Patent ID: 7576833
Filing Date: 2009-08-18
Classification: G03F

Abstract:
1. An apparatus, comprising: a substrate holder which holds a substrate having an imaging surface; a projection optical system having a last optical element, during an exposure operation the projection optical system projecting an image onto a target imaging area on the imaging surface of the substrate through an immersion liquid filled in a space between the imaging surface of the substrate and the last optical element; an immersion element which maintains the immersion liquid in the space between the imaging surface of the substrate and the last optical element during the exposure operation, the immersion element having a gas inlet for providing gas, the gas being provided from the gas inlet into a gap between the immersion element and an object facing the immersion element; a liquid outlet in the immersion element, the immersion liquid being removed from the gap through the liquid outlet; and a first porous region provided adjacent the gas inlet of the immersion element, the first porous region allowing the immersion liquid to pass therethrough from the gap while substantially preventing gas from passing therethrough from the gap, the first porous region being located radially outwardly of the liquid outlet relative to the space, the gas inlet being located radially outwardly of the first porous region relative to the space.