Substrate processing apparatus and method with processing unit selection based on usage rate and usage time

A substrate processing apparatus comprising:

• a carrier holding unit which holds a carrier that contains substrates;
• a plurality of processing units, each of which processes a substrate;
• a substrate transfer unit which transfers substrates between the carrier held by the carrier holding unit and the plurality of processing units;
• and
• a controller which controls the plurality of processing units and the substrate transfer unit, the controller including a processor and a storage device, the storage device storing a classification data indicative of a classification of the plurality of processing units into a plurality of groups and a group usage history data indicative of a usage history of each of the groups;
• wherein the controller is programmed such that the processor executes, when determining a processing unit that is to process a substrate, a group selection step of selecting one of the plurality of groups, a unit selection step of, after the group selection step, selecting one processing unit which belongs to the one group selected in the group selection step, a step of controlling the substrate transfer unit to carry a substrate to be processed into the processing unit selected in the unit selection step, a step of generating the group usage history data including a group usage rate data and a group final usage time data, and a step of registering the group usage history data thus generated into the storage device, and that the processor selects, in the group selection step, one of the groups based on the classification data and the group usage history data stored in the storage device, the group usage rate data being indicative of a group usage rate which is a rate of use for substrate processing of processing units which belong to each group, the group final usage time data being indicative of a group final usage time which is the time at which each group was used last for substrate processing,
• wherein the group selection step includes a step of selecting at least one group of which group usage rate is the lowest based on the group usage rate data stored in the storage device, and a step of selecting, when more than one group of which group usage rates are the lowest exist, a group of which group final usage time is the oldest based on the group final usage time data stored in the storage device.