Patent ID: 6970770

Claim:
A cluster tool, comprising: a plurality of process chambers for performing process processing for objects to be processed; load lock chambers coupled to said process chambers respectively for transferring the objects to be processed to said process chambers; a loader module coupled to said load lock chambers for transferring the objects to be processed to said load lock chambers, the loader module being provided with a positioning mechanism for positioning the object to be processed; and a transfer control unit including a transfer period calculating unit for calculating a period for each of the load lock chambers to get ready to permit a next transfer thereto, when the object to be processed is transferred into any one of the load lock chambers, based on a processing period in the process chamber coupled to each of the load lock chambers and a processing period in each of the load lock chambers, and a selecting unit for selecting, as an object to be processed that is to be transferred next by the loader module, an object to be processed having the shortest period to get ready to be transferable, based on a calculation result of the transfer period calculating unit.