Apparatus and method for processing substrate

The inventive concept provides an apparatus and method for processing a substrate. The apparatus includes an index module and a processing module that is disposed adjacent to the index module and that processes the substrate. The index module includes one or more load ports, on each of which a carrier having the substrate received therein is placed, a side storage that stores the substrate subjected to a process in the processing module and removes fumes on the substrate, and a transfer frame including an index robot that transfers the substrate between the carrier placed on the load port, the side storage, and the processing module. The side storage includes a housing having an interior space, a partitioning unit that partitions the interior space into a plurality of receiving spaces independent of one another, and an exhaust unit that independently and separately evacuates the plurality of receiving spaces.