Patent EP0401845B1 successfully refreshed from Google Patents.
EP0401845B1
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Optical members and blanks of synthetic silica glass and method for their production
Assignee: Hereaus Quarzglas & Co KG GmbH
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Filing: 1990-06-08
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Granted: 1994-12-28
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Expires: 2010-06-08
Abstract
Abstract The invention relates to lenses, prisms or other optical members which are subjected to high-power ultraviolet light having a wavelength of about 360 nm or less, or ionizing radiation, particularly optical members for use in laser exposure apparatus for lithography, and to blanks for such optical members. The homogeneity of the refractive index distribution and the resistance to optical deterioration when the optical members are exposed for a long period of time to short wavelength ultraviolet light from a laser beam are improved. The optical members are made of high-purity synthetic silica glass material containing at least about 50 wt. ppm of OH groups, and are doped with hydrogen. The refractive index distribution caused by the fictive temperature distribution during heat treatment in the process of producing high-purity silica glass blanks for optical members in accordance with the present invention is offset by the combined refractive index distribution determined by the OH group concentration distribution or by the OH group concentration distribution and the Cl concentration distribution in the glass.
Inventors
- 👤 Shigeru Yamagata
- 👤 Kyoichi Inaki
- 👤 Toshikatu Matsuya
- 👤 Ralf Takke
- 👤 Stephan Thomas
- 👤 Heinz Fabian
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 11:37
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70216; G03F7/70241; C; C03; C03B; C03B19/00; C03B19/14; C03B19/1415; C03B19/1423; C03B19/1453; C03B32/00; C03C; C03C23/00; C03C23/007; C03C3/00; C03C3/04; C03C3/06; G02; G02B; G02B1/00; C03B2201/00; C03B2201/06; C03B2201/07; C03B2201/20; C03B2201/21; C03B2201/23; C03B2207/00; C03B2207/04; C03B2207/06; C03B2207/08; C03B2207/12; C03B2207/14; C03B2207/20; C03B2207/30; C03B2207/32; C03B2207/36; C03B2207/42; C03C2201/00; C03C2201/06; C03C2201/20; C03C2201/21; C03C2201/23; C03C2203/00; C03C2203/40; C03C2203/50; C03C2203/52; C03C2203/54; Y; Y02; Y02P; Y02P40/00; Y02P40/50; Y02P40/57; Y10; Y10S; Y10S65/00; Y10S65/90
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
78 words
A synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said optical member is made of high-purity synthetic silica glass material which is free from striae in at least one direction corresponding to the incident light and which has an OH group concentration of at least about 50 wt. ppm, and a doped hydrogen molecule concentration of at least about 5 x 10 16 molecules/cm 3 .
Claim 2
Dependent Claim
78 words
A synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said optical member is made of high-purity synthetic silica glass material which is free from striae in at least one direction corresponding to the incident light and which has an OH group concentration of at least about 50 wt. ppm, and a doped hydrogen molecule concentration of at least about 5 x 10 16 molecules/cm 3 .
Claim 3
Dependent Claim
38 words
An optical member as claimed in claim 1, for use with a high-power ultraviolet laser beam having a wavelength shorter than 250 nm, wherein said member has an OH group concentration of at least about 100 wt. ppm.
Claim 4
Dependent Claim
76 words
An optical member as claimed in claim 1, for use with a high-power ultraviolet laser beam having a wavelength shorter than 250 nm, wherein said member has an OH group concentration of at least about 100 wt. ppm, and a doped hydrogen molecule concentration such that when the temperature of said optical member is raised to 1,000° C under vacuum, at least about 1 x 10 20 molecules/m 2 of hydrogen are released from said member.
Claim 5
Dependent Claim
59 words
An optical member as claimed in claim 2, for use with a high-power ultraviolet laser beam having a wavelength shorter than 200 nm, wherein said member has an OH group concentration of at least about 100 wt. ppm, and a doped hydrogen molecule concentration within the range from 5 x 10 16 to 5 x 10 19 mole- cules/cm3.
Claim 6
Dependent Claim
20 words
An optical member as claimed in claim 4, wherein the OH group concentration is at least about 200 wt. ppm.
Claim 7
Dependent Claim
78 words
An optical member as claimed in claim 3, for use with a high-power ultraviolet laser beam having a wavelength shorter than 200 nm, wherein said member has an OH group concentration of at least about 100 wt. ppm, and a doped hydrogen molecule concentration such that when the temperature of said member is raised to 1,000° C under vacuum, from 1 x 10 20 to 1 x 10 23 molecules/m 2 of hydrogen are released from said member.
Claim 8
Dependent Claim
20 words
An optical member as claimed in claim 6, wherein the OH group concentration is at least about 200 wt. ppm.
Claim 9
Dependent Claim
20 words
An optical member as claimed in claim 2, wherein said high-power ultraviolet laser beam is a KrF excimer laser beam.
Claim 10
Dependent Claim
20 words
An optical member as claimed in claim 4, wherein said high-power ultraviolet laser beam is an ArF excimer laser beam.
Claim 11
Dependent Claim
36 words
An optical member as claimed in claim 1, wherein said optical member has a refractive index inhomogeneity (8n) of less than or equal to 2 x 10- s in a plane orthogonal to the incident light.
Claim 12
Dependent Claim
21 words
An optical member as claimed in claim 1, wherein said optical member has a glass structure substantially free from oxygen defects.
Claim 13
Dependent Claim
59 words
An optical member as claimed in claim 1, wherein said optical member has an impurity content such that the total content of Li, Na, and K is 150 ppb or less, the total content of Mg and Ca is 100 ppb or less, and the total content of Ti, Cr, Fe, Ni, and Cu is 50 ppb or less.
Claim 14
Dependent Claim
58 words
An optical member as claimed in claim 1, wherein said optical member has the following impurity contents: Na ≦ 50 ppb, K ≦ 50 ppb, Li ≦ 50 ppb, Mg ≦ 10 ppb, Ca ≦ 10 ppb, Ti ≦ 10 ppb, Cr ≦ 10 ppb, Fe ≦ 10 ppb, Ni Z 10 ppb, and Cu Z 10 ppb.
Claim 15
Dependent Claim
57 words
An optical member as claimed in claim 1, wherein said optical member is selected from the group consisting of lenses, prisms, filters, windows, reflectors, etalon plates, and semifinished products used in a lithography apparatus that uses an excimer laser beam, YAG higher harmonics laser beam, or other high-power ultraviolet laser beam for producing large scale integrated circuits.
Claim 16
Dependent Claim
19 words
An optical member as claimed in claim 1, wherein said optical member is free of striae in three dimensions.
Claim 17
Dependent Claim
20 words
An optical member as claimed in claim 1, wherein said optical member has a birefringence of 5 nm/cm or less.
Claim 18
Dependent Claim
116 words
A blank for a synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said blank is made of a heat treated high-purity silica glass material which is free from striae in at least a direction parallel to the incident light and which contains OH groups, said blank having an OH group concentration distribution in a plane orthogonal to the incident light such that the OH group concentration progressively increases from a minimum concentration region to a maximum concentration region without an inflection point so that said blank has an overall refractive index distribution inhomogeneity (8n) in said plane of 2 x 10 -6 or less.
Claim 19
Dependent Claim
116 words
A blank for a synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said blank is made of a heat treated high-purity silica glass material which is free from striae in at least a direction parallel to the incident light and which contains OH groups, said blank having an OH group concentration distribution in a plane orthogonal to the incident light such that the OH group concentration progressively increases from a minimum concentration region to a maximum concentration region without an inflection point so that said blank has an overall refractive index distribution inhomogeneity (8n) in said plane of 2 x 10 -6 or less.
Claim 20
Dependent Claim
39 words
A blank as claimed in claim 17, wherein said blank has an OH group concentration of at least about 100 wt. ppm, and a doped hydrogen molecule concentration of at least about 5 x 10 16 molecules/cm 3 .
Claim 21
Dependent Claim
59 words
A blank as claimed in claim 17, wherein said blank has an OH group concentration of at least about 100 wt. ppm, and a doped hydrogen molecule concentration such that when the temperature of said blank is raised to 1,000° C under vacuum, at least about 1 x 10 20 molecules/m 2 of hydrogen are released from said blank.
Claim 22
Dependent Claim
121 words
A blank for a synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said blank is made of a high-purity synthetic silica glass material which is free from striae in at least a direction parallel to the incident light, and which contains concentrations of OH groups and chlorine (CI) distributed therein, said blank having a first refractive index distribution due to a combination of the chlorine concentration distribution and the OH group concentration distribution in a plane orthogonal to the incident light, and said first refractive index distribution is substantially offset by a second refractive index distribution due to a fictive temperature distribution caused during heating/cooling treatment of the blank.
Claim 23
Dependent Claim
121 words
A blank for a synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said blank is made of a high-purity synthetic silica glass material which is free from striae in at least a direction parallel to the incident light, and which contains concentrations of OH groups and chlorine (CI) distributed therein, said blank having a first refractive index distribution due to a combination of the chlorine concentration distribution and the OH group concentration distribution in a plane orthogonal to the incident light, and said first refractive index distribution is substantially offset by a second refractive index distribution due to a fictive temperature distribution caused during heating/cooling treatment of the blank.
Claim 24
Dependent Claim
39 words
A blank as claimed in claim 20, wherein said blank has an OH group concentration of at least about 100 wt. ppm and a doped hydrogen molecule concentration of at least about 5 x 10 16 molecules/cm 3 .
Claim 25
Dependent Claim
59 words
A blank as claimed in claim 20, wherein said blank has an OH group concentration of at least about 100 wt. ppm, and a doped hydrogen molecule concentration such that when the temperature of said blank is raised to 1,000° C under vacuum, at least about 1 x 10 20 molecules/m 2 of hydrogen are released from said blank.
Claim 26
Dependent Claim
55 words
A blank as claimed in claim 20, wherein the combination of the concentration distributions is such that the OH group concentration distribution is a concave curve having a minimum value at the center of the blank and the chlorine concentration distribution is a convex curve having a maximum value at the center of the blank.
Claim 27
Dependent Claim
49 words
A blank as claimed in claim 20, wherein the combination of the concentration distributions is such that both the concentration distributions are concave curves, and the relationship between the concentration inhomogeneities (80H and 8CI) is such that the OH group concentration distribution is greater than the chlorine concentration distribution.
Claim 28
Dependent Claim
48 words
A blank as claimed in claim 20, wherein the combination of the concentration distributions is such that both the concentration distributions are convex curves, and the relationship between concentration inhomogeneities (80H and 8CI) is such that the chlorine concentration distribution is greater than the OH group concentration distribution.
Claim 29
Independent Claim
102 words
A method of producing an optical member or blank therefor for use with ultraviolet incident light having a wavelength range shorter than about 360 nm, said method comprising the steps of: forming a blank from high-purity synthetic silica glass containing OH groups in an amount of at least 50 wt. ppm; removing striae from said blank in at least one direction; removing internal strains from said blank by heating the blank at a temperature of at least 1,000° C, and doping said silica glass with hydrogen to a hydrogen molecule concentration of at least about 5 x 10 16 molecules/cm 3 .
Claim 30
Independent Claim
102 words
A method of producing an optical member or blank therefor for use with ultraviolet incident light having a wavelength range shorter than about 360 nm, said method comprising the steps of: forming a blank from high-purity synthetic silica glass containing OH groups in an amount of at least 50 wt. ppm; removing striae from said blank in at least one direction; removing internal strains from said blank by heating the blank at a temperature of at least 1,000° C, and doping said silica glass with hydrogen to a hydrogen molecule concentration of at least about 5 x 10 16 molecules/cm 3 .
Claim 31
Dependent Claim
39 words
A method as claimed in claim 26, further comprising after the striae removing step, the additional step of degassing by heating said synthetic silica glass at 200 to 1,000° C under vacuum to remove gases contained in the glass.
Claim 32
Dependent Claim
42 words
A method as claimed in claim 26, wherein the removing of internal strains and the doping treatment under a heated atmosphere containing hydrogen are carried out simultaneously at a temperature of 1,000 to 1,200° C and at atmospheric pressure or superatmospheric pressure.
Claim 33
Dependent Claim
69 words
A method as claimed in claim 26, wherein after the removal of striae in the synthetic silica glass, the internal strains are removed under a heated atmosphere at a temperature of 1,000 to 1,200° C, and then the doping treatment is subsequently carried out under an elevated pressure atmosphere containing hydrogen heated to a temperature lower than the temperature of the heated atmosphere of the internal strain removing step.
Claim 34
Dependent Claim
43 words
A method as claimed in claim 29, further comprising between the internal strain removing step and the doping step, the additional step of degassing the glass by heating at 200 to 1,000° C under subatmospheric pressure to remove gases contained in the glass.
Claim 35
Dependent Claim
25 words
An optical device comprising in combination an optical member as claimed in claim 1, and a source of radiation arranged to irradiate said optical member.
Claim 36
Dependent Claim
31 words
An optical device as claimed in claim 31, wherein said source of radiation is an ultraviolet laser having a wavelength in the range from about 360 nm to about 150 nm.
Claim 37
Dependent Claim
156 words
A synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said optical member is made of an annealed high-purity synthetic silica glass material which is free from striae in at least one direction corresponding to the incident light and which contains OH groups in an amount of at least about 50 wt. ppm and chlorine (CI) distributed therein, and said optical member is doped with hydrogen sufficient to inhibit decreases in light transmittance over time due to exposure to said ultraviolet light, and said optical member has a first refractive index distribution due to a combination of variations in the chlorine distribution and variations in the OH group distribution in a plane orthogonal to the incident light, and said first refractive index distribution is substantially offset by a second refractive index distribution due to a fictive temperature distribution caused during annealing of said silica glass.
Claim 38
Dependent Claim
156 words
A synthetic silica glass optical member for use with ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said optical member is made of an annealed high-purity synthetic silica glass material which is free from striae in at least one direction corresponding to the incident light and which contains OH groups in an amount of at least about 50 wt. ppm and chlorine (CI) distributed therein, and said optical member is doped with hydrogen sufficient to inhibit decreases in light transmittance over time due to exposure to said ultraviolet light, and said optical member has a first refractive index distribution due to a combination of variations in the chlorine distribution and variations in the OH group distribution in a plane orthogonal to the incident light, and said first refractive index distribution is substantially offset by a second refractive index distribution due to a fictive temperature distribution caused during annealing of said silica glass.
Claim 39
Dependent Claim
146 words
A synthetic silica glass optical member for use with a source of ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said optical member is made of a high-purity synthetic silica glass material which is free from striae in at least one direction corresponding to the incident light and which contains OH groups in an amount of at least about 50 wt. ppm, and said optical member is doped with hydrogen sufficient to inhibit decreases in light transmittance over time due to exposure to said ultraviolet light, said optical member having an OH group concentration distribution in a plane orthogonal to the incident light such that the OH concentration increases progressively from a minimum concentration region to a maximum concentration region without an inflection point so that the refractive index distribution inhomogeneity (8n) in said plane is 2 x 10- s or less.
Claim 40
Dependent Claim
146 words
A synthetic silica glass optical member for use with a source of ultraviolet incident light having a wavelength shorter than about 360 nm, wherein said optical member is made of a high-purity synthetic silica glass material which is free from striae in at least one direction corresponding to the incident light and which contains OH groups in an amount of at least about 50 wt. ppm, and said optical member is doped with hydrogen sufficient to inhibit decreases in light transmittance over time due to exposure to said ultraviolet light, said optical member having an OH group concentration distribution in a plane orthogonal to the incident light such that the OH concentration increases progressively from a minimum concentration region to a maximum concentration region without an inflection point so that the refractive index distribution inhomogeneity (8n) in said plane is 2 x 10- s or less.
References Cited (Backward Citations)
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