Abstract

Single-layer films of Ta2O5 and multilayer thin-film filters of Ta2O5 and SiO2 were deposited by ion-beam-sputter deposition. Postdeposition annealing of the structures resulted in increased optical thickness of the films, resulting in an upward shift in the wavelength of the transmission-reflection spectra. Modeling of the single-layer films by means of the effective media approximation indicates an increase in the void fraction of the film after annealing. This increase is consistent with an observed decrease in refractive index and an increase in physical film thickness. The multilayer structures, deposited on substrates of varying coefficient of thermal expansion (CTE), were annealed at various temperatures, and the change in the center wavelength was measured. The measured change is dependent on the annealing temperature and the substrate CTE, indicating that the increase in the void fraction is caused in part by thermally induced stress during the annealing process. A simple model is proposed that relates the void fraction present in the films after annealing with the substrate CTE and the annealing temperature.

© 2004 Optical Society of America

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References

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  1. A. MacLeod, Thin Film Optical Filters, 3rd ed. (Institute of Physics, London, 2001).
    [CrossRef]
  2. H. Takashashi, “Temperature stability of thin-film narrow-bandpass filters produced by ion-assisted deposition,” Appl. Opt. 34, 667–675 (1995).
    [CrossRef] [PubMed]
  3. Y. Z. Hu, S. P. Tay, “Characterization of high-K dielectric ZrO2 films annealed by rapid thermal processing,” J. Vac. Sci. Technol. B 19, 1706–1714 (2001).
    [CrossRef]
  4. R. Thielsch, A. Gatto, N. Kaiser, “Mechanical stress and thermal-elastic properties of oxide coatings for use in deep-ultraviolet spectral region,” Appl. Opt. 41, 3211–3217 (2002).
    [CrossRef] [PubMed]
  5. S. M. Lee, A. Dummer, C. Montcalm, “Annealing effects on the properties of optical filters,” in Proceedings of the Society of Vacuum Coaters 45th Annual Technical Conference Proceedings (Society of Vacuum Coaters, Albuquerque, N. Mex., 2002), pp. 220–223.
  6. The Thin Film Center Inc., Essential Macleod software (The Thin Film Center, Inc., 2745 E Via Rotonda, Tucson, Ariz., 85716, 2003).
  7. D. Stroud, “The effective medium approximation: some recent developments,” Superlattices Microstruct. 23, 567–573 (1998).
    [CrossRef]
  8. H. Tompkins, W. McGahan, Spectroscopic Ellipsometry and Reflectometry (Wiley, New York, 1999).
  9. T. U. Ryu, S. H. Hahn, S. W. Kim, E. J. Kim, “Optical, mechanical and thermal properties of MgF2–ZnS and MgF2–Ta2O5 composite thin films deposited by coevaporation,” Opt. Eng. 39, 3207–3213 (2000).
    [CrossRef]
  10. M. Ohring, Materials Science of Thin Films (Academic, New York, 1992).
  11. H. Demiryont, J. Sites, K. Geib, “Effects of oxygen content on the optical properties of tantalum oxide films deposited by ion-beam sputtering,” Appl. Opt. 24, 490–495 (1985).
    [CrossRef] [PubMed]

2002

2001

Y. Z. Hu, S. P. Tay, “Characterization of high-K dielectric ZrO2 films annealed by rapid thermal processing,” J. Vac. Sci. Technol. B 19, 1706–1714 (2001).
[CrossRef]

2000

T. U. Ryu, S. H. Hahn, S. W. Kim, E. J. Kim, “Optical, mechanical and thermal properties of MgF2–ZnS and MgF2–Ta2O5 composite thin films deposited by coevaporation,” Opt. Eng. 39, 3207–3213 (2000).
[CrossRef]

1998

D. Stroud, “The effective medium approximation: some recent developments,” Superlattices Microstruct. 23, 567–573 (1998).
[CrossRef]

1995

1985

Demiryont, H.

Dummer, A.

S. M. Lee, A. Dummer, C. Montcalm, “Annealing effects on the properties of optical filters,” in Proceedings of the Society of Vacuum Coaters 45th Annual Technical Conference Proceedings (Society of Vacuum Coaters, Albuquerque, N. Mex., 2002), pp. 220–223.

Gatto, A.

Geib, K.

Hahn, S. H.

T. U. Ryu, S. H. Hahn, S. W. Kim, E. J. Kim, “Optical, mechanical and thermal properties of MgF2–ZnS and MgF2–Ta2O5 composite thin films deposited by coevaporation,” Opt. Eng. 39, 3207–3213 (2000).
[CrossRef]

Hu, Y. Z.

Y. Z. Hu, S. P. Tay, “Characterization of high-K dielectric ZrO2 films annealed by rapid thermal processing,” J. Vac. Sci. Technol. B 19, 1706–1714 (2001).
[CrossRef]

Kaiser, N.

Kim, E. J.

T. U. Ryu, S. H. Hahn, S. W. Kim, E. J. Kim, “Optical, mechanical and thermal properties of MgF2–ZnS and MgF2–Ta2O5 composite thin films deposited by coevaporation,” Opt. Eng. 39, 3207–3213 (2000).
[CrossRef]

Kim, S. W.

T. U. Ryu, S. H. Hahn, S. W. Kim, E. J. Kim, “Optical, mechanical and thermal properties of MgF2–ZnS and MgF2–Ta2O5 composite thin films deposited by coevaporation,” Opt. Eng. 39, 3207–3213 (2000).
[CrossRef]

Lee, S. M.

S. M. Lee, A. Dummer, C. Montcalm, “Annealing effects on the properties of optical filters,” in Proceedings of the Society of Vacuum Coaters 45th Annual Technical Conference Proceedings (Society of Vacuum Coaters, Albuquerque, N. Mex., 2002), pp. 220–223.

MacLeod, A.

A. MacLeod, Thin Film Optical Filters, 3rd ed. (Institute of Physics, London, 2001).
[CrossRef]

McGahan, W.

H. Tompkins, W. McGahan, Spectroscopic Ellipsometry and Reflectometry (Wiley, New York, 1999).

Montcalm, C.

S. M. Lee, A. Dummer, C. Montcalm, “Annealing effects on the properties of optical filters,” in Proceedings of the Society of Vacuum Coaters 45th Annual Technical Conference Proceedings (Society of Vacuum Coaters, Albuquerque, N. Mex., 2002), pp. 220–223.

Ohring, M.

M. Ohring, Materials Science of Thin Films (Academic, New York, 1992).

Ryu, T. U.

T. U. Ryu, S. H. Hahn, S. W. Kim, E. J. Kim, “Optical, mechanical and thermal properties of MgF2–ZnS and MgF2–Ta2O5 composite thin films deposited by coevaporation,” Opt. Eng. 39, 3207–3213 (2000).
[CrossRef]

Sites, J.

Stroud, D.

D. Stroud, “The effective medium approximation: some recent developments,” Superlattices Microstruct. 23, 567–573 (1998).
[CrossRef]

Takashashi, H.

Tay, S. P.

Y. Z. Hu, S. P. Tay, “Characterization of high-K dielectric ZrO2 films annealed by rapid thermal processing,” J. Vac. Sci. Technol. B 19, 1706–1714 (2001).
[CrossRef]

Thielsch, R.

Tompkins, H.

H. Tompkins, W. McGahan, Spectroscopic Ellipsometry and Reflectometry (Wiley, New York, 1999).

Appl. Opt.

J. Vac. Sci. Technol. B

Y. Z. Hu, S. P. Tay, “Characterization of high-K dielectric ZrO2 films annealed by rapid thermal processing,” J. Vac. Sci. Technol. B 19, 1706–1714 (2001).
[CrossRef]

Opt. Eng.

T. U. Ryu, S. H. Hahn, S. W. Kim, E. J. Kim, “Optical, mechanical and thermal properties of MgF2–ZnS and MgF2–Ta2O5 composite thin films deposited by coevaporation,” Opt. Eng. 39, 3207–3213 (2000).
[CrossRef]

Superlattices Microstruct.

D. Stroud, “The effective medium approximation: some recent developments,” Superlattices Microstruct. 23, 567–573 (1998).
[CrossRef]

Other

H. Tompkins, W. McGahan, Spectroscopic Ellipsometry and Reflectometry (Wiley, New York, 1999).

S. M. Lee, A. Dummer, C. Montcalm, “Annealing effects on the properties of optical filters,” in Proceedings of the Society of Vacuum Coaters 45th Annual Technical Conference Proceedings (Society of Vacuum Coaters, Albuquerque, N. Mex., 2002), pp. 220–223.

The Thin Film Center Inc., Essential Macleod software (The Thin Film Center, Inc., 2745 E Via Rotonda, Tucson, Ariz., 85716, 2003).

M. Ohring, Materials Science of Thin Films (Academic, New York, 1992).

A. MacLeod, Thin Film Optical Filters, 3rd ed. (Institute of Physics, London, 2001).
[CrossRef]

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Figures (5)

Fig. 1
Fig. 1

Single-layer Ta2O5 index plot before and after annealing.

Fig. 2
Fig. 2

Laser line filter after annealing. Line represents the best fit for exponential transition.

Fig. 3
Fig. 3

Filter on substrates FS and BK7, showing differences in the effect of annealing.

Fig. 4
Fig. 4

CWL shift dependence as a function of substrate CTE. Lines are presented only for guides and do not represent a best-fit line or an interpretation of the data. ppm, parts in 106.

Fig. 5
Fig. 5

Correlation of the experimentally measured percent shift in the CWL with that predicted by the model relative percent shift in CWL to the substrate CTE and the annealing temperature.

Tables (4)

Tables Icon

Table 1 Substrate CTEsa

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Table 2 Filter Designs Used in Testing

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Table 3 Calculated Void Fraction for Ta2O5 Films

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Table 4 Results of Fitting to CWL Shift Data Set

Equations (9)

Equations on this page are rendered with MathJax. Learn more.

ΔCWL=λλ0-1,
X0ε0-εε0+2ε+XVεV-εεV+2ε=0, X0+XV=1, ε=εR+iεI=n-ik2,
σF=αS-αFΔTEF1-υF,
ν=V-VV,
d=d0+δ=d0+d0ν,
nν=n0-mν,
CWLshift=nνd-n0d0n0d0=ν-mn0ν-mn0ν2.
R=β1exp-σTHNαF-αSΔT,
υ=β11-σTHNαF-αSΔT+β0,

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