a method and apparatus to eliminate contaminants in a lithography process for fabrication of integrated circuit devices . the method includes depositing a photoresist material on surface of a semiconductor substrate . a purge gas flow is provided proximate to an optical element to prevent a vapor from the exposed photoresist material from coming into contact with the optical element . in one embodiment , the purge gas flows into a perforated and open ended enclosure in which the optical element is provided in the form of a lens . one open end of the enclosure is coupled to the lens and the other open end is positioned above the surface of the semiconductor substrate . perforation of the enclosure facilitates movement of purge gas thereto , eliminating contact with the vapor from the developed resist and unwanted deposition of a solid contamination on the lens .