Abstract: A substrate processing apparatus having a plurality of substrate processing modules connected to a substrate transport. The substrate transport has a housing and a substrate transport mechanism. The housing forms a substantially closed main transport chamber with doorways into the main transport chamber for the substrate processing modules. The transport mechanism has a substrate holder movably located in the transport chamber. The housing includes a front end extension that is connected to load locks. The front end extension has an aligner, a cooler, and a buffer directly connected to the housing and located in the front end extension in part of the main transport chamber.