Tantalum chemical vapor deposition

Chemical vapor deposition processes are complex. Chemical thermodynamics, mass transfer, reaction kinetics and crystal growth all play important roles. Equilibrium thermodynamic analysis is the first step in understanding any CVD process. Thermodynamic calculations are useful in predicting limiting deposition rates and condensed phases in the systems which can deposit under the limiting equilibrium state. These calculations are made for CVD of titanium - - and tantalum diborides, but in dynamic CVD systems equilibrium is rarely achieved and kinetic factors often govern the deposition rate behavior. 

The other platform is dielectrics, for example, silicon dioxide, silicon nitride, silicon oxynitride, tantalum pentoxide, and titanium dioxide. They can be deposited by various methods, such as plasma-enhanced chemical vapor deposition, thermal evaporation, electron-beam evaporation, and sputtering. There are a number of dielectrics with refractive indices ranging from 1.45 to 2.4, facilitating diverse waveguide designs to satisfy different specification. Dielectrics have two other... 

Wieczorek, C., Chemical vapor deposition of tantalum disilicide. Thin... 

Reynolds, G.J., Low-pressure chemical vapor deposition of tantalum sili-... 

Subsequent preliminary comparative studies of the behavior of an SiC based layer on Ta, Mo, Ti and steel substrates showed that better mechanical stability was obtained with a coating deposited on tantalum. This element was consequently considered to make PFCVD deposit/interlayer/steel stacks. Tantalum can be produced by physical vapor deposition (PVD), at variable thickness, with reproducible morphology. Note that preparation by chemical vapor deposition with or without plasma assistance (CVD or PECVD) is possible at low temperature but would require an optimization study in order to be compatible with the deposition conditions of the silicon carbide layer, the aim being to increase the mechanical stability. 

For carbide modification of graphite tubes (for a recent review see Refs. [183, 184], use is made of physical and chemical vapor deposition with metals such as Ta, W, Zr, etc., which leads to the formation of MC-coated graphite tubes or platforms. A solid layer of tantalum or niobium carbide can also be obtained as a result of treatment of the graphite furnace with large quantities of pure salts or a suspension of the element or its oxide in water however, this can lead to tubes with shorter lifetimes. Alternatively, the surface may be treated with aqueous [e.g. of Na2WC>4, (NH CriCb or ZrOCh] or alcoholic solutions of the salts of the elements mentioned. 

Tantalum, which is used for a number of applications, was recently made into a porous material that could be used for bone reconstruction. The porous structure is made by depositing the metal onto a vitreous carbon scaffold using chemical vapor deposition/infiltration techniques. Its low stmctural density means that its stiffness (2.5-4 GPa) is closer to that of natural bone than the solid metal, and the porosity means that bone can fully integrate into the stmcture. forming an excellent bond. " ... 

Fitzer, E. Kehr, D. (1973) Processing studies of the chemical vapor deposition of niobium and tantalum. In Proceedings 4th International Conference CVD, pp. 144-146. 

Spitz, J. Chevallier, J. (1975) Comparative study of tantalum deposition by chemical vapor deposition and electron beam vacuum evaporation. In Proceedings 5th International Conference CVD, pp. 204-216. 

Hydrogen reduction of trichlorosUane or thermal decomposition or chemical vapor deposition (CVD). In this new and modern method, after distillation, the refined ultrapure trichlorosilane, SiHCl, is mixed with hydrogen gas and the gas mixture fed into a reaction-heated vessel. A heating filament made of pure tantalum is heated by an electric current. The resulting purified polycrystaUine silicon is deposited and grown on the surface of cm electrically heated tantalum-metal hollow wick according to the following reaction ... 

Spitz J. and Chevalier J., Comparative Study of Tantalum by Chemical Vapor Deposition and Electron Beam Vacuum Evaporation, (1975) 5th international conference on CVD... 

Kukli K., Ritala M., Leskelae M. Atomic layer deposition and chemical vapor deposition of tantalum oxide by successive and simultaneous pulsing of tantalum ethoxide and tantalum chloride. Chem. Mater. 2000 12 1914-1920... 

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