Patent ID: 8216391

Claim:
A substrate processing apparatus comprising: a processing unit having a holding mechanism configured to hold one substrate and a nozzle configured to supply a process liquid and process the substrate held by the holding mechanism; a processing bath capable of simultaneously accommodating a plurality of substrates, the processing bath storing a process liquid into which a substrate is immersed so as to be processed; an outer bath disposed on the processing bath and configured to collect a process liquid overflown from the processing bath; a circulation line disposed between the processing bath and outer bath so as to allow the process liquid overflown into the outer bath to return to the processing bath; and a transfer unit having a rotatable support arm and at least two holding parts supported by the support arm, the at least two holding parts being operable independently from each other with respect to the support arm, each holding part being able to hold one substrate, wherein the transfer unit is configured to simultaneously transfer vertically, by means of the at least two holding parts, into the processing bath one or more substrates whose number is less than the number of substrates that can be simultaneously accommodated in the processing bath, and are configured to transfer horizontally one substrate, by means of one of the at least two holding parts, into the processing unit, and wherein the substrate processing apparatus is configured to process one or more substrates with the use of at least one of the processing units and the processing bath.