices were finally developed in propylene glycol methyl ether acetate (PGMEA) to remove the unexposed SU-8. After development, the SU-8 structures were released from the fluorocarbon-coated handling wafer by tweezers. The fluorocarbon film exhibits low free surface energy, which reduced the adhesion between the resist and the wafer and eased the release [17]. Before the experiments for stress tailoring, the polymer structures were hardbaked in an oven at 120°C for 30 min to remove residual resist solvent, which could affect the processing. Moreover, the polymer surface was cleaned in oxygen plasma. [1] sensing and detection, [2] low-k dielectrics, [3] separation, [4] and numerous other areas. Their utility depends primarily on their framework chemistry and morphology, but in some cases pore-surface composition, periodicity of the pore structure, and long-range order are defining factors. Conventional methods for preparation are based on the cooperative assembly of network-forming precursors and structure-directing organic templates, such as surfactants or block copolymers. These methods include sol-gel processes via spin-coating [5] and dip-coating, [6] and hydrothermal processes at the liquid/air and the solid/liquid interfaces. [7] More recently, hybrid mesoporous materials functionalized with organic groups at the internal pore surfaces [8,9] or containing functional organic groups distributed homogeneously within the framework [10,11] have been prepared. Films of homogeneous composition can be directly obtained by direct cocondensation of the silica precursor, tetraethylorthosilicate (TEOS), and organosilicate precursors containing the desired functional group. Alternatively, post-synthesis functionalization of the internal pore surfaces of mesoporous materials can modify the performance of silicate materials with respect to adsorption, wetting, and catalytic properties. [8,12,13] One potential limitation is that the extent of grafting can be limited by the accessibility and number of surface silanol groups. To date, most reports deal with the synthesis of granular materials by either or both of these methods. Numerous applications, however, require uniform, defect-free films. Here, we focus on the rapid preparation of device-quality films using an alternative approach in supercritical carbon dioxide. This work significantly extends our recent report of a novel method of synthesis of ordered mesostructured films for use as low-k dielectrics by the selective mineralization of preorganized block-copolymer templates in supercritical carbon diox- COMMUNICATIONS

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“…Silylation of native oxide silicon surface in preparation for coating of hydrophobic photoresits can be conducted in supercritical CO 2 . The use of CO 2 as a green alternative carrier to vapor or solution phase reactions for the silane reagents reduces the consumption of chemicals and improves surface coverage rate [12] .…”

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confidence: 99%

Supercritical CO2-based solvents in next generation microelectronics processing

Zhang

Johnston²

2007

CHINESE SCI BULL

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Large amount of chemicals and highly purified-water are needed in microelectronic manufacture. The ability of solutions to penetrate tiny spaces will become significantly more challenging as the feature size of semiconductor devices decreases to nanoscale dimensions and the functional complexity of integrated circuitries (ICs) ever increases. Supercritical fluids (SCFs) possess a unique combination of properties (no surface tension and gas-like viscosity) that can potentially be exploited for application in microelectronics manufacturing and processing in response to needs for material-compatible cleaning systems, small-dimension developing solvents, and low chemical-use processes. Recent microelectronics processes for cleaning and rinsing of patterned porous low-k dielectrics and drying of photoresist in CO 2 -based solvents are the main focus of this review. Additional topics in supercritical fluid processing include spin coating of photoresists, development with nanoscale dimensions, metal deposition and silylation.supercritical carbon dioxide, low-k dielectrics cleaning, photoresist drying A manufacture method for semiconductor devices includes many steps: coating, photolithography, etching and ashing, cleaning, drying, etc. Incorporating new low-dielectric isolation materials and low-resistance metals (Cu replacing Al as interconnects) will be required in next generation microelectronic processing. As the features in semiconductor devices shrink to nanoscale dimensions, a major hurdle will emerge in processing steps involving lithography coating, development, metal deposition, cleaning, and drying. In addition, encouraged by increased regulations on the release of toxic chemicals and costs of water and solvent use, the semiconductor industry is eager to abate chemical and water usage in main production processes. Therefore, new concepts in semiconductor manufacture are required to challenge this complexity.Supercritical CO 2 (Sc CO 2 )-based technologies accept a number of such challenges. The solvation properties of CO 2 are unique. The high compressibility of near-critical CO 2 and the dependence of solubility, transport and other properties on density allow the solvent quality to widely vary via simple pressure control without introducing a new component. Compared with liquid solvents, supercritical fluids are less viscous due to the greater free volume. Consequently, solutes diffuse more quickly. The surface tension of liquid CO 2 is only 1.5 mN/m at 25℃ and reaches to zero at the critical point, where liquid droplets are no longer formed. The low interfacial tension will allow CO 2 -based solvents to penetrate and wet nearly all features, no matter whether hydrophilic or hydrophobic. CO 2 can be evaporated at room temperature without remaining trapped liquid inside the pore structures, which could potentially affect the final product. Sc CO 2 is environmentally benign, nonflammable, nontoxic, leaves no liquid wastes, and is

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Reactions of Organosilanes with Silica Surfaces in Carbon Dioxide

Cited by 89 publications

References 44 publications

Surface chemistry of the iron tetraazamacrocycle on the aminopropyl‐modified surface of oxidized n‐Si(100) by AFM and XPS

Surface chemistry of the iron tetraazamacrocycle on the aminopropyl‐modified surface of oxidized n‐Si(100) by AFM and XPS

Synthesis of Mesoporous Organosilicate Films in Supercritical Carbon Dioxide

Supercritical CO2-based solvents in next generation microelectronics processing

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