Patent ID: 7378669
Filing Date: 2008-05-27
Classification: G03F

Abstract:
1. A lithographic projection apparatus comprising: a beam path for a beam of radiation, the beam path comprising a radiation system for providing the beam of radiation, a projection system, a support structure for supporting a patterning device and a substrate holder for holding a substrate, the projection system projecting the beam of radiation patterned by the patterning device onto a target portion on the substrate; a chamber that comprises at least part of the beam path and in which at least part of the radiation system, the projection system, the support structure, the substrate holder, or any combination thereof, is exposed to an atmosphere in said chamber; a purge gas supply subsystem coupled to said chamber for supplying a flow of purge gas to said chamber, the purge gas supply subsystem comprising a valve; and a control unit coupled to the radiation system and the purge gas supply subsystem, and constructed and arranged to switch the purge gas supply subsystem between at least two different modes of operation, the control unit being configured to control the valve of the purge gas supply subsystem to supply mutually different respective non-zero flow rates of the purge gas to the chamber and to control operation of the radiation system in the different modes of operation.