Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-19T01:45:56.250Z Has data issue: false hasContentIssue false
  • English
  • Français

Calculation of Transport-Shifted CVD Phase Diagrams

Published online by Cambridge University Press:  21 February 2011

Daniel E. Rosner  and
Joshua Collins
Daniel E. Rosner
Affiliation:
Yale University, Department of Chemical Engineering, High Temperature Chemical Reaction Engineering Laboratory, New Haven CT 06520-2159, USA.
Joshua Collins
Affiliation:
Yale University, Department of Chemical Engineering, High Temperature Chemical Reaction Engineering Laboratory, New Haven CT 06520-2159, USA.
Get access

Abstract

A non-iterative method is presented for constructing CVD phase diagrams which include the systematic effects of chemical element segregation in mass-transfer controlled flow reactors. Element segregation is shown to substantially shift predicted deposit phase boundaries when the vapor/deposit interface equilibrium is calculated using the local element fractions instead of the feed gas elemental composition, as is usually done. The mass transfer analysis developed here accounts for both Fick and Soret multicomponent diffusion acting across a non-isothermal boundary layer. The gas phase is assumed to be chemically frozen, with local thermochemical equilibrium imposed only at the vapor/deposit interface (as in a cold wall reactor with a hot substrate). As a specific example, this model is applied to the chemical vapor deposition of titanium diboride from TiCl4(g), BC13(g) and H2(g) in an Ar(g) carrier gas for ceramic composite material applications. These calculations, which account for boron and titanium transport via 17 chemical species, are illustrated for a long cylindrical reactor with a resistively heated coaxial fiber deposition substrate and coaxial annular flow. However, the method presented here is general in that both the chemical system and CVD reactor geometry can be changed to any other system of interest, provided: i) adequate themochemical and thermophysical data are available, ii) the deposition rate is vapor transport controlled, and iii) convective-diffusion heat and mass transfer coefficients are estimable.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 168 , 1989 , 43
Copyright
Copyright © Materials Research Society 1990

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

a

Professor of Chemical Engineering and Director, Yale HTCRE Laboratory

b

Graduate Research Assistant and NASA GSRP Fellow, Yale HTCRE Laboratory

References

1.Spear, K.E., in CVD 7th Int Conf, Eds Sedgwick, T.O. and Lydtin, H. (Electrochem. Soc., NJ 1979) pp 1–16.Google Scholar
2.Spear, K.E., in CVD 9th Int. Conf, Eds. Robinson, McD.et al. (Electrochem. Soc., NJ 1984) pp 81–97.Google Scholar
3.Besmann, T.M. and Spear, K.E., J. Electrochem. Soc. 124 (5), 789 (1977); 124 (5) 790(E) (1977).Google Scholar
4.Rosner, D.E. and Nagarajan, R., Chem. Eng..Sci. 40 (2), 177 (1985).Google Scholar
5.Rosner, D.E., Nagarajan, R., Kori, M., and Gokoglu, S.A., in CVD 10th Int Cont, Ed Cullen, G.W. (Electrochem. Soc., NJ 1987) pp 61–80.Google Scholar
6.Gokoglu, S.A., J. Electrochem. Soc. 135 (6), 1562 (1988).Google Scholar
7.Rosner, D.E., Heat, J. and Mass Trans 9, 1233 (1966).Google Scholar
8.Rosner, D.E., in Symp. on High Temp. Lamp Modeling, (Electrochem Soc., NJ 1988) pp 111–138.Google Scholar
9.Rosner, D.E., PhysicoChemical Hydrodynamics (Pergamon) 1, 159 (1980).Google Scholar
10.Rosner, D.E. and Keyes, D.E., NASA Contractor Report 185122 (July, 1989).Google Scholar
11.Rosner, D.E. et al., Comb. Sci. Tech. 20 87 (1979).Google Scholar
12.Gokoglu, S.A. and Rosner, D.E., NASA Contractor Report 168322 (January,1984).Google Scholar
13.Rosner, D.E., Transport Processes in Chemically Reacting Flow Systems, (Butterworths Publishers, Boston, 1986).Google Scholar
14.Gordon, S. and McBride, B.J., NASA Report SP-273 (1976).Google Scholar
15.Svehla, R.A., NASA Technical Report R-132 (1962).Google Scholar
16.Bzowski, J., Mason, E.A., and Kestin, J., Int. J. Thermophys. 9 (1), 131 (1988).Google Scholar