Abstract: A method and apparatus for cleaning the inside of an immersion lithographic apparatus is disclosed. In particular, a liquid supply system of the lithographic apparatus may be used to introduce a cleaning fluid into a space between the projection system and the substrate table of the lithographic apparatus. Additionally or alternatively, a cleaning device may be provided on the substrate table and an ultrasonic emitter may be provided to create an ultrasonic cleaning liquid.

Abstract: A method for correcting an exposure parameter of an immersion lithographic apparatus is provided. In the method, an exposure parameter is measured using a measuring beam projected through a liquid between the projection system and a substrate table of the immersion lithographic apparatus and offset is determined based on a change of a physical property impacting a measurement made using the measuring beam to at least partly correct the measured exposure parameter. Also, there is provided an apparatus and method to measure a height of an optical element connected to liquid between the projection system and the substrate table in the immersion lithographic apparatus.

Abstract: A porous member is used in a liquid removal system of an immersion lithographic projection apparatus to smooth uneven flows. A pressure differential across the porous member may be maintained at below the bubble point of the porous member so that a single-phase liquid flow is obtained. Alternatively, the porous member may be used to reduce unevenness in a two-phase flow.