Chemical vapor deposition processing

In chemical vapor deposition processing, the principal source of residual stress is from a coefficient of expansion mismatch. One of the principal criteria for CVD processing is the matching of the coefficient of expansions of the film and substrate, which limits the possible film—substrate combinations that can be used. 

Tertiary stibines have been widely employed as ligands in a variety of transition metal complexes (99), and they appear to have numerous uses in synthetic organic chemistry (66), eg, for the olefination of carbonyl compounds (100). They have also been used for the formation of semiconductors by the metal—organic chemical vapor deposition process (101), as catalysts or cocatalysts for a number of polymerization reactions (102), as ingredients of light-sensitive substances (103), and for many other industrial purposes. 

Many attempts have been made to synthesi2e cubic BN at low pressures by some sort of chemical vapor deposition process in analogy with the low pressure deposition of diamond from methane in the presence of H atoms (see Diamond, synthetic). However, the amounts of cubic BN produced in this fashion in 1991 were miniscule, and were at best thin layers only a few do2en atoms thick (12). 

Diamonds also occur in meteorites, probably as a result of high pressures produced dynamically by impact (10,11). The shock or explosive mode of synthesis is a viable process for fine diamond powders of both the cubic and hexagonal (lonsdaleite) polymorphs (12) naturally or otherwise. Some diamonds in space appear to have formed by processes more closely related to the low pressure chemical vapor deposition processes described later (see... 

Naimpally, A., A Study of the Annealing Processes for Doped Glasses Deposited by the Chemical Vapor Deposition Process, Y4MPE J., pp. 24-5 (Sept/Oct 1988)... 

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. 

Metal and polysilicon films are formed by a chemical-vapor deposition process using organometallic gases that react at the surface of the IC structure. Various metal silicide films may also be deposited in this manner by reaction with the surface of the silicon wafer to form metal silicides. Glass and pol3uner films are deposited or spin cast or both, as are photoresist films (those of a photosensitive material). This process is accomplished by applying a liquid polymer onto a rapidly rotating wafer. The exact method used varies from manufacturer to manufacturer and usually remains proprietary. 

Wang HB, Meng GY, and Peng DK. Aerosol and plasma assisted chemical vapor deposition process for multi-component oxide La08Sr02MnO3 thin film. Thin Solid Films 2000 368 275-278. 

In Section 3.4.2, we introdnced the concept of chemical vapor infiltration, CVI, in which a chemical vapor deposition process is carried out in a porous preform to create a reinforced matrix material. In that section we also described the relative competition between the kinetic and transport processes in this processing technique. In this section we elaborate npon some of the common materials used in CVI processing, and we briefly describe two related processing techniques sol infiltration and polymer infiltration. 

Certain numerical algorithms can benefit from the equation in a form that has the dependent variable Ft directly in the diffusive terms on the right-hand side. Moreover, for flows that have relatively small mean-molecular-weight gradients, the second term may be negligible. Examples of this situation would be if there is an inert carrier gas that dominates the species composition. It is not unusual in chemical-vapor-deposition processes for... 

The rotating disk is a configuration that was first identified and analyzed by Von Karman [418], and studied extensively for its similarity reduction of the Navier-Stokes equations [65,374], It was later recognized for its value in chemical vapor deposition processes... 

Fig. 17.1 Illustration of a stagnation-flow chemical-vapor deposition process.

In addition to the catalytic-ignition problem, this approach has been successfully implemented on opposed-flow strained-flame simulations with the inlet flow oscillating at high frequency [193]. It has also been used to model transient chemical-vapor deposition processes where the inlet flow is varies under a real-time control algorithm [324]. Although it is unlikely that a practical process-control system would be designed to induce extremely fast transients, it is important that the simulation remain stable to any potential controller command. 

C.R. Kleijn. Chemical Vapor Deposition Processes. In M. Meyyappan, editor, Computational Modeling in Semiconductor Processing, pages 97-216. Artech House, Boston, 1995. 

L.L. Raja, R.J. Kee, R. Serban, and L.R. Petzold. A Computational Algorithm for Dynamic Optimization of Chemical Vapor Deposition Processes in Stagnation Flow Reactors. J. Electrochem. Soc., 147 2718-2726,2000. 

Bismuth is an important element in many of the new high-temperature, oxide superconductors and in a variety of heterogeneous mixed oxide catalysts. Some of the methods employed in the preparation of these materials, namely sol-gel and chemical vapor deposition processes, require bismuth alkoxides as precursors and a number of papers on these compounds have recently been published.1 One synthetic route to bismuth alkoxides, which avoids the more commonly used trihalide starting materials and the often troublesome separation of alkali metal halides, involves the reaction between a bismuth amide and an alcohol according to the following equation ... 

The determination of specific phosphorus compounds in thin films is important. Only through wet chemical analysis was it possible to first discover the presence and then to accurately measure the quantities of P2Os, P203, and phosphine found in plasma, plasma-enhanced, LPO-LTO (low-pressure oxide-low-temperature oxide), and CVD (chemical vapor deposition) processes (3). Methods such as X-ray or FTIR spectroscopy would have seen all phosphorus atoms and would have characterized them as totally useful phosphorus. In plasma and plasma-enhanced CVD films, phosphine is totally useless in doping processes. 

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