Abstract

We present a spectroscopic, autocollimating ellipsometer capable of operating at arbitrary angles of incidence. Linearly polarized light incident on a sample is circularly polarized on reflection, ensuring that the retroreflected beam is orthogonal to the input polarization state. In order to achieve this at arbitrary angles of incidence, a Soleil–Babinet compensator (SBC) is introduced with its fast axis fixed horizontally. Nulling is achieved by varying the SBC delay and the azimuthal angle of the input linear polarization. A single calibration equation at a fixed wavelength and a knowledge of the wavelength dependence of the compensator birefringence enables the delay to be accurately calculated at any wavelength. Single- wavelength, variable angle of incidence measurements made on a thick gold film are in excellent agreement with those obtained with a traditional null ellipsometer. Spectroscopic measurements at a fixed angle of incidence of a silicon dioxide film on a silicon substrate yield thicknesses that are in excel lent agreement with independent measurements made with a null ellipsometer and a commercial instrument.

© 2010 Optical Society of America

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References

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  1. H. M. O’Bryan, “The optical constants of several metals in vacuum,” J. Opt. Soc. Am. 26, 122–127 (1936).
    [CrossRef]
  2. D. Brewster, “On the phenomena and laws of elliptic polarization, as exhibited in the action of metals upon light,” Phil. Trans. Royal Soc. 120, 287–326 (1830).
    [CrossRef]
  3. M. Yamamoto, “New type of precision ellipsometer without employing a compensator,” Opt. Commun. 10, 200–202 (1974).
    [CrossRef]
  4. M. Yamamoto and O. S. Heavens, “A vacuum automatic ellipsometer for principal angle of incidence measurement,” Surf. Sci. 96, 202–216 (1980).
    [CrossRef]
  5. T. Yamaguchi and H. Takahashi, “Autocollimation-type ellipsometer for monitoring film growth through a single window,” Appl. Opt. 15, 677–680 (1976).
    [CrossRef] [PubMed]
  6. J. F. Archard, P. L. Clegg, and A. M. Taylor, “Photoelectric analysis of elliptically polarized light,” Proc. Phys. Soc. Lond. B 65, 758–768 (1952).
    [CrossRef]
  7. D. Chandler-Horowitz and G. A. Candela, “Principal angle spectroscopic ellipsometry utilizing a rotating analyzer,” Appl. Opt. 21, 2972–2977 (1982).
    [CrossRef] [PubMed]
  8. L. Schrottke and G. Jungk, “Automated null ellipsometer with rotating analyzer,” Rev. Sci. Instrum. 65, 3657–3660 (1994).
    [CrossRef]
  9. D. E. Aspnes, “Optimizing precision of rotating-analyzer ellipsometers,” J. Opt. Soc. Am. 64, 639–646 (1974).
    [CrossRef]
  10. D. E. Aspnes, “Optimizing precision of rotating-analyzer and rotating-compensator ellipsometers,” J. Opt. Soc. Am. A 21, 403–410 (2004).
    [CrossRef]
  11. F. Bréhat, B. Wyncke, and A. M. Benoit, “Method for birefringence measurements as a function of wavelength in the visible range, applied to the reinvestigation of crystal quartz,” J. Phys. D: Appl. Phys. 32, 227–233 (1999).
    [CrossRef]
  12. R. M. A. Azzam and N. M. BasharaEllipsometry and Polarized Light (North-Holland, 1987).
  13. Thin Film Companion—SemiconSoft, Incorporated, Southborough, Mass. 01772, USA.
  14. Picometer Ellipsometer—Beaglehole Instruments, Limited, Wellington, New Zealand.

2004 (1)

1999 (1)

F. Bréhat, B. Wyncke, and A. M. Benoit, “Method for birefringence measurements as a function of wavelength in the visible range, applied to the reinvestigation of crystal quartz,” J. Phys. D: Appl. Phys. 32, 227–233 (1999).
[CrossRef]

1994 (1)

L. Schrottke and G. Jungk, “Automated null ellipsometer with rotating analyzer,” Rev. Sci. Instrum. 65, 3657–3660 (1994).
[CrossRef]

1982 (1)

1980 (1)

M. Yamamoto and O. S. Heavens, “A vacuum automatic ellipsometer for principal angle of incidence measurement,” Surf. Sci. 96, 202–216 (1980).
[CrossRef]

1976 (1)

1974 (2)

M. Yamamoto, “New type of precision ellipsometer without employing a compensator,” Opt. Commun. 10, 200–202 (1974).
[CrossRef]

D. E. Aspnes, “Optimizing precision of rotating-analyzer ellipsometers,” J. Opt. Soc. Am. 64, 639–646 (1974).
[CrossRef]

1952 (1)

J. F. Archard, P. L. Clegg, and A. M. Taylor, “Photoelectric analysis of elliptically polarized light,” Proc. Phys. Soc. Lond. B 65, 758–768 (1952).
[CrossRef]

1936 (1)

1830 (1)

D. Brewster, “On the phenomena and laws of elliptic polarization, as exhibited in the action of metals upon light,” Phil. Trans. Royal Soc. 120, 287–326 (1830).
[CrossRef]

Archard, J. F.

J. F. Archard, P. L. Clegg, and A. M. Taylor, “Photoelectric analysis of elliptically polarized light,” Proc. Phys. Soc. Lond. B 65, 758–768 (1952).
[CrossRef]

Aspnes, D. E.

Azzam, R. M. A.

R. M. A. Azzam and N. M. BasharaEllipsometry and Polarized Light (North-Holland, 1987).

Bashara, N. M.

R. M. A. Azzam and N. M. BasharaEllipsometry and Polarized Light (North-Holland, 1987).

Benoit, A. M.

F. Bréhat, B. Wyncke, and A. M. Benoit, “Method for birefringence measurements as a function of wavelength in the visible range, applied to the reinvestigation of crystal quartz,” J. Phys. D: Appl. Phys. 32, 227–233 (1999).
[CrossRef]

Bréhat, F.

F. Bréhat, B. Wyncke, and A. M. Benoit, “Method for birefringence measurements as a function of wavelength in the visible range, applied to the reinvestigation of crystal quartz,” J. Phys. D: Appl. Phys. 32, 227–233 (1999).
[CrossRef]

Brewster, D.

D. Brewster, “On the phenomena and laws of elliptic polarization, as exhibited in the action of metals upon light,” Phil. Trans. Royal Soc. 120, 287–326 (1830).
[CrossRef]

Candela, G. A.

Chandler-Horowitz, D.

Clegg, P. L.

J. F. Archard, P. L. Clegg, and A. M. Taylor, “Photoelectric analysis of elliptically polarized light,” Proc. Phys. Soc. Lond. B 65, 758–768 (1952).
[CrossRef]

Heavens, O. S.

M. Yamamoto and O. S. Heavens, “A vacuum automatic ellipsometer for principal angle of incidence measurement,” Surf. Sci. 96, 202–216 (1980).
[CrossRef]

Jungk, G.

L. Schrottke and G. Jungk, “Automated null ellipsometer with rotating analyzer,” Rev. Sci. Instrum. 65, 3657–3660 (1994).
[CrossRef]

O’Bryan, H. M.

Schrottke, L.

L. Schrottke and G. Jungk, “Automated null ellipsometer with rotating analyzer,” Rev. Sci. Instrum. 65, 3657–3660 (1994).
[CrossRef]

Takahashi, H.

Taylor, A. M.

J. F. Archard, P. L. Clegg, and A. M. Taylor, “Photoelectric analysis of elliptically polarized light,” Proc. Phys. Soc. Lond. B 65, 758–768 (1952).
[CrossRef]

Wyncke, B.

F. Bréhat, B. Wyncke, and A. M. Benoit, “Method for birefringence measurements as a function of wavelength in the visible range, applied to the reinvestigation of crystal quartz,” J. Phys. D: Appl. Phys. 32, 227–233 (1999).
[CrossRef]

Yamaguchi, T.

Yamamoto, M.

M. Yamamoto and O. S. Heavens, “A vacuum automatic ellipsometer for principal angle of incidence measurement,” Surf. Sci. 96, 202–216 (1980).
[CrossRef]

M. Yamamoto, “New type of precision ellipsometer without employing a compensator,” Opt. Commun. 10, 200–202 (1974).
[CrossRef]

Appl. Opt. (2)

J. Opt. Soc. Am. (2)

J. Opt. Soc. Am. A (1)

J. Phys. D: Appl. Phys. (1)

F. Bréhat, B. Wyncke, and A. M. Benoit, “Method for birefringence measurements as a function of wavelength in the visible range, applied to the reinvestigation of crystal quartz,” J. Phys. D: Appl. Phys. 32, 227–233 (1999).
[CrossRef]

Opt. Commun. (1)

M. Yamamoto, “New type of precision ellipsometer without employing a compensator,” Opt. Commun. 10, 200–202 (1974).
[CrossRef]

Phil. Trans. Royal Soc. (1)

D. Brewster, “On the phenomena and laws of elliptic polarization, as exhibited in the action of metals upon light,” Phil. Trans. Royal Soc. 120, 287–326 (1830).
[CrossRef]

Proc. Phys. Soc. Lond. B (1)

J. F. Archard, P. L. Clegg, and A. M. Taylor, “Photoelectric analysis of elliptically polarized light,” Proc. Phys. Soc. Lond. B 65, 758–768 (1952).
[CrossRef]

Rev. Sci. Instrum. (1)

L. Schrottke and G. Jungk, “Automated null ellipsometer with rotating analyzer,” Rev. Sci. Instrum. 65, 3657–3660 (1994).
[CrossRef]

Surf. Sci. (1)

M. Yamamoto and O. S. Heavens, “A vacuum automatic ellipsometer for principal angle of incidence measurement,” Surf. Sci. 96, 202–216 (1980).
[CrossRef]

Other (3)

R. M. A. Azzam and N. M. BasharaEllipsometry and Polarized Light (North-Holland, 1987).

Thin Film Companion—SemiconSoft, Incorporated, Southborough, Mass. 01772, USA.

Picometer Ellipsometer—Beaglehole Instruments, Limited, Wellington, New Zealand.

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Figures (3)

Fig. 1
Fig. 1

Schematic of the autocollimating null ellipsometer: 405 / 488 nm , 405 nm , and 488 nm lasers: He–Ne, tunable He–Ne laser; FM, “flipper” mirror mount; BS, beam splitter; P, polarizer; SBC, Soleil–Babinet compensator; S, sample; G, goniometer; M, mirror; PD, photodetector.

Fig. 2
Fig. 2

Measured values of ψ and Δ at variable angles of incidence for a thick gold film at λ = 632.8 nm .

Fig. 3
Fig. 3

Measured values of ψ and Δ at 70 ° and 75 ° AOI for a 100 nm Si O 2 film on a silicon wafer.

Tables (1)

Tables Icon

Table 1 Comparison of Measured Si O 2 Film Thickness

Equations (7)

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[ r p 0 0 r s ] [ 1 0 0 exp ( i δ ) ] [ cos P sin P ] = 1 2 [ 1 ± i ] , [ r p cos P r s exp ( i δ ) sin P ] = 1 2 [ 1 ± i ] .
tan P tan ψ exp [ i ( δ + Δ ) ] = exp [ ± i π 2 ] .
P = ± ψ ,
δ + Δ = ± k π 2 ,
δ 632.8 = ( 28.657 ± 0.002 ) × m 2.050 ,
δ λ = δ 632.8 × 632.8 λ × Δ n λ Δ n 632.8 ,
Δ n λ × 10 3 = 8.973 + 6.983 × 10 4 λ 2 + 5.370 × 10 9 λ 4 3.079 × 10 7 × λ 2 ,

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