Wednesday, November 7, 2007

Effects of Substrate Geometry on the Deposition Process in A Cvd Reactor

Yousef Sharifi, Chemical, Materials, and Biomolecular Engineering, University of Connecticut, 191 Auditorium Rd Unit 3222, Room 204, Storrs, CT 06268, Luke E. K. Achenie, Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Randolph Hall 133, Blacksburg, VA 24061, and Lorenz T. Biegler, Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213.

Chemical vapor deposition is a common technique for producing high quality semiconductors. Many parameters can play an important role in the efficiency of a CVD reactor, some of these parameters are: operating conditions, precursor concentration, and substrate geometry. While there has been much interest in investigating the effects of operating conditions or precursor concentrations on the deposition process, there has been less interest on the effect of substrate geometry on the deposition process. In the present work, we present a two dimensional CFD model in order to investigate the effects of substrate geometry on the deposition process. The non-isothermal model includes momentum, convection, diffusion, and thermal diffusion of species inside the CVD reactor. Various substrate geometries are created using Bezier curves, and the system of non-linear PDEs (describing the physics of the CVD reactor) are solved using finite element method. The physical properties of gaseous species are considered to be temperature dependent and are estimated using experimental correlations. The results indicate that certain substrate geometries can affect the flow pattern, create recirculation, and increase the deposition rate. Although, some of the geometries cannot be feasible in real experimental situations, this can give an insight to experimentalists to modify the reactor configuration in order to increase the deposition rate.