| 摘要 |
PURPOSE:To obtain gas of long life, by a method wherein, when the gas is filled in the laser tube of an excimer laser equipment, in advance of that, the amount of residual impurity gas is decreased by vacuumizing the inside of said laser tube to a high degree of vacuum. CONSTITUTION:When the ultimate degree of vacuum of a laser tube 2 before gas G is filled is made an order of 10<-3>Torr, and KrF laser is made to oscillate with a repetition rate of 100Hz, the shot number till the average output of the laser is decreased by 50% is about 3X10<6> shots, which is nearly one digit larger than prior values. Further, the amount of residual gas in the laser tube 2 decreases, so that the number of passivations till the laser oscillation is stabilized can also be reduced. In order to vacuumize the inside of the laser tube 2 to an order of the degree of vacuum of 10<-3>Torr, it is desirable to install a vacuum pump 26 having high ultimate degree of vacuum such as an oil diffusion pump, a molecular turbopump and a cryopump, in the pre-stage of a rotary pump 16. |
