A transfer chamber for a substrate processing tool includes a main body having side walls adapted to couple to at least one processing chamber and at least one load lock chamber. The main body houses at least a portion of a robot adapted to transport a substrate between the processing chamber and the load lock chamber. A lid couples to and seals a top of the main body of the transfer chamber. The transfer chamber also has a domed bottom adapted to couple to and to seal a bottom portion of the main body of the transfer chamber.