Silane thin films

Herlem, G., O. Segut, and A. Antoniou, 2008. Electrodeposition and characterization of silane thin films from 3-(aminopropyl)triethoxysilane. Surf. Coatings Technol 202 1437-42. 

In most cases, CVD reactions are activated thermally, but in some cases, notably in exothermic chemical transport reactions, the substrate temperature is held below that of the feed material to obtain deposition. Other means of activation are available (7), eg, deposition at lower substrate temperatures is obtained by electric-discharge plasma activation. In some cases, unique materials are produced by plasma-assisted CVD (PACVD), such as amorphous siHcon from silane where 10—35 mol % hydrogen remains bonded in the soHd deposit. Except for the problem of large amounts of energy consumption in its formation, this material is of interest for thin-film solar cells. Passivating films of Si02 or Si02 Si N deposited by PACVD are of interest in the semiconductor industry (see Semiconductors). 

The thermal decomposition of silanes in the presence of hydrogen into siUcon for production of ultrapure, semiconductor-grade siUcon has become an important art, known as the Siemens process (13). A variety of process parameters, which usually include the introduction of hydrogen, have been studied. Silane can be used to deposit siUcon at temperatures below 1000°C (14). Dichlorosilane deposits siUcon at 1000—1150°C (15,16). Ttichlorosilane has been reported as a source for siUcon deposition at >1150° C (17). Tribromosilane is ordinarily a source for siUcon deposition at 600—800°C (18). Thin-film deposition of siUcon metal from silane and disilane takes place at temperatures as low as 640°C, but results in amorphous hydrogenated siUcon (19). 

A thin film (typically 50-200 nm) is grown from solution to serve as a hybrid inorganic/organic gradient between the metal (oxide) surface and the organic primer or adhesive. XPS indicates that the surface is silane-rich and the... 

Glass-cloth-reinforced laminates, silane performance in, 22 702 Glass coatings, thin-film, 12 608—609 Glass components, 12 595t Glass compositions, 12 594t 13 387 bioactive, 12 611... 

Koh J, Ferlauto AS, Rovira PI, Wronski CR, Collins RW (1999) Evolutionary phase diagram for plasma enhanced chemical vapor deposition of silicon thin films from hydrogen diluted silane. Appl Phys Lett 75 2286-2289... 

Jeong et al. (2) prepared crosslinked copolymers consisting of methyl tri-methoxy silane and dipentaerythritol penta-/hexa-acrylate, which were effective as organic thin-film transistors and used in liquid-crystal display devices. 

Fig. 17.3 Temperature and flow-rate dependence of silicon thin-film growth for a silane CVD process. The left-hand panel shows the temperature dependence for a fixed inlet flow rate. The right-hand panel shows normalized growth rate as a function of inlet velocity for three different surface temperatures. The actual growth rate at U = 10 cm/s is stated parenthetically under the temperature call out.

Silane -for C VD [THIN FILMS - FILM FORMATION TECHNIQUES] (Vol 23) -hydndesm generation of [HYDRIDES] (Vol 13) -lithium hydride mprdn of [LITHIUM AND LITHIUM COMPOUNDS] (Vol 15) -use m silicon purification [SILICON AND SILICON ALLOYS - PURE SILICON] (Vol 21)... 

These conclusions were supported by results obtained from angle-resolved XPS. The band near 932.4 eV in the Cu(2pV2) photoelectron spectrum of the mirror coated with y-APS increased in intensity relative to that near 934.9 eV when the take-off angle was increased from 15° to 75°. Similarly, the band near 336.8 eV in the Auger spectrum also increased in intensity relative to that near 340.0 eV. Such behavior would be expected if the bands near 932.4 eV in the photoelectron spectrum and near 336.8 eV in the Auger spectrum were related to an oxide that was covered by a thin film of silane. 

However, a second component shifted to higher binding energy was observed for thin films of the compound adsorbed onto aluminum that had been cleaned by ion bombardment and then exposed to oxygen. Finally, Linde [18] has suggested that polyamic acids of pyromellitic dianhydride and oxydianiline do not react with films formed by y-APS adsorbed onto metal substrates such as aluminum and chromium because the silane is adsorbed through the amino groups. 

In this paper we report on TOFSIMS and XPS analyses of thick and thin films of SAAPS on zinc in order to demonstrate the effect of film thickness. We also present some TOFSIMS results obtained with films of y-APS on mild steel in which the effects of the cleaning process of the substrate and the pH of the silane solution are demonstrated. 

The silane films were prepared by dipping the substrates in 1 vol% aqueous solutions for 30-60 s. Some were then blown dry with nitrogen and introduced into the SIMS instrument within 2 h. In general, relatively thick films were prepared by dipping for 60 s, followed by dripping for 60 s. The films were then dried in air and not blown dry. Thin films were prepared by dipping for 30 s after which they were blown dry immediately. Some films were heated for 30 min at 150°C in air prior to analysis. 

The purpose of the experiments described below was to study the effect of the pretreatment of the substrate and of the pH of the silane solution on the structure of the film. Only thin films, as described in the previous section for SAAPS on zinc, were prepared and analyzed. Heating experiments were not performed, but will be reported in a forthcoming paper. All spectra were run under conditions of high mass resolution. 

The aminosilane coupling agent 3-aminopropyltriethoxysilane or y-amino-propyltriethoxy silane—also abbreviated as 3-APS, y-APS, APS or A1100 (Union Carbide)—is widely used to promote adhesion between polyimide thin films and mineral surfaces such as native-oxide silica, alumina and various glass ceramics [1, 2]. The structure of APS and the hydrolysis reaction sire shown in Fig. 1. Typically, dilute aqueous solutions of 0.1 vol% or approximately 0.080 wt % are employed to prime the mineral surface. The mechanism for the interaction of the bifunctional aminosilane with the mineral surface is the subject of much speculation, although it is conjectured by Linde and Gleason [3] that the amine end initially forms an electrostatic bond with surface hydroxyls. Subsequently, possibly as the result of elevated temperatures, the silanol end of the molecule proceeds to form a siloxane-like bond with the surface and the amine... 

Chemical Reaction Mechanisms and Kinetics. CVD chemistry is complex, involving both gas-phase and surface reactions. The role of gas-phase reactions expands with increasing temperature and partial pressure of the reactants. At high reactant concentrations, gas-phase reactions may eventually lead to gas-phase nucleation that is detrimental to thin-film growth. The initial steps of gas-phase nucleation are not understood for CVD systems, not even for the nucleation of Si from silane, which has a potential application in bulk Si production (97). In addition to producing film precursors, gas-phase reactions can have adverse effects by forming species that are potential impurity sources. 

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