	US 11,851,364 B2
	Synthetic quartz glass substrate and making method
Junichiro Nishida, Joetsu (JP); Kazuo Shirota, Joetsu (JP); Hisashi Yagi, Joetsu (JP); and Masaki Takeuchi, Joetsu (JP)
Assigned to SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Filed by SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Filed on Jan. 22, 2019, as Appl. No. 16/254,191.
Claims priority of application No. 2018-008527 (JP), filed on Jan. 23, 2018.
Prior Publication US 2019/0225539 A1, Jul. 25, 2019
Int. Cl. C03C 21/00 (2006.01); C03B 23/04 (2006.01); C03B 25/02 (2006.01); C03C 23/00 (2006.01); C03B 19/14 (2006.01); C03B 32/00 (2006.01); C03C 3/06 (2006.01); C03C 4/00 (2006.01)

CPC C03C 21/007 (2013.01) [C03B 19/1469 (2013.01); C03B 23/04 (2013.01); C03B 25/025 (2013.01); C03B 32/00 (2013.01); C03C 3/06 (2013.01); C03C 4/0071 (2013.01); C03C 23/002 (2013.01); C03C 23/007 (2013.01); C03B 2201/21 (2013.01); C03B 2201/23 (2013.01); C03C 2201/21 (2013.01); C03C 2203/52 (2013.01)]

8 Claims

1. 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 3×10¹⁶molecules/cm³and a highest value of up to 1×10¹⁸molecules/cm³in 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.