Dependency of Purge Duration of an Atomic Layer Deposition Process on the Outlet Size of a Viscous Flow Reactor

For a better understanding the effects of size and number of outlet manifolds of a viscous flow reactor on the purge duration in an atomic layer deposition (ALD) process, three-dimensional multicomponent gas transports inside the reactors with different outlet configurations are investigated through reactor scale simulations.The simulations are performed at a fixed operating pressure and temperature of 10 torr (1333 Pa) and 300 °C, respectively.Several reactor designs are considered and results are compared with a reactor that is used as the base of comparison.Because of low values of Knudsen numbers (less than 0.01) inside the reactors, applying the continuum flow assumption with no-slip boundary conditions is accurate to simulate the multicomponent flow.The Navier-Stokes and species transport equations are discretized through the finite volume method to simulate transient, laminar, and multicomponent flows.It is found that the purge durations are mainly dictated by the outlet velocity such that as long as the average outlet velocity remains the same, the purge times are almost similar among all reactors with different number of outlets.Also, results suggest that there is a threshold purge velocity such that beyond this value the purge times become independent from the outlet velocity.