LITHOGRAPHY PROJECTION APPARATUS

PROBLEM TO BE SOLVED: To improve the lithography performance of an apparatus having a liquid that fills the space between a final element of a projection system and a substrate. SOLUTION: A lithographic apparatus and a device manufacturing method make use of a high-refractive index liquid, confined in a reservoir 13, at least partly filling a lithography field between a final element of a projection lens and the substrate. Bubbles forming in the liquid resulting from dissolved atmospheric gases or the gas discharge from an apparatus element exposed to the liquid are detected and removed so that they do not interfere with the exposure, to cause burning defects on the substrate. The detection can be carried out, by measuring the frequency dependence of ultrasonic attenuation in the liquid and the removal of bubbles can be implemented by: degassing and pressurizing the liquid; isolating the liquid from the atmosphere; supplying a continuous flow of liquid through the lithography field using liquids of low surface tension; and further, phase-shifting the ultrasonic standing-wave nodes. COPYRIGHT: (C)2011,JPO&INPIT