System for rinsing optical unit used in semiconductor lithography to prevent contamination during transport

摘要

A projection objective lens (1) has three sections (2,3,4) the outer surfaces of which are to be protected from contamination. A pump (5) delivers scavenging gas (air or a very pure inert gas) to a filter (6) in the form of an active carbon filter or catalytic purifier. Valves (7) (forward flow) and (8) (reverse flow) control the flow so that the maximum pressure above atmosphere is, e.g. 10 mbar. Valves (9,10,11) control the flow to the individual section of the lens.