Optical component, comprising a material with a predetermined homogeneity of thermal expansion
View Patent ↗There is provided an optical component. The optical component includes a material having a coefficient of thermal expansion α, where the coefficient of thermal expansion is dependent on location. The following applies to the location-dependent coefficient of thermal expansion: α= α ±Δα, with Δα being the maximum deviation of the coefficient of thermal expansion from the mean value of the coefficient of thermal expansion α of the material. The following homogeneity condition applies to the material: Δα ≤ ( 0.14 + 0.1 · x + 390 x ) · ɛ _ Q . with the progress of the lacation-dependent progress of the coefficient of thermal expansion being periodical with a wavelength x given in mm, and the thermal output which is absorbed by the optical component being designated by Q given in watts (W), the resulting emissivity being designated by ε , and |Δα|in units of ppb K .
1. An optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass, wherein said material has a coefficient of thermal expansion α, that is dependent on location and is periodic with a period x, in mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and
Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
Δα
≤
(
0.14
+
0.1
·
x
+
390
x
)
·
ɛ
_
Q
.
where: {dot over (Q)} is thermal power absorbed by said optical component, in watts, ε is resulting emissivity, and |Δα| is absolute value of Δα, in units of
ppb
K
.
2. The optical component according to claim 1 , wherein
Δα
≤
(
0.07
+
0.05
·
x
+
195
x
)
·
ɛ
_
Q
.
3. The optical component according to claim 1 , wherein
Δα
≤
(
0.0467
+
0.0333
·
x
+
130
x
)
·
ɛ
_
Q
.
4. The optical component according to claim 1 , wherein
Δα
≤
(
0.0350
+
0.025
·
x
+
97.5
x
)
·
ɛ
_
Q
.
5. The optical component according to claim 1 , wherein
Δα
≤
(
0.028
+
0.02
·
x
+
78
x
)
·
ɛ
_
Q
.
6. The optical component according to claim 1 ,
wherein said material is said Ti-doped quartz glass, and
wherein said coefficient of thermal expansion is influenced in a location-dependent manner by a Ti content in said Ti-doped quartz glass.
7. The optical component according to claim 1 ,
wherein said material is said glass ceramic, and
wherein said glass ceramic comprises a share of an amorphous phase and a share of a crystalline phase,
wherein said crystalline phase is induced by seed crystals and is controlled by a heat treatment, and
wherein said coefficient of thermal expansion is influenced in a location-dependent manner by said seed crystals and said heat treatment.
8. The optical component according to claim 1 ,
wherein said coefficient of thermal expansion is temperature-dependant, and
wherein
α (T)=m·(T−T 0 )
where α (T) is a temperature-dependent mean value of said coefficient of thermal expansion,
m is a rise
T is a temperature, and
T 0 is a temperature at which α (T)=0.
9. The optical component according to claim 8 , wherein
|m|<1·10 −6 ·K −2 .
10. The optical component according to claim 1 , further comprising a coating on said material.
11. The optical component according to claim 10 , wherein said optical component is a reticle mask for EUV lithography.
12. The optical component according to claim 10 , wherein said optical component is a mirror for EUV lithography.
13. The optical component according to claim 10 , wherein said coating comprises a material selected from the group consisting of ruthenium, palladium and rhodium.
14. The optical component according to claim 10 , wherein said coating comprises a layer pair selected from the group consisting of:
a layer of Mo and a layer of Si;
a layer of Mo a layer of Be; and
a layer of MoRu and a layer of Be.
15. An illumination system for illuminating a field in a plane with radiation having a wavelength less than or equal to 193 nm, wherein said illumination system comprises:
an optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material has a coefficient of thermal expansion α that is dependent on location
and is periodic with a period x, in mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and
Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
Δα
≤
(
0.14
+
0.1
·
x
+
390
x
)
·
ɛ
_
Q
.
where: {dot over (Q)} is thermal power absorbed by said optical component, in watts, ε is resulting emissivity, and
|Δα| is absolute value of Δα, in units of
ppb
K
.
16. A projection objective for projecting an object in an object plane to an image in an image plane with radiation having a wavelength less than or equal to 193 nm, wherein said projection objective comprises:
an optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material has a coefficient of thermal expansion α that is dependent on location
and is periodic with a period x, in mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and
Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
Δα
≤
(
0.14
+
0.1
·
x
+
390
x
)
·
ɛ
_
Q
.
where: {dot over (Q)} is thermal power absorbed by said optical component, in watts, ε is resulting emissivity, and
|Δα| is absolute value of Δα, in units of
ppb
K
.
17. The projection objective according to claim 16 , wherein said optical component is a mirror.
18. A projection exposure system for microlithography, comprising:
a radiation source that generates radiation;
an illumination system that partly collects said radiation and forwards said radiation with a ring field for illuminating a plane;
a structure-bearing mask on a carrier system, wherein said structure-bearing mask is situated in a plane of said ring field;
a projection objective that projects an illuminated part of said structure-bearing mask to an image field; and
a light-sensitive substrate on a carrier system, wherein said light-sensitive substrate is situated in a plane of said image field,
wherein at least one of the said illumination system, said structure-bearing mask or said projection objective includes an optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material has a coefficient of thermal expansion α that is dependent on location
and is periodic with a period x, in mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and
Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
Δα
≤
(
0.14
+
0.1
·
x
+
390
x
)
·
ɛ
_
Q
.
where: {dot over (Q)} is thermal power absorbed by said optical component, in watts, ε is resulting emissivity, and
|Δα| is absolute value of Δα, in units of
ppb
K
.
19. A method comprising:
(A) illuminating a light-sensitive substrate with a projection exposure system having:
a radiation source that generates radiation;
an illumination system that partly collects said radiation and forwards said radiation with a ring field for illuminating a plane;
a structure-bearing mask on a carrier system, wherein said structure-bearing mask is situated in a plane of said ring field;
a projection objective that projects an illuminated part of said structure-bearing mask to an image field; and
a light-sensitive substrate on a carrier system, wherein said light-sensitive substrate is situated in a plane of said image field,
wherein at least one of said illumination system, said structure-bearing mask or said projection objective includes an optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material has a coefficient of thermal expansion α that is dependent on location and is periodic with a period x, in mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
Δα
≤
(
0.14
+
0.1
·
x
+
390
x
)
·
ɛ
_
Q
.
where: {dot over (Q)} is thermal power absorbed by said optical component, in watts, ε is resulting emissivity, and |Δα| is absolute value of Δα, in units of
ppb
K
.
and
(B) producing a microelectronic component from said light-sensitive substrate.
20. An optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material a coefficient of thermal expansion α that is dependent on location and is periodic with a period greater than or equal to 40 mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
|Δα|≦5
where |Δα| is absolute value of Δα, in units of
ppb
K
.
21. The optical component according to claim 20 ,
wherein said material is said Ti-doped quartz glass, and
wherein said coefficient of thermal expansion is influenced in a location-dependent manner by a Ti content in said Ti-doped quartz glass.
22. The optical component according to claim 20 ,
wherein said material is said glass ceramic, and
wherein said glass ceramic material comprises a share of an amorphous phase and a share of a crystalline phase,
wherein said crystalline phase is induced by seed crystals and is controlled by a heat treatment, and
wherein said coefficient of thermal expansion is influenced in a location-dependent manner by said seed crystals and said heat treatment.
23. The optical component according to claim 20 ,
wherein said coefficient of thermal expansion is temperature-dependent, and
wherein
α (T)=m·(T−T 0 )
where α (T) is a temperature-dependent mean value of said coefficient of thermal expansion,
m is a rise
T is a temperature, and
T 0 is a temperature at which α (T)=0.
24. The optical component according to claim 23 , wherein
|m|<1·10 −6 ·K −2 .
25. The optical component according to claim 20 , further comprising a coating on said material.
26. The optical component according to claim 25 , wherein said optical component is a reticle mask for EUV lithography.
27. The optical component according to claim 25 , wherein said optical component is a mirror for EUV lithography.
28. The optical component according to claim 25 , wherein said coating comprises a material selected from the group consisting of ruthenium, palladium and rhodium.
29. The optical component according to claim 25 , wherein said coating comprises a layer pair selected from the group consisting of:
a layer of Mo and a layer of Si;
a layer of Mo and a layer of Be;
a layer of MoRu and a layer of Be.
30. The optical component of claim 20 , wherein said optical component absorbs thermal power of about 1 watt (W) and has a resulting emissivity of about 0.5.
31. An illumination system for illuminating a field in a plane with radiation having a wavelength less than or equal to 193 nm, wherein said illumination system comprises:
an optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material has a coefficient of thermal expansion α that is dependent on location and is periodic with a period greater than or equal to 40 mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and
Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
|Δα|≦5
where |Δα| is absolute value of Δα, in units of
ppb
K
.
32. A projection objective for projecting an object in an object plane to an image in an image plane with radiation having a wavelength less than or equal to 193 nm, wherein said projection objective comprises:
an optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material has a coefficient of thermal expansion α that is dependent on location and is periodic with a period greater than or equal to 40 mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
|Δα|≦5
where |Δα| is absolute value of Δα, in units of
ppb
K
.
33. A The projection objective according to claim 32 , further comprising a plurality of mirrors for directing said radiation.
34. A projection exposure system for microlithography, comprising:
a radiation source for generating radiation;
an illumination system that partly collects said radiation and forwards said radiation with a ring field for illuminating a plane;
a structure-bearing mask on a carrier system, wherein said structure-bearing mask is situated in a plane of said ring field;
a projection objective that projects an illuminated part of said structure-bearing mask to an image field;
a light-sensitive substrate on a carrier system, wherein said light-sensitive substrate is situated in a plane of said image field,
wherein at least one of said illumination system, said structure-bearing mask or said projection objective includes an optical component comprising:
a material selected from the group consisting of glass ceramic and Ti-doped quartz glass,
wherein said material has a coefficient of thermal expansion α that is dependent on location and is periodic with a period greater than or equal to 40 mm,
wherein
α= α ±Δα,
where: α is a mean value of said coefficient of thermal expansion; and Δα is a maximum deviation of said coefficient of thermal expansion from said mean value,
and
wherein
|Δα|≦5
where |Δα| is absolute value of Δα, in units of
ppb
K
.