DESIGNING LOW-PRESSURE SYSTEMS WITH CONTINUUM MODELS

The predictions of a commercial Computational Fluid Dynamics (CFD-ACE) code were compared with experimental data to assess the validity of c ontinuum models at the low operating pressures typical of plasma etch and chemical vapor deposition reactors. Pressure data for nitrogen flo w (ranging from 100 to 500 seem) in a fully automated vacuum test cell , were collected at Lam Research Corporation for comparison [P. K. Shu fflebotham, T. J. Bartel, and B. Berney, J. Vac. Sci. Technol. B 13, 1 862 (1995)]. Both two- and three-dimensional model predictions of pres sure profiles at different sections of the test chamber were compared with data. Good agreement was observed between the measured and predic ted values of pressure over the range of flow rates investigated. Howe ver, as expected, better agreement was observed for the higher flow ra te (higher pressure) cases as compared to the lower flow rates. Furthe r improvements in model predictions are anticipated with the inclusion of slip boundary conditions at solid surfaces. (C) 1996 American Vacu um Society.