Synthetic quartz glass substrate and making method
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsJunichiro Nishida, Kazuo Shirota, Hisashi Yagi, Masaki Takeuchi
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Abstract
A synthetic quartz glass substrate having a controlled hydrogen molecule concentration is prepared by (a) hot shaping a synthetic quartz glass ingot into a glass block, (b) slicing the glass block into a glass plate, (c) annealing the glass plate at 500-1,250° C. for 15-60 hours, (d) hydrogen doping treatment of the glass plate in a hydrogen gas atmosphere at 300-450° C. for 20-40 hours, and (e) dehydrogenation treatment of the glass plate at 200-400° C. for 5-10 hours.
Claims8
A synthetic quartz glass substrate having a pair of major surfaces and a thickness t therebetween, the substrate having a hydrogen molecule concentration at an arbitrary point on the substrate, which has a lowest value of at least 3×1016 molecules/cm3 and a highest value of up to 1×1018 molecules/cm3 in the range from one of the major surfaces to the thickness middle t/2, a maximum at any point in the range from the one of the major surfaces to t/4, and a point having a higher hydrogen molecule concentration than on the one of the major surfaces existing in the interior below the one of the major surfaces, wherein the thickness t is 6.35 mm to 10 mm.
Dependencies are inferred from the claim text.