Lithographic apparatus and device manufacturing method

摘要

A projection lens (PL) projects patterned light beam with respect to a wafer (W) mounted on a stage (WSH). A controller controls a flow restrictor to restrict the rate of flow of purge gas with respect to a compartment surrounding the main portion of the projection lens, when the contamination level within the compartment is below threshold level. An independent claim is also included for device manufacturing method.