Abstract

As an extension of the authors’ previous report of Ref 1, we describe an improved version of dispersive white-light interferometry that enables us to measure the tomographical thickness profile of a thin-film layer through Fourier-transform analysis of spectrally-resolved interference signals. The group refractive index can also be determined without prior knowledge of the geometrical thickness of the film layer. Owing to fast measurement speed with no need of mechanical depth scanning, the proposed method is well suited for in-line 3-D inspection of dielectric thinfilm layers particularly for the semiconductor and flat-panel display industry.

© 2006 Optical Society of America

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References

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  1. Y.-S. Ghim and S.-W. Kim, "Dispersive white-light interferometry for thin-film thickness profile measurement," in Optical Measurement Systems for Industrial Inspection IV, W. Osten, C. Gorecki, and E. L. Novak, eds., in Proc. SPIE 5856, 419-426 (2005).
    [CrossRef]
  2. P. De Groot and L. Deck, "Three-dimensional imaging by sub-Nyquist sampling of white-light interferograms," Opt. Lett. 18, 1462-1464 (1993).
    [CrossRef] [PubMed]
  3. S. Kuwamura and I. Yamaguchi, "Wavelength scanning profilometry for real-time surface shape measurement," Appl. Opt. 36, 4473-4482 (1997).
    [CrossRef] [PubMed]
  4. D. S. Mehta, S. Saito, H. Hinosugi, M. Takeda, and T. Kurosawa, "Spectral interference mirau microscope with an acousto-optic tunable filter for three-dimensional surface profilometry," Appl. Opt. 42, 1296-1305 (2003).
    [CrossRef] [PubMed]
  5. M. Kinoshita, M. Takeda, H. Yago, Y. Watanabe, and T. Kurokawa, "Optical frequency-domain imaging microprofilometry with a frequency-tunable liquid-crystal Fabry-Perot etalon device," Appl. Opt. 38, 7063-7068 (1999).
    [CrossRef]
  6. J. Schwider and L. Zhou, "Dispersive interferometric profiler," Opt. Lett. 19, 995-997 (1994).
    [CrossRef] [PubMed]
  7. U. Schnell, E. Zimmermann, and R. Dändliker, "Absolute distance measurement with synchronously sampled white-light channeled spectrum interferometry," Pure Appl. Opt. 4, 643-651(1995).Q1
    [CrossRef]
  8. S.-W. Kim and G.-H. Kim, "Thickness-profile measurement of transparent thin-film layers by white-light scanning interferometry," Appl. Opt. 38, 5968-5973(1999).
    [CrossRef]
  9. D. Kim, S. Kim, H. J. Kong and Y. Lee, "Measurement of the thickness profile of a transparent thin-film deposited upon a pattern structure with an acousto-optic tunable filter," Opt. Lett. 27, 1893-1895 (2002).
    [CrossRef]
  10. U. Schnell, R. Dändliker and S. Gray, "Dispersive white-light interferometry for absolute distance measurement with dielectric multilayer systems on the target," Opt. Lett,  21, 528-530 (1996).
    [CrossRef] [PubMed]
  11. K.-N. Joo and S.-W. Kim, "Absolute distance measurement by dispersive interferometry using a femtosecond pulse laser," Opt. Express 14, 5954-5960 (2006).
    [CrossRef] [PubMed]

2006

2003

2002

1999

1997

1996

U. Schnell, R. Dändliker and S. Gray, "Dispersive white-light interferometry for absolute distance measurement with dielectric multilayer systems on the target," Opt. Lett,  21, 528-530 (1996).
[CrossRef] [PubMed]

1995

U. Schnell, E. Zimmermann, and R. Dändliker, "Absolute distance measurement with synchronously sampled white-light channeled spectrum interferometry," Pure Appl. Opt. 4, 643-651(1995).Q1
[CrossRef]

1994

1993

Dändliker, R.

U. Schnell, R. Dändliker and S. Gray, "Dispersive white-light interferometry for absolute distance measurement with dielectric multilayer systems on the target," Opt. Lett,  21, 528-530 (1996).
[CrossRef] [PubMed]

U. Schnell, E. Zimmermann, and R. Dändliker, "Absolute distance measurement with synchronously sampled white-light channeled spectrum interferometry," Pure Appl. Opt. 4, 643-651(1995).Q1
[CrossRef]

De Groot, P.

Deck, L.

Gray, S.

U. Schnell, R. Dändliker and S. Gray, "Dispersive white-light interferometry for absolute distance measurement with dielectric multilayer systems on the target," Opt. Lett,  21, 528-530 (1996).
[CrossRef] [PubMed]

Hinosugi, H.

Joo, K.-N.

Kim, D.

Kim, G.-H.

Kim, S.

Kim, S.-W.

Kinoshita, M.

Kong, H. J.

Kurokawa, T.

Kurosawa, T.

Kuwamura, S.

Lee, Y.

Mehta, D. S.

Saito, S.

Schnell, U.

U. Schnell, R. Dändliker and S. Gray, "Dispersive white-light interferometry for absolute distance measurement with dielectric multilayer systems on the target," Opt. Lett,  21, 528-530 (1996).
[CrossRef] [PubMed]

U. Schnell, E. Zimmermann, and R. Dändliker, "Absolute distance measurement with synchronously sampled white-light channeled spectrum interferometry," Pure Appl. Opt. 4, 643-651(1995).Q1
[CrossRef]

Schwider, J.

Takeda, M.

Watanabe, Y.

Yago, H.

Yamaguchi, I.

Zhou, L.

Zimmermann, E.

U. Schnell, E. Zimmermann, and R. Dändliker, "Absolute distance measurement with synchronously sampled white-light channeled spectrum interferometry," Pure Appl. Opt. 4, 643-651(1995).Q1
[CrossRef]

Appl. Opt.

Opt. Express

Opt. Lett

U. Schnell, R. Dändliker and S. Gray, "Dispersive white-light interferometry for absolute distance measurement with dielectric multilayer systems on the target," Opt. Lett,  21, 528-530 (1996).
[CrossRef] [PubMed]

Opt. Lett.

Pure Appl. Opt.

U. Schnell, E. Zimmermann, and R. Dändliker, "Absolute distance measurement with synchronously sampled white-light channeled spectrum interferometry," Pure Appl. Opt. 4, 643-651(1995).Q1
[CrossRef]

Other

Y.-S. Ghim and S.-W. Kim, "Dispersive white-light interferometry for thin-film thickness profile measurement," in Optical Measurement Systems for Industrial Inspection IV, W. Osten, C. Gorecki, and E. L. Novak, eds., in Proc. SPIE 5856, 419-426 (2005).
[CrossRef]

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Figures (5)

Fig. 1
Fig. 1

Optical configuration of dispersive white-light interferometry; LP: linear polarizer, BS: beam splitter, PBS: polarizing beam splitter, ES: entrance slit, DG: dispersive grating, CCD: charge coupled device.

Fig. 2
Fig. 2

Unfolded diagram depicting four major groups of spectrally-resolved interference signals between the reference and specimen. The reference beam is shown in blue and the multireflected beams from the specimen are in red. The parameter h denotes the distance between the reference mirror and the top surface, and d is the thickness of the thin-film layer.

Fig. 3
Fig. 3

Interference signals G(ν) vs. Fourier-transforms Γ(τ): (a) interference signal from Spectrometer T, (b) Fourier-Transform of (a), (c) interference signal from Spectrometer S, (d) Fourier-Transform of (c), (e) subtracted interference signal, and (f) Fourier-Transform of(e).

Fig. 4
Fig. 4

Group refractive index measurement using a stepped film layer: (a) top view of a stepped SiO2 thin-film layer and (b) its cross sectional view of line A-A’.

Fig. 5
Fig. 5

Exemplary measurement results: (a) 3-D thickness profile of ‘0” patterned SiO2 film layer on flat Si substrate, (b) cross sectional profile of (a), (c) 3-D thickness profile on patterned Si substrate, and (d) cross sectional profile of (c).

Equations (5)

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G ( v ) = G rr ( v ) + n = 0 G nn ( v )
+ n = 0 G nr ( v ) cos [ 2 π ( τ h + n τ d ) v ] + n = 0 m n G nm ( v ) cos [ 2 π ( n m ) τ d v ]
FG ( v ) = Γ rr ( τ ) + n = 0 Γ nn ( τ )
+ n = 0 Γ nr [ τ + ( τ h + n τ d ) ] + n = 0 Γ nr [ τ ( τ h + n τ d ) ]
+ n = 0 m n Γ nm [ τ + ( n m ) τ d ) ] + n = 0 m n Γ nm [ τ ( n m ) τ d ) ]

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