| 摘要 |
PCT No. PCT/EP97/03406 Sec. 371 Date Feb. 26, 1998 Sec. 102(e) Date Feb. 26, 1998 PCT Filed Jun. 30, 1997 PCT Pub. No. WO98/00761 PCT Pub. Date Jan. 8, 1998A known projection aligner for integrated circuit fabrication, in which an integrated circuit pattern image is projected on a wafer, comprises an ArF excimer laser and an optical system composed of groups of quartz glass optical members made of synthetic quartz glass. To provide a projection aligner having optical properties, such as durability, optical transmittance and the like, which are not degraded over a long time of operation and the optical system can be constructed at a low cost as a whole, it is suggested that the optical system comprises a first quartz glass optical member group whose hydrogen molecule concentration is in the range between 1x1017 and 5x1018 molecules/cm3 and a third quartz glass optical member group whose hydrogen molecule concentration is in the range between 5x1018 to 5x1019 molecules/cm3.
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