Abstract

A problem with conventional techniques of interference microscopy, when profiling surfaces with an extended range of heights, is that only points on a single plane are in sharp focus. Other points, which are higher or lower, may be out of focus, with a consequent loss of lateral resolution. We show that white-light interference microscopy, with an achromatic phase-shifter, makes it possible to produce a three-dimensional representation of such surfaces with high lateral resolution over the entire range of heights.

© 2006 Optical Society of America

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References

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  1. Y.-Y. Cheng and J. C. Wyant, "Two-wavelength phase shifting interferometry," Appl. Opt. 23, 4539-4543 (1984).
    [CrossRef] [PubMed]
  2. Y.-Y. Cheng and J. C. Wyant, "Multiple-wavelength phase shifting interferometry," Appl. Opt. 24, 804-807 (1985).
    [CrossRef] [PubMed]
  3. K. Creath, "Step height measurement using two-wavelength phase-shifting interferometry," Appl. Opt. 26, 2810-2816 (1987).
    [CrossRef] [PubMed]
  4. S. S. C. Chim and G. S. Kino, "Correlation microscope," Opt Lett. 15, 579-581 (1990).
    [CrossRef] [PubMed]
  5. B. S. Lee and T. C. Strand, "Profilometry with a coherence scanning microscope," Appl. Opt. 29, 3784-3788 (1990).
    [CrossRef] [PubMed]
  6. P. Hariharan and M. Roy, "White-light phase-stepping interferometry for surface profiling," J. Mod. Opt. 41, 2197-2201 (1994).
    [CrossRef]
  7. P. Hariharan and M. Roy, "White-light phase-stepping interferometry: measurement of the fractional interference order," J. Mod. Opt. 42, 2357-2360 (1995).
    [CrossRef]
  8. M. Roy, C. J. R. Sheppard, and P. Hariharan, "Low-coherence interference microscopy using a ferro-electric liquid crystal phase-modulator," Opt. Express. 12, 2512-2516 (2004).
    [CrossRef] [PubMed]
  9. P. Hariharan, P. E. Ciddor, and M. Roy, "Improved switchable achromatic phase shifters 2," Opt. Eng. 44, 105603/1-105603/4 (2005).
    [CrossRef]
  10. M. Roy, G. Cox, and P. Hariharan, "Low-coherence interference microscopy with an improved switchable achromatic phase- shifter," Opt. Express. 13, 9125-9130 (2005).
    [CrossRef] [PubMed]

2005 (1)

M. Roy, G. Cox, and P. Hariharan, "Low-coherence interference microscopy with an improved switchable achromatic phase- shifter," Opt. Express. 13, 9125-9130 (2005).
[CrossRef] [PubMed]

2004 (1)

M. Roy, C. J. R. Sheppard, and P. Hariharan, "Low-coherence interference microscopy using a ferro-electric liquid crystal phase-modulator," Opt. Express. 12, 2512-2516 (2004).
[CrossRef] [PubMed]

1995 (1)

P. Hariharan and M. Roy, "White-light phase-stepping interferometry: measurement of the fractional interference order," J. Mod. Opt. 42, 2357-2360 (1995).
[CrossRef]

1994 (1)

P. Hariharan and M. Roy, "White-light phase-stepping interferometry for surface profiling," J. Mod. Opt. 41, 2197-2201 (1994).
[CrossRef]

1990 (2)

1987 (1)

1985 (1)

1984 (1)

Cheng, Y.-Y.

Chim, S. S. C.

S. S. C. Chim and G. S. Kino, "Correlation microscope," Opt Lett. 15, 579-581 (1990).
[CrossRef] [PubMed]

Cox, G.

M. Roy, G. Cox, and P. Hariharan, "Low-coherence interference microscopy with an improved switchable achromatic phase- shifter," Opt. Express. 13, 9125-9130 (2005).
[CrossRef] [PubMed]

Creath, K.

Hariharan, P.

M. Roy, G. Cox, and P. Hariharan, "Low-coherence interference microscopy with an improved switchable achromatic phase- shifter," Opt. Express. 13, 9125-9130 (2005).
[CrossRef] [PubMed]

M. Roy, C. J. R. Sheppard, and P. Hariharan, "Low-coherence interference microscopy using a ferro-electric liquid crystal phase-modulator," Opt. Express. 12, 2512-2516 (2004).
[CrossRef] [PubMed]

P. Hariharan and M. Roy, "White-light phase-stepping interferometry: measurement of the fractional interference order," J. Mod. Opt. 42, 2357-2360 (1995).
[CrossRef]

P. Hariharan and M. Roy, "White-light phase-stepping interferometry for surface profiling," J. Mod. Opt. 41, 2197-2201 (1994).
[CrossRef]

Kino, G. S.

S. S. C. Chim and G. S. Kino, "Correlation microscope," Opt Lett. 15, 579-581 (1990).
[CrossRef] [PubMed]

Lee, B. S.

Roy, M.

M. Roy, G. Cox, and P. Hariharan, "Low-coherence interference microscopy with an improved switchable achromatic phase- shifter," Opt. Express. 13, 9125-9130 (2005).
[CrossRef] [PubMed]

M. Roy, C. J. R. Sheppard, and P. Hariharan, "Low-coherence interference microscopy using a ferro-electric liquid crystal phase-modulator," Opt. Express. 12, 2512-2516 (2004).
[CrossRef] [PubMed]

P. Hariharan and M. Roy, "White-light phase-stepping interferometry: measurement of the fractional interference order," J. Mod. Opt. 42, 2357-2360 (1995).
[CrossRef]

P. Hariharan and M. Roy, "White-light phase-stepping interferometry for surface profiling," J. Mod. Opt. 41, 2197-2201 (1994).
[CrossRef]

Sheppard, C. J. R.

M. Roy, C. J. R. Sheppard, and P. Hariharan, "Low-coherence interference microscopy using a ferro-electric liquid crystal phase-modulator," Opt. Express. 12, 2512-2516 (2004).
[CrossRef] [PubMed]

Strand, T. C.

Wyant, J. C.

Appl. Opt. (4)

J. Mod. Opt. (2)

P. Hariharan and M. Roy, "White-light phase-stepping interferometry for surface profiling," J. Mod. Opt. 41, 2197-2201 (1994).
[CrossRef]

P. Hariharan and M. Roy, "White-light phase-stepping interferometry: measurement of the fractional interference order," J. Mod. Opt. 42, 2357-2360 (1995).
[CrossRef]

Opt Lett. (1)

S. S. C. Chim and G. S. Kino, "Correlation microscope," Opt Lett. 15, 579-581 (1990).
[CrossRef] [PubMed]

Opt. Express. (2)

M. Roy, C. J. R. Sheppard, and P. Hariharan, "Low-coherence interference microscopy using a ferro-electric liquid crystal phase-modulator," Opt. Express. 12, 2512-2516 (2004).
[CrossRef] [PubMed]

M. Roy, G. Cox, and P. Hariharan, "Low-coherence interference microscopy with an improved switchable achromatic phase- shifter," Opt. Express. 13, 9125-9130 (2005).
[CrossRef] [PubMed]

Other (1)

P. Hariharan, P. E. Ciddor, and M. Roy, "Improved switchable achromatic phase shifters 2," Opt. Eng. 44, 105603/1-105603/4 (2005).
[CrossRef]

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Figures (4)

Fig. 1.
Fig. 1.

Variation of the diameter of the circle of confusion with the distance from the plane of best focus for microscope objectives with: (a) 0.80 NA (50× magnification), (b) 0.65 NA (40× magnification) and (c) 0.25 NA (10× magnification).

Fig. 2.
Fig. 2.

Three-dimensional image of the surface of a section of an integrated circuit (lateral dimensions 59μm×44 μm) tilted so that the left edge was approximately 1.8μm above the center of the sample, while the right edge was approximately 1.8μm below the center of the sample.

Fig. 3.
Fig. 3.

Profiles of the surface of the test sample: (a) along a line in a plane of best focus, and (b) along a line in a plane 1.8 μm below the plane of best focus.

Fig. 4.
Fig. 4.

Photograph of the tilted test sample recorded under the same conditions.

Equations (2)

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V = [ ( I 90 I 90 ) 2 + 2 ( I 0 I 90 I 90 ) I 90 + I 90 ] .
tan ϕ = I 90 I 90 2 I 0 I 90 I 90

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