Characterization of showerhead performance at low pressure

The performance of showerheads used in semiconductor processing application s has been examined over a wide range of Knudsen number and Reynolds number . Both computational fluid dynamics and direct simulation Monte Carlo techn iques have been used to characterize the showerhead flow with the intent of developing correlations between the upstream velocity and the pressure dro p across the showerhead. Empirical correlations developed to account for en trance effects and rarefaction are also examined. Recommendations are made concerning boundary conditions and, when appropriate, correlations for give n pressures and flow rates. (C) 2000 American Vacuum Society. [S0734-211X(0 0)14306-9].