Patent ID: 8670104

Claim:
A method used in an immersion lithography apparatus in which a wafer is exposed through an immersion liquid supplied via a nozzle member during a liquid immersion lithography process, the method comprising: placing a pad under a projection system for a cleanup process, the pad being different from the wafer and the cleanup process being performed separately from the immersion lithography process; and supplying, during the cleanup process, a cleaning liquid onto a surface of the pad via the nozzle member, the cleaning liquid being different from the immersion liquid, wherein: during the liquid immersion lithography process, a device pattern projection is performed, in which a device pattern image is projected by the projection system through the immersion liquid onto the wafer to fabricate semiconductor devices, during the cleanup process, the pad is disposed in place of the wafer and the pad is used without performing the device pattern projection, during the cleanup process, the pad is disposed directly vertically below the nozzle member from which the cleaning liquid is supplied onto the pad from above the pad, and the wafer is disposed directly vertically below the nozzle member from which the immersion liquid is supplied onto the wafer from above the wafer during the liquid immersion lithography process.