Patent ID: 8665415

Claim:
An exposure apparatus for exposing a substrate using an exposure beam, the apparatus comprising: a projection system, including an optical element, configured to project the exposure beam onto the substrate; an enclosure configured to enclose the projection system; and a cleaning mechanism configured to clean the optical element by irradiating the optical element with an ultraviolet beam under an environment in which oxygen is present within the enclosure, wherein the cleaning mechanism includes: a tubular member, including an exit window, configured to enclose at least part of an optical path between the optical element and a source that generates the ultraviolet beam; a driving mechanism configured to drive the tubular member between a position on an optical path of the exposure beam and a position outside the optical path of the exposure beam; and a regulating device configured to regulate an environment of an internal space of the tubular member so that a partial pressure of oxygen becomes lower in the internal space than in an external space of the tubular member, wherein the cleaning mechanism is configured to cause the ultraviolet beam that passes through the internal space of the tubular member, the environment of the internal space having been regulated by the regulating device, to be incident on the optical element via the exit window of the tubular member, the tubular member having been driven to the position on the optical path of the exposure beam by the driving mechanism.