Abstract

We describe a modification to our existing scatterometry technique for extracting the relative phase and amplitude of the electric field diffracted from a grating. This modification represents a novel combination of aspects of ellipsometry and scatterometry to provide improved sensitivity to small variations in the linewidth of subwavelength gratings compared with conventional scatterometer measurements. We present preliminary theoretical and experimental results that illustrate the possibility of the ellipsometric scatterometry technique providing a metrology tool for characterizing sub-0.1-μm-linewidth.

© 1998 Optical Society of America

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References

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  1. S. S. H. Naqvi, J. R. McNeil, R. H. Krukar, K. P. Bishop, “Scatterometry and the simulation of diffraction-based metrology,” Microlithogr. World 2(3), 5–16 (1993).
  2. C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
    [CrossRef]
  3. The National Technology Roadmap for Semiconductors (Semiconductor Industry Association, San Jose, Calif., 1994).
  4. B. K. Minhas, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, “Toward sub-0.1-μm CD measurements using scatterometry,” in Integrated Circuit Metrology, Inspection, and Process Control X, S. K. Jones, ed., Proc. SPIE2725, 729–739 (1996).
  5. S. A. Coulombe, B. K. Minhas, C. J. Raymond, S. S. H. Naqvi, J. R. McNeil, “Scatterometry measurement of sub-0.1-μm linewidth gratings,” submitted to J. Vacuum Sci. Technol. B (1998).
  6. R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light. (North-Holland, Amsterdam, 1977).
  7. J. R. Beattie, “Optical constants of metals in the infra-red—experimental methods,” Philos. Mag. 46, 235–245 (1955).
  8. E. Collett, Polarized Light—Fundamentals and Applications (Marcel Dekker, New York, 1993).
  9. M. G. Moharam, T. K. Gaylord, “Three-dimensional vector coupled-wave analysis of planar-grating diffraction,” J. Opt. Soc. Am. 73, 1105–1112 (1983).
    [CrossRef]
  10. C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vacuum Sci. Technol. B 13, 1484–1495 (1995).
    [CrossRef]

1997 (1)

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

1995 (1)

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vacuum Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

1993 (1)

S. S. H. Naqvi, J. R. McNeil, R. H. Krukar, K. P. Bishop, “Scatterometry and the simulation of diffraction-based metrology,” Microlithogr. World 2(3), 5–16 (1993).

1983 (1)

1955 (1)

J. R. Beattie, “Optical constants of metals in the infra-red—experimental methods,” Philos. Mag. 46, 235–245 (1955).

Azzam, R. M. A.

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light. (North-Holland, Amsterdam, 1977).

Bashara, N. M.

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light. (North-Holland, Amsterdam, 1977).

Beattie, J. R.

J. R. Beattie, “Optical constants of metals in the infra-red—experimental methods,” Philos. Mag. 46, 235–245 (1955).

Bishop, K. P.

S. S. H. Naqvi, J. R. McNeil, R. H. Krukar, K. P. Bishop, “Scatterometry and the simulation of diffraction-based metrology,” Microlithogr. World 2(3), 5–16 (1993).

Collett, E.

E. Collett, Polarized Light—Fundamentals and Applications (Marcel Dekker, New York, 1993).

Coulombe, S. A.

S. A. Coulombe, B. K. Minhas, C. J. Raymond, S. S. H. Naqvi, J. R. McNeil, “Scatterometry measurement of sub-0.1-μm linewidth gratings,” submitted to J. Vacuum Sci. Technol. B (1998).

Gaylord, T. K.

Hosch, J. W.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

Krukar, R. H.

S. S. H. Naqvi, J. R. McNeil, R. H. Krukar, K. P. Bishop, “Scatterometry and the simulation of diffraction-based metrology,” Microlithogr. World 2(3), 5–16 (1993).

McNeil, J. R.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vacuum Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

S. S. H. Naqvi, J. R. McNeil, R. H. Krukar, K. P. Bishop, “Scatterometry and the simulation of diffraction-based metrology,” Microlithogr. World 2(3), 5–16 (1993).

B. K. Minhas, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, “Toward sub-0.1-μm CD measurements using scatterometry,” in Integrated Circuit Metrology, Inspection, and Process Control X, S. K. Jones, ed., Proc. SPIE2725, 729–739 (1996).

S. A. Coulombe, B. K. Minhas, C. J. Raymond, S. S. H. Naqvi, J. R. McNeil, “Scatterometry measurement of sub-0.1-μm linewidth gratings,” submitted to J. Vacuum Sci. Technol. B (1998).

Minhas, B. K.

S. A. Coulombe, B. K. Minhas, C. J. Raymond, S. S. H. Naqvi, J. R. McNeil, “Scatterometry measurement of sub-0.1-μm linewidth gratings,” submitted to J. Vacuum Sci. Technol. B (1998).

B. K. Minhas, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, “Toward sub-0.1-μm CD measurements using scatterometry,” in Integrated Circuit Metrology, Inspection, and Process Control X, S. K. Jones, ed., Proc. SPIE2725, 729–739 (1996).

Moharam, M. G.

Murnane, M. R.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vacuum Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

Naqvi, S. S. H.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vacuum Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

S. S. H. Naqvi, J. R. McNeil, R. H. Krukar, K. P. Bishop, “Scatterometry and the simulation of diffraction-based metrology,” Microlithogr. World 2(3), 5–16 (1993).

B. K. Minhas, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, “Toward sub-0.1-μm CD measurements using scatterometry,” in Integrated Circuit Metrology, Inspection, and Process Control X, S. K. Jones, ed., Proc. SPIE2725, 729–739 (1996).

S. A. Coulombe, B. K. Minhas, C. J. Raymond, S. S. H. Naqvi, J. R. McNeil, “Scatterometry measurement of sub-0.1-μm linewidth gratings,” submitted to J. Vacuum Sci. Technol. B (1998).

Prins, S. L.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

B. K. Minhas, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, “Toward sub-0.1-μm CD measurements using scatterometry,” in Integrated Circuit Metrology, Inspection, and Process Control X, S. K. Jones, ed., Proc. SPIE2725, 729–739 (1996).

Raymond, C. J.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vacuum Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

S. A. Coulombe, B. K. Minhas, C. J. Raymond, S. S. H. Naqvi, J. R. McNeil, “Scatterometry measurement of sub-0.1-μm linewidth gratings,” submitted to J. Vacuum Sci. Technol. B (1998).

J. Opt. Soc. Am. (1)

J. Vacuum Sci. Technol. B (2)

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vacuum Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. W. Hosch, J. R. McNeil, “Multiparameter grating metrology using optical scatterometry,” J. Vacuum Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

Microlithogr. World (1)

S. S. H. Naqvi, J. R. McNeil, R. H. Krukar, K. P. Bishop, “Scatterometry and the simulation of diffraction-based metrology,” Microlithogr. World 2(3), 5–16 (1993).

Philos. Mag. (1)

J. R. Beattie, “Optical constants of metals in the infra-red—experimental methods,” Philos. Mag. 46, 235–245 (1955).

Other (5)

E. Collett, Polarized Light—Fundamentals and Applications (Marcel Dekker, New York, 1993).

The National Technology Roadmap for Semiconductors (Semiconductor Industry Association, San Jose, Calif., 1994).

B. K. Minhas, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, “Toward sub-0.1-μm CD measurements using scatterometry,” in Integrated Circuit Metrology, Inspection, and Process Control X, S. K. Jones, ed., Proc. SPIE2725, 729–739 (1996).

S. A. Coulombe, B. K. Minhas, C. J. Raymond, S. S. H. Naqvi, J. R. McNeil, “Scatterometry measurement of sub-0.1-μm linewidth gratings,” submitted to J. Vacuum Sci. Technol. B (1998).

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light. (North-Holland, Amsterdam, 1977).

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Figures (5)

Fig. 1
Fig. 1

Lack of diffraction sensitivity to linewidth variations for conventional scatterometer simulations for a 0.2-μm-pitch InP grating with a binary profile: grating height, 0.1 μm; illuminating beam, TE-polarized He–Ne laser (λ = 633 nm).

Fig. 2
Fig. 2

Ellipsometric scatterometer arrangement.

Fig. 3
Fig. 3

Comparison of experiment versus theory for a 1.0-μm developed photoresist grating (n = 1.576, k = 0.001) on a Si substrate. The grating has a binary profile with a linewidth of 0.53 μm and height of 1.0 μm. The incident beam is linearly polarized with P = 45° and is from a He–Ne laser (λ = 633 nm). The grating is mounted in classical configuration, i.e., ϕ = 0°: (a) Ψ versus incidence angle θ; (b) |Δ| versus incidence angle θ.

Fig. 4
Fig. 4

Numerical modeling results from using rigorous coupled-wave analysis showing diffraction sensitivity to 2-nm-linewidth variations for a 0.2-μm-pitch InP grating. The grating is assumed to have a binary profile with a height of 0.1 μm. The illuminating beam is linearly polarized with P = 45° and λ = 633 nm. The grating is mounted in a classical configuration, i.e., ϕ = 0°: (a) Ψ versus incidence angle θ; (b) Δ versus incidence angle θ.

Fig. 5
Fig. 5

Numerical modeling results from using rigorous coupled-wave analysis showing diffraction sensitivity to 2-nm-linewidth variations for a 0.2-μm-pitch developed photoresist grating (n = 1.576) on a Si substrate. The grating is assumed to have a binary profile with a height of 0.7 μm. The illuminating beam is linearly polarized with P = 45° and λ = 633 nm. The grating is mounted in a conical configuration with ϕ = 90°: (a) Ψ versus incidence angle θ; (b) Δ versus incidence angle θ.

Equations (7)

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ρ = E rp / E ip / E rs / E is = tan   Ψ   exp i Δ .
E x E y = cos 2   A cos   A   sin   A cos   A   sin   A sin 2   A R pp R ps R sp R ss cos 2   P cos   P   sin   P cos   P   sin   P sin 2   P 0 1 A × R × P .
I A ,   P ,   θ = cos   P   sin   P | R pp | cos   A 2 + sin 2   P | R ss | sin   A 2 + cos   P   sin 3   P | R pp R ss | cos Δ sin   2 A .
I 0 ° ,   45 ° ,   θ = | R pp | 2 / 4 ,
I 45 ° ,   45 ° ,   θ = 1 / 4 | R pp | 2 + | R ss | 2 / 2 + | R pp R ss | cos Δ ,
I 90 ° ,   45 ° ,   θ = | R ss | 2 / 4 ,
I 135 ° ,   45 ° ,   θ = 1 / 4 | R pp | 2 + | R ss | 2 / 2 - | R pp R ss | cos Δ .

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