Abstract

The dielectric function spectra of low dielectric constant (low-k) materials have been determined using high-precision four-zone null spectroscopic ellipsometry, near-normal incidence reflection spectrometry and Fourier transform infrared transmission spectroscopy. The optical functions over a wide spectral range from 0.03t o 5.4 eV (230 nm to 40.5 µm wavelength region) have been evaluated for representative low-k materials used in the semiconductor industry for inter-layer dielectrics: (1) FLARE – organic spin-on polymer, and (2) HOSP – spin-on hybrid organic-siloxane polymer from the Honeywell Electronic Materials Company.

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References

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  1. S.-W. Chung, J.-H. Shin, N.-H. Park and J. W. Park, "Dielectric properties of hydrogen silsesquioxane films degraded by heat and plasma treatment," Jpn. J. Appl. Phys., Part 1 38, 5214-5219 (1999).
    [CrossRef]
  2. S.-W. Chung, S.-T. Kim, J.-H. Shin, J. K. Kim and J. W. Park, "Comparative study of hydrido organo siloxane polymer and hydrogen silsesquioxane," Jpn. J. Appl. Phys. Part 1 39, 5809-5815 (2000).
    [CrossRef]
  3. J. J. Senkevich and S. B. Desu, "Poly(tetraflouro-p-xylylene), a low dielectric constant chemical vapor polymerized polymer," Appl. Phys. Lett. 72, 258-260 (1998).
    [CrossRef]
  4. N. Aoi, "Novel porous films having low dielectric constants synthesized by liquid phase silylation of spin-on glass sol for intermetal dielectrics," Jpn. J. Appl. Phys. Part 1 36, 1355-1359 (1997).
    [CrossRef]
  5. T. Kikkawa, T. Nagahara and H. Matsuo, "Direct patterning of photosensitive low-dielectric-constant films using electron-beam lithography," Appl. Phys. Lett. 78, 2557-2559 (2001).
    [CrossRef]
  6. S. M. Han and E. S. Aydil, "Reasons for lower dielectric constant of fluorinated SiO2 films," J. Appl. Phys. 83, 2172-2178 (1998).
    [CrossRef]
  7. K. Postava, T. Yamaguchi and M. Horie, "Estimation of the dielectric properties of low-k materials using optical spectroscopy," Appl. Phys. Lett. (2001) (to be published).
    [CrossRef]
  8. I. Ohlidal and D. Franta, Ellipsometry of thin film systems, in: Progress in Optics ed. E. Wolf (North-Holand, Amsterdam, 2000), Vol. 41.
    [CrossRef]
  9. K. Postava and T. Yamaguchi, "Optical functions of low- k materials for interlayer dielectrics," J. Appl. Phys. 89, 2189-2193 (2001).
    [CrossRef]
  10. K. Postava, H. Sueki, M. Aoyama, T. Yamaguchi, Ch. Ino, Y. Igasaki and M. Horie, "Spectroscopic ellipsometry of epitaxial ZnO layer on sapphire substrate," J. Appl. Phys. 87, 7820-7824 (2000).
    [CrossRef]
  11. K. Postava, M. Aoyama and T. Yamaguchi, "Optical characterization of TiN/SiO2(1000nm)/Si system by spectroscopic ellipsometry and reflectometry," Appl. Surf. Sci. 175-176, 270-275 (2001).
    [CrossRef]
  12. K. Postava, H. Sueki, M. Aoyama, T. Yamaguchi, K. Murakami and Y. Igasaki, "Doping effects on optical properties of epitaxial ZnO layers determined by spectroscopic ellipsometry," Appl. Surf. Sci. 175-176, 543-548 (2001).
    [CrossRef]
  13. D. E. Aspens and A. A. Studna, "Dielectric functions and optical parameters of Si, Ge, GaP, GaAs, GaSb, InP, InAs, and InSb from 1.5 to 6.0eV," Phys. Rev. B 27, 985-1009 (1983).
    [CrossRef]
  14. D. F. Edwards, Silicon (Si), in: Handbook of Optical Constants of Solids, ed. E. D. Palik (Academic Press, New York 1998).
  15. H. H. Willard, L. L. Merritt, Jr., J. A. Dean and F. A. Settle, Jr., Instrumental Methods of Analysis, 7th ed., Wadsworth Publishing Company, p. 287.
  16. H.-U. Gremlich, Infrared and Raman Spectroscopy, in: Ullmann's Encyclopedia of Industrial Chemistry, Vol. B5, (Verlagsgesellschaft 1994).
  17. G. E. Jellison, Jr. and F. A. Modine, "Parameterization of the optical functions of amorphous materials in the interband region," Appl. Phys. Lett. 69, 371-373 and 2137 (1996).
    [CrossRef]
  18. H. R. Philipp, Silicon Dioxide (SiO2) (Glass), in: Handbook of Optical Constants of Solids, ed. E. D.Palik (Academic Press, New York 1998).
  19. G. Bader, P. V. Ashrit, F. E. Girouard and Vo-Van Truong, "Reflection--transmission photoellipsometry: theory and experiments," Appl. Opt. 34, 1684-1691 (1995).
    [CrossRef] [PubMed]
  20. I. Ohlidal, "Approximate formulas for the reflectance, transmittance, and scattering losses of nonabsorbing multilayer systems with randomly rough boundaries," J. Opt. Soc. Am. A 10, 158-171 (1993).
    [CrossRef]

Other (20)

S.-W. Chung, J.-H. Shin, N.-H. Park and J. W. Park, "Dielectric properties of hydrogen silsesquioxane films degraded by heat and plasma treatment," Jpn. J. Appl. Phys., Part 1 38, 5214-5219 (1999).
[CrossRef]

S.-W. Chung, S.-T. Kim, J.-H. Shin, J. K. Kim and J. W. Park, "Comparative study of hydrido organo siloxane polymer and hydrogen silsesquioxane," Jpn. J. Appl. Phys. Part 1 39, 5809-5815 (2000).
[CrossRef]

J. J. Senkevich and S. B. Desu, "Poly(tetraflouro-p-xylylene), a low dielectric constant chemical vapor polymerized polymer," Appl. Phys. Lett. 72, 258-260 (1998).
[CrossRef]

N. Aoi, "Novel porous films having low dielectric constants synthesized by liquid phase silylation of spin-on glass sol for intermetal dielectrics," Jpn. J. Appl. Phys. Part 1 36, 1355-1359 (1997).
[CrossRef]

T. Kikkawa, T. Nagahara and H. Matsuo, "Direct patterning of photosensitive low-dielectric-constant films using electron-beam lithography," Appl. Phys. Lett. 78, 2557-2559 (2001).
[CrossRef]

S. M. Han and E. S. Aydil, "Reasons for lower dielectric constant of fluorinated SiO2 films," J. Appl. Phys. 83, 2172-2178 (1998).
[CrossRef]

K. Postava, T. Yamaguchi and M. Horie, "Estimation of the dielectric properties of low-k materials using optical spectroscopy," Appl. Phys. Lett. (2001) (to be published).
[CrossRef]

I. Ohlidal and D. Franta, Ellipsometry of thin film systems, in: Progress in Optics ed. E. Wolf (North-Holand, Amsterdam, 2000), Vol. 41.
[CrossRef]

K. Postava and T. Yamaguchi, "Optical functions of low- k materials for interlayer dielectrics," J. Appl. Phys. 89, 2189-2193 (2001).
[CrossRef]

K. Postava, H. Sueki, M. Aoyama, T. Yamaguchi, Ch. Ino, Y. Igasaki and M. Horie, "Spectroscopic ellipsometry of epitaxial ZnO layer on sapphire substrate," J. Appl. Phys. 87, 7820-7824 (2000).
[CrossRef]

K. Postava, M. Aoyama and T. Yamaguchi, "Optical characterization of TiN/SiO2(1000nm)/Si system by spectroscopic ellipsometry and reflectometry," Appl. Surf. Sci. 175-176, 270-275 (2001).
[CrossRef]

K. Postava, H. Sueki, M. Aoyama, T. Yamaguchi, K. Murakami and Y. Igasaki, "Doping effects on optical properties of epitaxial ZnO layers determined by spectroscopic ellipsometry," Appl. Surf. Sci. 175-176, 543-548 (2001).
[CrossRef]

D. E. Aspens and A. A. Studna, "Dielectric functions and optical parameters of Si, Ge, GaP, GaAs, GaSb, InP, InAs, and InSb from 1.5 to 6.0eV," Phys. Rev. B 27, 985-1009 (1983).
[CrossRef]

D. F. Edwards, Silicon (Si), in: Handbook of Optical Constants of Solids, ed. E. D. Palik (Academic Press, New York 1998).

H. H. Willard, L. L. Merritt, Jr., J. A. Dean and F. A. Settle, Jr., Instrumental Methods of Analysis, 7th ed., Wadsworth Publishing Company, p. 287.

H.-U. Gremlich, Infrared and Raman Spectroscopy, in: Ullmann's Encyclopedia of Industrial Chemistry, Vol. B5, (Verlagsgesellschaft 1994).

G. E. Jellison, Jr. and F. A. Modine, "Parameterization of the optical functions of amorphous materials in the interband region," Appl. Phys. Lett. 69, 371-373 and 2137 (1996).
[CrossRef]

H. R. Philipp, Silicon Dioxide (SiO2) (Glass), in: Handbook of Optical Constants of Solids, ed. E. D.Palik (Academic Press, New York 1998).

G. Bader, P. V. Ashrit, F. E. Girouard and Vo-Van Truong, "Reflection--transmission photoellipsometry: theory and experiments," Appl. Opt. 34, 1684-1691 (1995).
[CrossRef] [PubMed]

I. Ohlidal, "Approximate formulas for the reflectance, transmittance, and scattering losses of nonabsorbing multilayer systems with randomly rough boundaries," J. Opt. Soc. Am. A 10, 158-171 (1993).
[CrossRef]

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Figures (9)

Fig. 1.
Fig. 1.

Spectroellipsometric data at the incidence angle of 80° (a) and near-normal incidence reflectivity spectra (b) of FLARE layer. Measured data (circles, squares) are compared with the model (solid line).

Fig. 2.
Fig. 2.

Optical functions of FLARE in visible, near-infrared and near-ultraviolet range. Real part ε 1 and imaginary part ε 2 of the dielectric function are represented by solid and dashed lines.

Fig. 3.
Fig. 3.

Normal incidence relative transmission spectra of FLARE layer. Measured data (circles) are compared with the model (solid line).

Fig. 4.
Fig. 4.

Optical functions of FLARE in infrared spectral range.

Fig. 5.
Fig. 5.

Spectroellipsometric data at the incidence angle of 70° (a) and near-normal incidence reflectivity spectra (b) of HOSP layer. Measured ellipsometric angles ψ (circles) and Δ (squares) are compared with the model (solid line). Measured reflectivity data (circles) are compared with the model based on Tauc-Lorentz (solid line) and Sellmeier parameterization (dashed line), respectively.

Fig. 6.
Fig. 6.

Refractive index spectrum of HOSP (solid line) is compared with SiO2 tabulated values (dashed line).

Fig. 7.
Fig. 7.

Normal incidence relative transmission spectra of HOSP layer. Measured data (circles) are compared with the model (solid line).

Fig. 8.
Fig. 8.

Optical functions of HOSP in infrared spectral range.

Fig. 9.
Fig. 9.

Influence of incoherent reflections in the thick silicon substrate on the absolute (a) and relative (b) transmittance. The model including the incoherent reflections (solid lines) is compared with a simple transmission simulation neglecting this effect (dashed lines).

Tables (3)

Tables Icon

Table 1. Bake plate and cure conditions for FLARE and HOSP

Tables Icon

Table 2. Results of fit for the FLARE layer.

Tables Icon

Table 3. Results of fit for the HOSP layer.

Equations (4)

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

ε ( E ) = ε 1 + AE 1 2 E 1 2 E 2 + n A n E 0 n 2 E 0 n 2 E 2 + i Γ n E 0 n E ,
ε ( 2 ) ( E ) = AE 0 C ( E E g ) 2 ( E 2 E 0 2 ) 2 + C 2 E 2 1 E [ E > E g ]
= 0 [ E E g ]
T j = t j ( 01 ) 2 t j ( 12 ) 2 e 2 𝕴 ( k z ) d 1 r j ( 10 ) 2 r j ( 12 ) 2 e 4 𝕴 ( k z ) d , j = s , p ,

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