Whitman Breed Abbott & Morgan LLP
Projection aligner for integrated circuit fabrication
 A 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 1.times.10.sup.17 and 5.times.10.sup.18 molecules/cm.sup.3 and a third quartz glass optical member group whose hydrogen molecule concentration is in the range between 5.times.10.sup.18 to 5.times.10.sup.19 molecules/cm.sup.3. 
Heraeus Quarzglas GmbH Shin-Etsu Quartz Products Co., Ltd.
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Toshiki Akira Hiroyuki
Mori Fujinoki Nishimura