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 continuum models at the low operating pressures typical of plasma etch and chemical vapor deposition reactors. Pressure data for nitrogen flow (ranging from 100 to 500 sccm) in a fully automated vacuum test cell, were collected at Lam Research Corporation for comparison [P. K. Shufflebotham, T. J. Bartel, and B. Berney, J. Vac. Sci. Technol. B 13, 1862 (1995)]. Both two‐ and three‐dimensional model predictions of pressure profiles at different sections of the test chamber were compared with data. Good agreement was observed between the measured and predicted values of pressure over the range of flow rates investigated. However, as expected, better agreement was observed for the higher flow rate (higher pressure) cases as compared to the lower flow rates. Further improvements in model predictions are anticipated with the inclusion of slip boundary conditions at solid su...