Isolation of incompatible processes in a multi-station processing chamber

Abstract

A multi-station processing chamber in which incompatible processes are performed includes multiple pedestals positioned in wells with annular gaps around the pedestals. Showerheads located above the pedestals flow reactive gases over substrates located on the pedestals. The reactive gases are drawn through the annular gaps by a pressure gradient. The reactive gases are then pumped out of the wells through an exhaust port. The narrow annular gap permits little recirculation of the reactive gases one they are drawn into the wells. Moreover, the showerheads are flush with ceiling of the chamber and the wells contain smooth contours to minimize dead space in the chamber thereby reducing residence time of the reactive gases. An indexing plate is used to lift the substrates off the pedestals and to accurately position the substrates at the next processing station. In one embodiment a purge plate located on the ceiling of the chamber between the showerheads flows an inert gas, such as argon, to further assist in maintaining a separation between the reactive gases. Thus, while one process, such as a silane initiation is performed at one station, other stations may contemporaneously perform an incompatible process, such as a tungsten hexafluoride-silane nucleation process and hydrogen reduction, thereby increasing throughput.