Gas curtain type immersion lithography tool using porous material for fluid removal

摘要

A gas curtain type immersion lithography apparatus has a fluid removing porous region adjacent the gas inlet to prevent evaporative cooling. The apparatus includes a substrate holder which holds a substrate having an imaging surface and a projection optical system having a last optical element. The projection optical system projects an image onto a target imaging area on the substrate through an immersion fluid filled in a gap between the imaging surface of the substrate and the last optical element. An immersion element maintains the immersion fluid in the gap. Gas is provided through an inlet into the gap. A porous region is provided adjacent the gas inlet. Immersion fluid that collects near the gas inlet is removed by the porous region.