| 摘要 |
PROBLEM TO BE SOLVED: To provide a beam delivery system which efficiently delivers laser beam of 200 nm or less. SOLUTION: A system is provided which delivers the laser beam of wavelength 200 nm or less from such laser as F2 laser or ArF laser to another housing, which eventually reaches a work piece, through a sealed enclosure which is air-tightly connected to the laser. The enclosure is exhausted, and then is filled with inert gas so that air, water, hydrocarbon or oxygen within the enclosure is fully discharged. Then, or instead of that, an inert gas flow is set and maintained in the enclosure while the laser is operated. The inert gas is preferred to be of high purity, for example, 99.5% or above, with 99.999% or above especially preferred. Nitrogen or rare gas is preferred. The enclosure is preferred to be sealed off using a transparent window against radiation of 200 nm or below so that no contaminant generated within the enclosure comes into the housing to contaminate the surface in the housing. The enclosure is preferred to be made of steel and/or copper, with the window preferred to be made of CaF2. |
