Abstract

Optically high quality coatings of fluoride materials are required in deep ultraviolet (DUV) lithography. We have applied ion-beam sputtering (IBS) to obtain fluoride films with smooth surfaces. The extinction coefficients were of the order of 10-4 at the wavelength of 193nm due to the reduction of their absorption loss. The transmittance of the MgF2/GdF3 antireflection coating was as high as 99.7% at the wavelength of 193nm. The surfaces of the IBS deposited films were so smooth that the surface roughness of the AlF3/GdF3 film was comparable with that of the CaF2 substrate. The MgF2/GdF3 coating fulfilled the temperature and humidity requirements of military specification. Thus, the IBS deposited fluoride films are promising candidate for use in the DUV lithography optics.

© 2006 Optical Society of America

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References

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  1. T. Yoshida, K. Nishimoto, K. Etoh, and I. Kataoka, 'Development of high-reflection mirrors of fluoride multilayers for F2 excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 41, 5751-5752 (2002).
    [CrossRef]
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    [CrossRef]
  3. S. Owa and H. Nagasaki, 'Immersion lithography; its potential performance and issues,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 724-733 (2003).
    [CrossRef]
  4. D. Ristau, S. Günster, S. Bosch, A. Duparré, E. Masetti, J. Ferré-Borrull, G. Kiriakidis, F. Peiró, E. Quesnel, and A. Tikhonravov, 'Ultraviolet optical and microstructural properties of MgF2 and LaF3 coatings deposited by ion-beam sputtering and boat and electron-beam evaporation,' Appl. Opt. 41, 3196-3204 (2002).
    [CrossRef] [PubMed]
  5. Y. Taki, 'Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography,' Vacuum 74, 431-435 (2004).
    [CrossRef]
  6. J. C. Manifacier, J. Gasiot, and J. P. Fillard, 'A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin film,' J. Phys. E 9, 1002-1004 (1976).
    [CrossRef]
  7. H. E. Bennett and J. O. Porteus, 'Relation between surface roughness and specular reflectance at normal incidence,' J. Opt. Soc. Am. 51, 123-129 (1961).
    [CrossRef]
  8. 'Military Specification MILC-48497A' (U.S. Army Armament Research and Development Command, Dover, New Jersey, 1980).
  9. R. W. G. Wyckoff, Crystal Structures, 2nd ed. (Interscience Publishers, New York, 1963), Vol. 2.
  10. T. Hahn, International Tables for Crystallography Space-Group Symmetry, 4th ed. (Kluwer Academic, Dordrecht, 1995).
  11. T. Yoshida, K. Nishimoto, and K. Etoh, 'Fluoride antireflection multilayers with high transmittance for ArF excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 43, 258-260 (2004).
    [CrossRef]

2004 (2)

Y. Taki, 'Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography,' Vacuum 74, 431-435 (2004).
[CrossRef]

T. Yoshida, K. Nishimoto, and K. Etoh, 'Fluoride antireflection multilayers with high transmittance for ArF excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 43, 258-260 (2004).
[CrossRef]

2003 (2)

B. W. Smith, H. Kang, A. Bourov, F. Cropanese, and Y. Fan, 'Water immersion optical lithography for the 45-nm node,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 679-682 (2003).
[CrossRef]

S. Owa and H. Nagasaki, 'Immersion lithography; its potential performance and issues,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 724-733 (2003).
[CrossRef]

2002 (2)

1976 (1)

J. C. Manifacier, J. Gasiot, and J. P. Fillard, 'A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin film,' J. Phys. E 9, 1002-1004 (1976).
[CrossRef]

1961 (1)

Bennett, H. E.

Bosch, S.

Bourov, A.

B. W. Smith, H. Kang, A. Bourov, F. Cropanese, and Y. Fan, 'Water immersion optical lithography for the 45-nm node,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 679-682 (2003).
[CrossRef]

Cropanese, F.

B. W. Smith, H. Kang, A. Bourov, F. Cropanese, and Y. Fan, 'Water immersion optical lithography for the 45-nm node,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 679-682 (2003).
[CrossRef]

Duparré, A.

Etoh, K.

T. Yoshida, K. Nishimoto, and K. Etoh, 'Fluoride antireflection multilayers with high transmittance for ArF excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 43, 258-260 (2004).
[CrossRef]

T. Yoshida, K. Nishimoto, K. Etoh, and I. Kataoka, 'Development of high-reflection mirrors of fluoride multilayers for F2 excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 41, 5751-5752 (2002).
[CrossRef]

Fan, Y.

B. W. Smith, H. Kang, A. Bourov, F. Cropanese, and Y. Fan, 'Water immersion optical lithography for the 45-nm node,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 679-682 (2003).
[CrossRef]

Ferré-Borrull, J.

Fillard, J. P.

J. C. Manifacier, J. Gasiot, and J. P. Fillard, 'A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin film,' J. Phys. E 9, 1002-1004 (1976).
[CrossRef]

Gasiot, J.

J. C. Manifacier, J. Gasiot, and J. P. Fillard, 'A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin film,' J. Phys. E 9, 1002-1004 (1976).
[CrossRef]

Günster, S.

Hahn, T.

T. Hahn, International Tables for Crystallography Space-Group Symmetry, 4th ed. (Kluwer Academic, Dordrecht, 1995).

Kang, H.

B. W. Smith, H. Kang, A. Bourov, F. Cropanese, and Y. Fan, 'Water immersion optical lithography for the 45-nm node,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 679-682 (2003).
[CrossRef]

Kataoka, I.

T. Yoshida, K. Nishimoto, K. Etoh, and I. Kataoka, 'Development of high-reflection mirrors of fluoride multilayers for F2 excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 41, 5751-5752 (2002).
[CrossRef]

Kiriakidis, G.

Manifacier, J. C.

J. C. Manifacier, J. Gasiot, and J. P. Fillard, 'A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin film,' J. Phys. E 9, 1002-1004 (1976).
[CrossRef]

Masetti, E.

Nagasaki, H.

S. Owa and H. Nagasaki, 'Immersion lithography; its potential performance and issues,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 724-733 (2003).
[CrossRef]

Nishimoto, K.

T. Yoshida, K. Nishimoto, and K. Etoh, 'Fluoride antireflection multilayers with high transmittance for ArF excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 43, 258-260 (2004).
[CrossRef]

T. Yoshida, K. Nishimoto, K. Etoh, and I. Kataoka, 'Development of high-reflection mirrors of fluoride multilayers for F2 excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 41, 5751-5752 (2002).
[CrossRef]

Owa, S.

S. Owa and H. Nagasaki, 'Immersion lithography; its potential performance and issues,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 724-733 (2003).
[CrossRef]

Peiró, F.

Porteus, J. O.

Quesnel, E.

Ristau, D.

Smith, B. W.

B. W. Smith, H. Kang, A. Bourov, F. Cropanese, and Y. Fan, 'Water immersion optical lithography for the 45-nm node,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 679-682 (2003).
[CrossRef]

Taki, Y.

Y. Taki, 'Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography,' Vacuum 74, 431-435 (2004).
[CrossRef]

Tikhonravov, A.

Wyckoff, R. W. G.

R. W. G. Wyckoff, Crystal Structures, 2nd ed. (Interscience Publishers, New York, 1963), Vol. 2.

Yoshida, T.

T. Yoshida, K. Nishimoto, and K. Etoh, 'Fluoride antireflection multilayers with high transmittance for ArF excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 43, 258-260 (2004).
[CrossRef]

T. Yoshida, K. Nishimoto, K. Etoh, and I. Kataoka, 'Development of high-reflection mirrors of fluoride multilayers for F2 excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 41, 5751-5752 (2002).
[CrossRef]

Appl. Opt. (1)

J. Opt. Soc. Am. (1)

J. Phys. E (1)

J. C. Manifacier, J. Gasiot, and J. P. Fillard, 'A simple method for the determination of the optical constants n, k and the thickness of a weakly absorbing thin film,' J. Phys. E 9, 1002-1004 (1976).
[CrossRef]

Jpn. J. Appl. Phys. (2)

T. Yoshida, K. Nishimoto, and K. Etoh, 'Fluoride antireflection multilayers with high transmittance for ArF excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 43, 258-260 (2004).
[CrossRef]

T. Yoshida, K. Nishimoto, K. Etoh, and I. Kataoka, 'Development of high-reflection mirrors of fluoride multilayers for F2 excimer laser by ion beam sputtering method,' Jpn. J. Appl. Phys. 41, 5751-5752 (2002).
[CrossRef]

Proc. SPIE (2)

B. W. Smith, H. Kang, A. Bourov, F. Cropanese, and Y. Fan, 'Water immersion optical lithography for the 45-nm node,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 679-682 (2003).
[CrossRef]

S. Owa and H. Nagasaki, 'Immersion lithography; its potential performance and issues,' in Optical Microlithography XVI, A. Yen, ed., Proc. SPIE 5040, 724-733 (2003).
[CrossRef]

Vacuum (1)

Y. Taki, 'Film structure and optical constants of magnetron-sputtered fluoride films for deep ultraviolet lithography,' Vacuum 74, 431-435 (2004).
[CrossRef]

Other (3)

'Military Specification MILC-48497A' (U.S. Army Armament Research and Development Command, Dover, New Jersey, 1980).

R. W. G. Wyckoff, Crystal Structures, 2nd ed. (Interscience Publishers, New York, 1963), Vol. 2.

T. Hahn, International Tables for Crystallography Space-Group Symmetry, 4th ed. (Kluwer Academic, Dordrecht, 1995).

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Figures (7)

Fig. 1
Fig. 1

Schematic of the IBS system.

Fig. 2
Fig. 2

(Color online) Transmittance spectra of each fluoride single layer and CaF 2 substrate.

Fig. 3
Fig. 3

XRD spectra of the fluoride films on CaF 2 ( 111 ) substrates: (a) AlF 3 film, (b) MgF 2 film, (c) GdF 3 film.

Fig. 4
Fig. 4

(Color online) Measured (solid curve) and calculated (open circles) transmittance and reflectance spectra of the antireflection coatings: (a) MgF 2 / GdF 3 and (b) AlF 3 / GdF 3 .

Fig. 5
Fig. 5

(Color online) AFM surface images of the antireflection coatings and CaF 2 substrate. The left is the X–Y plane image, and the right is the three-dimensional image. (a) MgF 2 / GdF 3 coating fabricated by the IBS method. (b) MgF 2 / GdF 3 coating fabricated by the evaporation method. (c) AlF 3 / GdF 3 coating fabricated by the IBS method. (d) CaF 2 substrate.

Fig. 6
Fig. 6

Cross-sectional scanning electron microscope image of the antireflection coating.

Fig. 7
Fig. 7

(Color online) Transmittance and reflectance spectra after temperature and humidity tests. The solid and the dotted curves indicate the spectra before and after tests, respectively.

Tables (5)

Tables Icon

Table 1 Temperature Test Parameters

Tables Icon

Table 2 Humidity Test Parameters

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Table 3 Optical Constants of Fluoride Single Layer at the Wavelength of 193.4 nm

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Table 4 Contaminant Contents of Fluoride Films by XPS Analysis

Tables Icon

Table 5 Surface Roughness and Scattering Losses at 193 nm of the Antireflection Coatings

Equations (1)

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L sca = 1 exp ( 4 πδ 193 ) 2 .

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