Blank of titanium-doped glass with a high silica content for a mirror substrate for use in EUV lithography and method for the production thereof

Patent metadata

Field	Value
Publication number	US-9416040-B2
Application number	US-201414569535-A
Country	US
Kind code	B2
Filing date	Dec 12, 2014
Priority date	Sep 30, 2009
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

On the basis of a known method for producing a blank of titanium-doped glass with a high silica content (glass) for a mirror substrate for use in EUV lithography which has a surface region that has an outer contour, is intended to be provided with a reflective coating and is specified as a highly loaded zone when the mirror substrate is used as intended, in order to provide a blank which can be produced at low cost and nevertheless meets high requirements with respect to homogeneity and freedom from blisters and striae, a procedure which comprises the following method steps is proposed: (a) producing a front body of titanium-doped high-quality glass with dimensions more than large enough to enclose the outer contour, (b) producing a cylindrical supporting body from titanium-doped glass, (c) bonding the front body and the supporting body to form a composite body, and (d) working the composite body to form the mirror substrate blank, wherein the step of producing the front body comprises a homogenizing process involving twisting a starting body obtained in the form of a strand by flame hydrolysis of a silicon-containing compound to form a front body blank, and the supporting body is formed as a monolithic glass block with less homogeneity than the front body.

First claim

The invention claimed is:

1. A blank consisting essentially of titanium-doped, highly siliceous glass configured for use as a mirror substrate for use in extreme ultra violet lithography, said blank having a surface area which has an outer contour and which is predetermined to be metalized and which is a highly stressed zone during the intended use of the mirror substrate, wherein the blank is a melt composite body having a front body portion of titanium-doped glass of high homogeneity with a first volume and with dimensions enclosing the outer contour with an oversize, and a support body portion of titanium-doped quartz glass with a second volume, the support body portion being a monolithic glass block of lower homogeneity than the front body portion.

2. The blank according to claim 1 , wherein the front body portion is of a glass that is without striae in three directions.

3. The blank according to claim 1 , wherein the support body portion is of glass that is without striae in one direction.

4. The blank according to claim 1 , wherein the front body portion is of glass that in conformity with DIN 58927 2/70 meets the demands of Bubble Class 2 or better.

5. The blank according to claim 1 , wherein that the support body portion is of glass that in conformity with DIN 58927 2/70 meets the demands of Bubble Class 2 or worse.

6. The blank according to claim 1 , wherein the front body portion is of glass that has a distribution of the titanium concentration that has a maximum deviation from a mean value thereof that is less than 1%.

7. The blank according to claim 1 , wherein the support body portion is of glass that has a distribution of the titanium concentration that has a maximum deviation from a mean value thereof that is less than 5%.

8. The blank according to claim 1 , wherein the front body portion is partly embedded in the support body portion.

9. The blank according to claim 1 , wherein front body portion and support body portion are of glass with nominally identical compositions.

10. The blank according to claim 1 , wherein the second volume is at least twice as large as the first volume.

11. The blank according to claim 1 , wherein the second volume is at least three times as large as the first volume.

Assignees

• Heraeus Quarzglas

Inventors

• Kuehn Bodo

Classifications

• G02B5/10

  with curved faces · CPC title

• Y10T428/22

  Nonparticulate element embedded or inlaid in substrate and visible · CPC title

• C03B2201/42

  doped with titanium · CPC title

• C03B19/1453

  Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering · CPC title

• C03B32/00

  Thermal after-treatment of glass products not provided for in groups {C03B19/00} , C03B25/00 - C03B31/00 {or C03B37/00}, e.g. crystallisation, eliminating gas inclusions or other impurities; {Hot-pressing vitrified, non-porous, shaped glass products} · CPC title