Abstract: An apparatus for etching one wafer while simultaneously pretreating or stripping another wafer. A module comprises a wafer etching chamber disposed within a larger chamber. The wafer etching chamber is adapted to etch a first wafer during the time that a second wafer is being pretreated in the larger chamber. When the first wafer is etched, it is transferred to the larger chamber and the pretreated second wafer is transferred to the etching chamber. During the time the second wafer is being etched the first wafer is stripped and removed from the larger chamber. A third wafer is introduced into the larger chamber for pretreating while the second wafer is being etched and the process repeated. Once a wafer enters the module for pretreating, etching and stripping, it is not exposed to the atmosphere until stripping is complete.