Vapor phase silanizations

Bauer,R., Smulders,R, Geus,E., vanderPut, J., and Schoomman, J., Laser Vapor Phase Synthesis of Submicron Silicon and Silicon Nitride Powders from Halogenated Silanes, Ceram. Eng. Sci. Proc., 9(7-8) 949-956(1988)... 

Many silane coupling agents can be applied to substrates by volatilization in an enclosed chamber under heat or vacuum. In this approach, the substrate is placed within the chamber in a fashion to allow for vapor phase molecules to access all areas that are to be derivatized. This method is commonly used for silanizing glass slides or substrates that are difficult to suspend in a silane solution. Slides are often placed in racks within the chamber and all surfaces get modified... 

Despite the potential for atomic-scale manipulation of interfaces displayed by molecular-beam epitaxial growth, a majority of the vapor-phase growth of silicon is accomplished by the reaction of silane with silicon substrates This... 

A range of procedures have been described for the silanization of glass, including approaches employing both elevated and room-temperature organic phase, aqueous phase, vapor phase, and chemical vapor deposition of the silane. However, little has been published with regard to the rehability and... 

The basic principle behind the silane overpressure annealing process is as follows. When the SiC wafer is annealed at high temperatures (> 1,600°C), Si atoms on the surface of the SiC wafer may be exchanged with Si atoms provided by the silane gas in the vapor phase. Chemical process calculations were performed for various pressures and silane flow rates as a function of temperature. These calculations,... 

Figure 10 Dark and photocurrents with FeCp 70 redox couple before and after interfacial passivation, (a) Effect of blocking recombination at the Sn02 surface, reaction (5) (Fig. 9a), by electropolymerization of PPO. (b) Effect of blocking recombination at both the Sn02 and Ti02 surfaces, reactions (4) and (5) (Fig. 9b), by vapor-phase silane treatment without PPO. (Data from Ref. 49.)...

TFSA satisfies all these requirements for hydrophilic silicone surfaces. Using silica as a model for extensively oxidized silicone surfaces, we showed that silylation with vapor phase TFSA took place at room temperature under scrupulously dry conditions. In contrast, others have found for the more conventional silylating agents, the methylchlorosilanes and the methylmethoxy-silanes, that no reaction occurred at temperature below 200°C under similar dry conditions [38]. 

In Fig. 7, the difference in C Is ESCA spectra for vapor phase HMDS vs. liquid phase silane treatments is provided. The C Is XPS spectral changes are... 

The double promoter process involves the successive application of liquid promoter solutions of vinyltrichlorosilane (VTS) and 3-chloropropyltrimethoxy-silane followed by successive cure cycles in dry N2 at 90°C after each application and before photoresist application. The double promoter process evolved because it was felt that the silane reaction with the SiOH surface groups of low temperature oxides was incomplete for a single promoter application, and because vapor silane equipment did not exist at that time. Interestingly, a double HMDS liquid promoter process failed to yield adequate adhesion as well. Later in time, the successful but somewhat complex double promoter process was replaced by the vapor phase HMDS process in the Star 1000 (or 2000) then superior resist image adhesion was obtained on all four oxide substrates with all the photoresists tested. Before the advent of the HMDS vapor priming in standalone or wafer track equipment module chambers, liquid priming solutions were widely used, especially in development areas. 

Although no adhesion failures were observed for virgin aluminum substrates as found for gold with a variety of liquid silanes, VTS and vapor-phase HMDS-treated wafers were analyzed via ESCA to determine whether surface changes occurred with these treatments. For VTS-treated substrates, a dramatic 20-fold increase in the Si/Al ratio occurred with a concurrent decrease in carbon surface... 

Dehydrodimerization. On excitation with a mercury vapor lamp, mercury is converted to an excited state, Hg, which can convert a C—H bond into a carbon radical and a hydrogen atom. This process can result in dehydrodimerization, which has been known for some time, but which has not been synthetically useful because of low yields when carried out in solution. Brown and Crabtree1 have shown that this reaction can be synthetically useful when carried out in the vapor phase, in which the reaction is much faster than in a liquid phase, and in which very high selectivities are attainable. Secondary C—H bonds are cleaved more readily than primary ones, and tertiary C—H bonds are cleaved the most readily. Isobutane is dimerized exclusively to 2,2,3,3-tetramethylbutane. This dehydrodimerization is also applicable to alcohols, ethers, and silanes. Cross-dehydrodimerization is also possible, and is a useful synthetic reaction. 

Surface Modification with Chlorosilanes. Chlorosilanes are volatile and very sensitive to the presence of trace amounts of water. Vapor-phase silanization reactions with rigorous control of the absence of water show that Cl SiMe4-n-type chlorosilanes react with aerosil (nonporous microparticulate silica) as... 

Gas/vapor phase modifications. Many inorganic membrane materials display functional groups that have chemical affinity to selected chemical agents. A well known example is a gamma-alumina membrane which has hydroxyl groups on the surfaces of the alumina crystallites. These hydroxyl groups present on the pore walls and the macroscopic surface of the membrane can act as the reactive sites for modifications of the pore structure with a chemical agent such as the diversified family of silane compounds (chloro- or alkoxy>silanes). 

Byproduct adsorption and/or reaction is an ubiquitous feature in vapor phase silanizations. We include the possibility of reaction because of the following experiments. Exposure of clean pellet to byproducts (HC1, CH3OH, or NH3) generates the respective absorption bands cited above, but it also causes gross attenuation of the 0-H bands. Such a result is consistent with equation 2 ... 

An interesting question is whether these results are characteristic of vapor-phase silanizations or whether they extend to liquid-phase reaction conditions. Silanizations are most commonly performed in solutions. We are pursuing this question currently. 

Abstract. The design and synthesis of new molecular synthons for vapor-phase self-assembled nanodieletrics and silane crosslinkers for crosslinked polymer blend dielectrics is described. These dielectric films exhibit excellent dielectric properties with tunable thicknesses and capacitance values. These new gate dielectric materials are integrated into thin-film transistors based both p- and n-type organic semiconductors. 

Dichlorocarbene. This silane decomposes in the vapor phase at 120-140° to liberate dichlorocarbene and SiF3Cl. Added olefins are converted into gem-dichlorocyclopropanes in 85-95% yields. The reaction is stereospecific with cis- and tra/is-2-butene. ... 

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