Abstract

We propose an optical thin-film characterization technique, differential optical sectioning interference microscopy (DOSIM), for simultaneously measuring the refractive indices and thicknesses of transparent thin films with submicrometer lateral resolution. DOSIM obtains the depth and optical phase information of a thin film by using a dual-scan concept in differential optical sectioning microscopy combined with the Fabry–Perot interferometric effect and allows the solution of refractive index and thickness without the 2π phase-wrapping ambiguity. Because DOSIM uses a microscope objective as the probe, its lateral resolution achieves the diffraction limit. As a demonstration, we measure the refractive indices and thicknesses of SiO2 thin films grown on Si substrate and indium-tin-oxide thin films grown on a glass substrate. We also compare the measurement results of DOSIM with those of a conventional ellipsometer and an atomic force microscope.

© 2007 Optical Society of America

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References

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  1. R. M. A. Azzam and N. M. Bashara, Ellipsometry and Polarized Light (North-Holland, Amsterdam, 1987).
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  8. C.-H. Lee, H.-Y. Mong, and W.-C. Lin, "Noninterferometric wide-field optical profilometry with nanometer depth resolution," Opt. Lett. 27, 1773-1775 (2002).
    [CrossRef]
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    [CrossRef]

2005

2002

1999

1998

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

1997

M. A. A. Neil, R. Juskaitis, and T. Wilson, "Method of obtaining optical sectioning by using structured light in a conventional microscope," Opt. Lett. 22, 1905-1907 (1997).
[CrossRef]

C.-H. Lee and J. Wang, "Noninterferometric differential confocal microscopy with 2 nm depth resolution," Opt. Commun. 135, 233-237 (1997).
[CrossRef]

1994

Albersdorfer, A.

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

Azzam, R. M. A.

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

Bashara, N. M.

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

Elender, G.

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

Juskaitis, R.

Lee, C.-H.

Leger, J. R.

Lin, J.-Y.

Lin, W.-C.

Liu, A.-H.

Mathe, G.

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

Mong, H.-Y.

Neil, M. A. A.

Neumaier, K. R.

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

Otsuki, S.

Paduschek, P.

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

Plawsky, J. L.

Sackmann, E.

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

Tamada, K.

Tsai, C.-W.

Wakida, S.-I.

Wang, C.-C.

Wang, J.

C.-W. Tsai, C.-H. Lee, and J. Wang, "Deconvolution of local surface response from topography in nanometer profilometry with a dual-scan method," Opt. Lett. 24, 1732-1734 (1999).
[CrossRef]

C.-H. Lee and J. Wang, "Noninterferometric differential confocal microscopy with 2 nm depth resolution," Opt. Commun. 135, 233-237 (1997).
[CrossRef]

Wayner, P. C.

Wilson, T.

Zhan, Q.

Appl. Opt.

Appl. Phys. Lett.

A. Albersdorfer, G. Elender, G. Mathe, K. R. Neumaier, P. Paduschek, and E. Sackmann, "High resolution imaging microellipsometry of soft surfaces at 3 μm lateral and 5 Å normal resolution," Appl. Phys. Lett. 72, 2930-2932 (1998).
[CrossRef]

Opt. Commun.

C.-H. Lee and J. Wang, "Noninterferometric differential confocal microscopy with 2 nm depth resolution," Opt. Commun. 135, 233-237 (1997).
[CrossRef]

Opt. Express

Opt. Lett.

Other

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

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Figures (4)

Fig. 1
Fig. 1

(a) Setup of the DOSIM system. (b) Linear region of the axial response curve of our DOSIM system. The slope ( α ) of the fitting straight line is 1.03 μ m 1 .

Fig. 2
Fig. 2

(a) Bright-field image of a 12 μ m wide SiO 2 stripe grown on Si substrate. The contrast has been enhanced by histogram stretching. (b) Topography of this SiO 2 stripe measured by DOSIM. (c) Line profiles of this SiO 2 stripe measured by DOSIM and AFM. The two profiles may not be exactly on the same position.

Fig. 3
Fig. 3

(a) Bright-field image of an ITO thin film coated on glass substrate. The contrast has been enhanced by histogram stretching. (b) Topography of this ITO film measured by DOSIM. (c) Line profiles of this ITO film measured by DOSIM and AFM. The two profiles may not be exactly on the same position.

Fig. 4
Fig. 4

(a) Bright-field image of a 300 nm SiO 2 film grown on Si substrate. The contrast has been enhanced by histogram stretching. (b) Topography of this SiO 2 film measured by DOSIM. (c) Profiles of this SiO 2 film measured by DOSIM and a stylus surface profiler (Alpha-Step).

Equations (4)

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I r ( n 2 , d ) | E 0 e j ω t ( r 1 + r 2 e j δ 1 + r 1 r 2 e j δ ) | 2
I 0 ( | r 1 | 2 + r 1 r 2 * e j δ + r 1 * r 2 e j δ + | r 2 | 2 1 + r 1 * r 2 * e j δ + r 1 r 2 e j δ + | r 1 | 2 | r 2 | 2 ) ,
I DOSIM ( n 2 , d )
= I 0 ( | r 1 | 2 T 1 2 + r 1 r 2 * T 1 T e j δ + r 1 * r 2 T 1 T e j δ + | r 2 | 2 T 2 1 + r 1 * r 2 * e j δ + r 1 r 2 e j δ + | r 1 | 2 | r 2 | 2 ) ,

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