Abstract

We report on a novel microellipsometer that uses a spatially filtered high-numerical-aperture (NA) lens for large-angle ellipsometric illumination and high spatial resolution. A radially symmetric ellipsometric signal is achieved with two half-wave plates to produce a pure polarization rotation and a birefringent cube as a radial analyzer. This radial symmetry offers a better signal-to-noise ratio compared with other microellipsometer techniques. Ellipsometric measurement with a spatial resolution of 0.5 µm is performed with a He-Ne (632.8-nm) laser source and an objective lens with an NA of 0.8. Experimental data on SiO2 samples with different thicknesses are in good agreement with spectroscopic ellipsometer results. We acquired ellipsometric images of photoresist microstructure through scanning the sample. Surface profiles of the photoresist microstructure are derived from the ellipsometric data and compared with the results from a stylus profiler.

© 2002 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef] [PubMed]
  5. V. G. Niziev, A. V. Nesterov, “Influence of beam polarization on laser cutting efficiency,” J. Phys. D. 32, 1455–1461 (1999).
    [CrossRef]
  6. C. Ye, “Non mechanical half-wave plate polarization rotator,” Optik 101, 77–79 (1995).
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  8. D. P. Biss, T. G. Brown, “Cylindrical vector beam focusing through a dielectric interface,” Opt. Exp. 9, 490–497 (2001), http://www.opticsexpress.org .
    [CrossRef]
  9. R. Oron, S. Blit, N. Davidson, A. A. Friesem, “The formation of laser beams with pure azimuthal or radial polarization,” Appl. Phys. Lett. 77, 3322–3324 (2000).
    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef]
  12. S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
    [CrossRef]

2001 (2)

D. P. Biss, T. G. Brown, “Cylindrical vector beam focusing through a dielectric interface,” Opt. Exp. 9, 490–497 (2001), http://www.opticsexpress.org .
[CrossRef]

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “The focus of light—theoretical calculation and experimental tomographic reconstruction,” Appl. Phys. B 72, 109–113 (2001).
[CrossRef]

2000 (2)

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
[CrossRef]

R. Oron, S. Blit, N. Davidson, A. A. Friesem, “The formation of laser beams with pure azimuthal or radial polarization,” Appl. Phys. Lett. 77, 3322–3324 (2000).
[CrossRef]

1999 (1)

V. G. Niziev, A. V. Nesterov, “Influence of beam polarization on laser cutting efficiency,” J. Phys. D. 32, 1455–1461 (1999).
[CrossRef]

1998 (1)

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

1996 (2)

1995 (1)

C. Ye, “Non mechanical half-wave plate polarization rotator,” Optik 101, 77–79 (1995).

1994 (1)

1986 (1)

M. Erman, J. B. Theeten, “Spatially resolved ellipsometry,” J. Appl. Phys. 60, 859–873 (1986).
[CrossRef]

Azzam, R. M. A.

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

Bashara, N. M.

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

Biss, D. P.

D. P. Biss, T. G. Brown, “Cylindrical vector beam focusing through a dielectric interface,” Opt. Exp. 9, 490–497 (2001), http://www.opticsexpress.org .
[CrossRef]

Blit, S.

R. Oron, S. Blit, N. Davidson, A. A. Friesem, “The formation of laser beams with pure azimuthal or radial polarization,” Appl. Phys. Lett. 77, 3322–3324 (2000).
[CrossRef]

Brown, T. G.

D. P. Biss, T. G. Brown, “Cylindrical vector beam focusing through a dielectric interface,” Opt. Exp. 9, 490–497 (2001), http://www.opticsexpress.org .
[CrossRef]

Chen, J.

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

Davidson, N.

R. Oron, S. Blit, N. Davidson, A. A. Friesem, “The formation of laser beams with pure azimuthal or radial polarization,” Appl. Phys. Lett. 77, 3322–3324 (2000).
[CrossRef]

Dorn, R.

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “The focus of light—theoretical calculation and experimental tomographic reconstruction,” Appl. Phys. B 72, 109–113 (2001).
[CrossRef]

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
[CrossRef]

Eberler, M.

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “The focus of light—theoretical calculation and experimental tomographic reconstruction,” Appl. Phys. B 72, 109–113 (2001).
[CrossRef]

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
[CrossRef]

Erman, M.

M. Erman, J. B. Theeten, “Spatially resolved ellipsometry,” J. Appl. Phys. 60, 859–873 (1986).
[CrossRef]

Fanton, J.

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

Friesem, A. A.

R. Oron, S. Blit, N. Davidson, A. A. Friesem, “The formation of laser beams with pure azimuthal or radial polarization,” Appl. Phys. Lett. 77, 3322–3324 (2000).
[CrossRef]

Glöckl, O.

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “The focus of light—theoretical calculation and experimental tomographic reconstruction,” Appl. Phys. B 72, 109–113 (2001).
[CrossRef]

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
[CrossRef]

Holmes, R. D.

Leng, J. M.

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

Leuchs, G.

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “The focus of light—theoretical calculation and experimental tomographic reconstruction,” Appl. Phys. B 72, 109–113 (2001).
[CrossRef]

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
[CrossRef]

Liu, A.-H.

Nesterov, A. V.

V. G. Niziev, A. V. Nesterov, “Influence of beam polarization on laser cutting efficiency,” J. Phys. D. 32, 1455–1461 (1999).
[CrossRef]

Niziev, V. G.

V. G. Niziev, A. V. Nesterov, “Influence of beam polarization on laser cutting efficiency,” J. Phys. D. 32, 1455–1461 (1999).
[CrossRef]

Opsal, J.

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

Oron, R.

R. Oron, S. Blit, N. Davidson, A. A. Friesem, “The formation of laser beams with pure azimuthal or radial polarization,” Appl. Phys. Lett. 77, 3322–3324 (2000).
[CrossRef]

Plawsky, J. L.

Quabis, S.

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “The focus of light—theoretical calculation and experimental tomographic reconstruction,” Appl. Phys. B 72, 109–113 (2001).
[CrossRef]

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
[CrossRef]

Ritz, K.

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

Schadt, M.

See, C. W.

Senko, M.

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

Somekh, M. G.

Stalder, M.

Theeten, J. B.

M. Erman, J. B. Theeten, “Spatially resolved ellipsometry,” J. Appl. Phys. 60, 859–873 (1986).
[CrossRef]

Wayner, P. C.

Ye, C.

C. Ye, “Non mechanical half-wave plate polarization rotator,” Optik 101, 77–79 (1995).

Appl. Opt. (2)

Appl. Phys. B (1)

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “The focus of light—theoretical calculation and experimental tomographic reconstruction,” Appl. Phys. B 72, 109–113 (2001).
[CrossRef]

Appl. Phys. Lett. (1)

R. Oron, S. Blit, N. Davidson, A. A. Friesem, “The formation of laser beams with pure azimuthal or radial polarization,” Appl. Phys. Lett. 77, 3322–3324 (2000).
[CrossRef]

J. Appl. Phys. (1)

M. Erman, J. B. Theeten, “Spatially resolved ellipsometry,” J. Appl. Phys. 60, 859–873 (1986).
[CrossRef]

J. Phys. D. (1)

V. G. Niziev, A. V. Nesterov, “Influence of beam polarization on laser cutting efficiency,” J. Phys. D. 32, 1455–1461 (1999).
[CrossRef]

Opt. Commun. (1)

S. Quabis, R. Dorn, M. Eberler, O. Glöckl, G. Leuchs, “Focusing light into a tighter spot,” Opt. Commun. 179, 1–7 (2000).
[CrossRef]

Opt. Exp. (1)

D. P. Biss, T. G. Brown, “Cylindrical vector beam focusing through a dielectric interface,” Opt. Exp. 9, 490–497 (2001), http://www.opticsexpress.org .
[CrossRef]

Opt. Lett. (1)

Optik (1)

C. Ye, “Non mechanical half-wave plate polarization rotator,” Optik 101, 77–79 (1995).

Thin Solid Films (1)

J. M. Leng, J. Chen, J. Fanton, M. Senko, K. Ritz, J. Opsal, “Characterization of titanium nitride (TiN) films on various substrates using spectrophotometry, beam profile reflectometry, beam profile ellipsometry and spectroscopic beam profile ellipsometry,” Thin Solid Films 313–314, 308–313 (1998).
[CrossRef]

Other (1)

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

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Figures (11)

Fig. 1
Fig. 1

Design principle of a radially symmetric microellipsometer. (a) Conventional ellipsometer. (b) Insertion of lens. A single ray path represents a conventional ellipsometer channel. (c) A radially symmetric microellipsometer when we continuously repeat the single channel of (b) in a radially symmetric manner.

Fig. 2
Fig. 2

Schematic of a radially symmetric microellipsometer design.

Fig. 3
Fig. 3

Schematic of the two half-wave plates polarization rotator. E i and E f are the initial and final state of polarization. C 1 and C 2 represent the fast axes of the first and the second half-wave-plate. θ1 and θ2 are the angular position of C 1 and C 2 with respect to E i . The first half-wave plate rotates E i by 2θ1 to an intermediate state of polarization (dashed line). The second half-wave plate further rotates the intermediate polarization by 2(θ2 - 2θ1). The total rotation between E i and E f is 2(θ2 - θ1), which is determined by the angular positions of the two half-wave plates and is independent of the initial state of polarization.

Fig. 4
Fig. 4

Schematic of a radial analyzer with a birefringent lens.

Fig. 5
Fig. 5

(a) Schematic of a radial analyzer with a birefringent cube. (b) Transmission axes of such a radial analyzer.

Fig. 6
Fig. 6

Coordinate systems used in the derivation of a radially symmetric microellipsometer signal.

Fig. 7
Fig. 7

Experimental setup. BS, beam splitter; GPIB, general-purpose interface bus.

Fig. 8
Fig. 8

(a) Theoretical and experimental phase data of SiO2 thin films on silicon. (b) Theoretical and experimental amplitude data of SiO2 thin films on silicon. A small residual birefringence of the objective lens was detected.

Fig. 9
Fig. 9

Ellipsometric images of a photoresist microprism. (a) Phase image. (b) Amplitude image.

Fig. 10
Fig. 10

Surface profile of the photoresist microprism measured by the microellipsometer and a stylus profiler.

Fig. 11
Fig. 11

Schematic of an electro-optical (EO) pure polarization rotator. The fast axes C 1 of the first λ/4 plate and C 3 of the second λ/4 plate are orthogonal. A variable retarder is placed between the two λ/4 plates. The fast axis C 2 of the variable retarder has an angle of π/4 with respect to C 1. The amount of polarization rotation from this device is determined by the retardation of the variable retarder and is independent of the initial state of polarization. LC, liquid crystal.

Equations (19)

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T=R-θ2100-1Rθ2R-θ1100-1Rθ1=cos 2θ2sin 2θ2sin 2θ2-cos 2θ2cos 2θ1sin 2θ1sin 2θ1-cos 2θ1=cos 2θ2-θ1-sin 2θ2-θ1sin 2θ2-θ1cos 2θ2-θ1=R-2θ2-θ1.
Ein=1j.
E=RφEin=cos φsin φ-sin φcos φ1j=expjφ1j.
Eφ=expjφR-θ0cos j sin .
Eφ=R-φEφ=expjφR-θ0+φcos j sin .
Eφ=RFexpjφR-θ0+φcos j sin =expjφRF-θ0+φcos j sin .
Eφ=1000RφexpjφRF-θ0+φcos j sin  =expjφ1000RF-θ0cos j sin  =expjφ×cosF-θ0cos +j sinF-θ0sin 0.
P  02π |Eφ|2dφ=02πcos2F-θ0cos2 +sin2F-θ0sin2 dφ=2πcos2F-θ0cos2 +sin2F-θ0sin2 .
P=K1+cos 2 cos2F-θ0,
R-θ0cos j sin =rs00rp1j=rsjrp,
rprs=tan Ψ expjΔ.
tan2Ψ=sin2 θ0 cos2 +cos2 θ0 sin2 cos2 θ0 cos2 +sin2 θ0 sin2 ,
Δ=tan-1tan tan θ0+tan-1tan θ0 tan -π2.
P=K1+cos 2 cos2F-θ0=K1+cos 2 cos2ωt-θ0.
R=B cos2ωt-θr,
S=KB1+cos 2 cos2ωt-θ0-θecos2ωt-θr=KB cos2ωt-θr+KB cos 2 cos2ωt-θ0-θecos2ωt-θr=KB cos2ωt-θr+KB2cos 2 cos4ωt-2θ0-θe-θr+KB2cos 2 cos2θ0-θe+θr=A1 cos2ωt-θr+A2 cos4ωt-2θ0-θe-θr+A0=A0+A1 cosωrt-θr+A2 cos2ωrt-θs,
cos 2=2A2/A1,
θ0=θs-θe-θr/2.
T=R-π2100-jRπ2R-π4×100exp-jδRπ4100-j =0-110100-j1211-11×100exp-jδ1211-11100-j=-jexp-j δ2Rδ2,

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