Bottom purge for semiconductor processing system

A substrate processing system comprising:

• a plurality of processing regions;
• a transfer region housing defining a transfer region fluidly coupled with the plurality of processing regions;
• a plurality of substrate supports, each substrate support of the plurality of substrate supports vertically translatable between the transfer region and an associated processing region of the plurality of processing regions;
• a plurality of purge channels defined through the transfer region housing, a number of purge channels of the plurality of purge channels equal to a number of substrate supports of the plurality of substrate supports;
• and
• a transfer apparatus comprising:
• a rotatable shaft extending through the transfer region housing, and
• an end effector coupled with the rotatable shaft, wherein the end effector includes a central hub defining a central aperture fluidly coupled with a purge source, wherein the central aperture extends through a top surface of the central hub, and wherein the end effector further includes a plurality of arms having a number of arms equal to a number of substrate supports of the plurality of substrate supports.