A cluster tool architecture and method are provided for
processing substrates by
exposure to a process environment, including a
reactive gas, such as
sulfur trioxide, as well as prior and subsequent treatments thereto. The cluster tool architecture comprises: (a) an atmospheric
processing area, maintained at
atmospheric pressure or higher; (b) cassette means for introducing a plurality of the substrates into the atmospheric
processing area; (c) at least one process
station in the atmospheric processing area; (d) an enclosed vacuum processing area, maintained at a
vacuum pressure; (e) a first buffer
station between the atmospheric processing area and the enclosed vacuum processing area; (f) at least one process
station in the enclosed vacuum processing area isolated from the enclosed vacuum processing area by an
isolation valve for exposing the substrates to the process environment; (g) a second buffer station between the atmospheric processing area and the enclosed vacuum processing area; (h) an atmospheric transfer arm in the atmospheric processing area for transferring the substrates from the cassette means between one of the buffer stations and at least one process station in the atmospheric processing area and then to the cassette means; and (i) a vacuum transfer arm in the enclosed vacuum processing area for transferring the substrates from one of the buffer stations to one of the vacuum process stations in the enclosed vacuum processing area and from that vacuum process station in the enclosed vacuum processing area to the buffer station, wherein both buffer stations are equally accessible to both the atmospheric transfer arm and the vacuum transfer arm. The cluster tool architecture integrates atmospheric or
high pressure processing with vacuum processing. Since integration allows
random access, there is a freedom of
programming process flow. The architecture allows re-entry of substrates, so that process steps can be repeated at any time, and it allows substrates to be replaced back into original cassette after process is complete.