Abstract

Two different optical techniques for surface tracking and linewidth measurement are evaluated. First, an evaluation is made of the performance of a double-focus polarization microscope, based on results from a computer model and from experimental measurements. The assessment shows that a phase curvature effect makes the operation of this configuration impractical as a surface tracking device and linewidth measurement system. An alternative arrangement of using a double aperture is evaluated. The phase curvature effect is reduced in this type of microscope. A practical optical arrangement to implement a double-aperture microscope is given.

© 2000 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. N. M. Mason, “Critical dimension measurement of semiconductor features,” Ph.D. dissertation (Department of Electronic and Electrical Engineering, University of Leeds, Leeds, UK, 1990).
  2. M. J. Offside, M. G. Somekh, “A phase-sensitive optical heterodyne interferometer for surface height measurement,” Trans. Inst. Meas. Control (London) 13, 115–123 (1991).
    [CrossRef]
  3. C. W. See, R. K. Appel, M. G. Somekh, “Scanning differential optical profilometer for simultaneous measurement of amplitude and phase variation,” Appl. Phys. Lett. 53, 10–12 (1988).
    [CrossRef]
  4. G. Makosch, B. Drollinger, “Surface profile measurement with a scanning differential ac interferometer,” Appl. Opt. 23, 930–933 (1984).
    [CrossRef]
  5. G. E. Sommargren, “Optical heterodyne profilometry,” Appl. Opt. 20, 610–618 (1981).
    [CrossRef] [PubMed]
  6. M. J. Downs, W. H. McGivern, H. J. Ferguson, “Optical system for measuring the profiles of super smooth surfaces,” Precis. Eng. 7, 211–215 (1985).
    [CrossRef]
  7. C. C. Huang, “Optical heterodyne profilometer,” Opt. Eng. 23, 365–370 (1984).
    [CrossRef]
  8. S. A. Barman, “Measurement of profiled surfaces using polarising optical interferometry,” Ph.D. dissertation (King’s College London, London, 1996).
  9. J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, New York, 1988), Eqs. (5)–(30).

1991 (1)

M. J. Offside, M. G. Somekh, “A phase-sensitive optical heterodyne interferometer for surface height measurement,” Trans. Inst. Meas. Control (London) 13, 115–123 (1991).
[CrossRef]

1988 (1)

C. W. See, R. K. Appel, M. G. Somekh, “Scanning differential optical profilometer for simultaneous measurement of amplitude and phase variation,” Appl. Phys. Lett. 53, 10–12 (1988).
[CrossRef]

1985 (1)

M. J. Downs, W. H. McGivern, H. J. Ferguson, “Optical system for measuring the profiles of super smooth surfaces,” Precis. Eng. 7, 211–215 (1985).
[CrossRef]

1984 (2)

C. C. Huang, “Optical heterodyne profilometer,” Opt. Eng. 23, 365–370 (1984).
[CrossRef]

G. Makosch, B. Drollinger, “Surface profile measurement with a scanning differential ac interferometer,” Appl. Opt. 23, 930–933 (1984).
[CrossRef]

1981 (1)

Appel, R. K.

C. W. See, R. K. Appel, M. G. Somekh, “Scanning differential optical profilometer for simultaneous measurement of amplitude and phase variation,” Appl. Phys. Lett. 53, 10–12 (1988).
[CrossRef]

Barman, S. A.

S. A. Barman, “Measurement of profiled surfaces using polarising optical interferometry,” Ph.D. dissertation (King’s College London, London, 1996).

Downs, M. J.

M. J. Downs, W. H. McGivern, H. J. Ferguson, “Optical system for measuring the profiles of super smooth surfaces,” Precis. Eng. 7, 211–215 (1985).
[CrossRef]

Drollinger, B.

G. Makosch, B. Drollinger, “Surface profile measurement with a scanning differential ac interferometer,” Appl. Opt. 23, 930–933 (1984).
[CrossRef]

Ferguson, H. J.

M. J. Downs, W. H. McGivern, H. J. Ferguson, “Optical system for measuring the profiles of super smooth surfaces,” Precis. Eng. 7, 211–215 (1985).
[CrossRef]

Goodman, J. W.

J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, New York, 1988), Eqs. (5)–(30).

Huang, C. C.

C. C. Huang, “Optical heterodyne profilometer,” Opt. Eng. 23, 365–370 (1984).
[CrossRef]

Makosch, G.

G. Makosch, B. Drollinger, “Surface profile measurement with a scanning differential ac interferometer,” Appl. Opt. 23, 930–933 (1984).
[CrossRef]

Mason, N. M.

N. M. Mason, “Critical dimension measurement of semiconductor features,” Ph.D. dissertation (Department of Electronic and Electrical Engineering, University of Leeds, Leeds, UK, 1990).

McGivern, W. H.

M. J. Downs, W. H. McGivern, H. J. Ferguson, “Optical system for measuring the profiles of super smooth surfaces,” Precis. Eng. 7, 211–215 (1985).
[CrossRef]

Offside, M. J.

M. J. Offside, M. G. Somekh, “A phase-sensitive optical heterodyne interferometer for surface height measurement,” Trans. Inst. Meas. Control (London) 13, 115–123 (1991).
[CrossRef]

See, C. W.

C. W. See, R. K. Appel, M. G. Somekh, “Scanning differential optical profilometer for simultaneous measurement of amplitude and phase variation,” Appl. Phys. Lett. 53, 10–12 (1988).
[CrossRef]

Somekh, M. G.

M. J. Offside, M. G. Somekh, “A phase-sensitive optical heterodyne interferometer for surface height measurement,” Trans. Inst. Meas. Control (London) 13, 115–123 (1991).
[CrossRef]

C. W. See, R. K. Appel, M. G. Somekh, “Scanning differential optical profilometer for simultaneous measurement of amplitude and phase variation,” Appl. Phys. Lett. 53, 10–12 (1988).
[CrossRef]

Sommargren, G. E.

Appl. Opt. (2)

G. Makosch, B. Drollinger, “Surface profile measurement with a scanning differential ac interferometer,” Appl. Opt. 23, 930–933 (1984).
[CrossRef]

G. E. Sommargren, “Optical heterodyne profilometry,” Appl. Opt. 20, 610–618 (1981).
[CrossRef] [PubMed]

Appl. Phys. Lett. (1)

C. W. See, R. K. Appel, M. G. Somekh, “Scanning differential optical profilometer for simultaneous measurement of amplitude and phase variation,” Appl. Phys. Lett. 53, 10–12 (1988).
[CrossRef]

Opt. Eng. (1)

C. C. Huang, “Optical heterodyne profilometer,” Opt. Eng. 23, 365–370 (1984).
[CrossRef]

Precis. Eng. (1)

M. J. Downs, W. H. McGivern, H. J. Ferguson, “Optical system for measuring the profiles of super smooth surfaces,” Precis. Eng. 7, 211–215 (1985).
[CrossRef]

Trans. Inst. Meas. Control (London) (1)

M. J. Offside, M. G. Somekh, “A phase-sensitive optical heterodyne interferometer for surface height measurement,” Trans. Inst. Meas. Control (London) 13, 115–123 (1991).
[CrossRef]

Other (3)

N. M. Mason, “Critical dimension measurement of semiconductor features,” Ph.D. dissertation (Department of Electronic and Electrical Engineering, University of Leeds, Leeds, UK, 1990).

S. A. Barman, “Measurement of profiled surfaces using polarising optical interferometry,” Ph.D. dissertation (King’s College London, London, 1996).

J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, New York, 1988), Eqs. (5)–(30).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (12)

Fig. 1
Fig. 1

Schematic diagram of the optical arrangement of the double-focus polarization interference microscope.

Fig. 2
Fig. 2

Expanded view of the objective lens and sample positions in the double-focus microscope.

Fig. 3
Fig. 3

Signal value as a function of focal position for a feature of height equal to 30 nm.

Fig. 4
Fig. 4

Comparison of a computationally generated plot (top) and an experimental response (bottom) to a 36-nm-high step when the sample is placed at the null position. The shape and position of the sample are shown by the dotted–dashed line in the top computational plot.

Fig. 5
Fig. 5

Focus sensitivity of a step of height 0.1 µm, with the sample placed at the null position.

Fig. 6
Fig. 6

Comparison of a computationally generated plot (top) and a experimental response (bottom) of a 36-nm-high step when the sample is placed at top focus position. The shape and position of the sample are shown by the dotted–dashed line in the top computational plot.

Fig. 7
Fig. 7

Basic principle of the double-aperture microscope. The diagram shows two differently polarized beams of different areas focused by an objective lens to the same focal plane. At the focal plane the phases of both beams are flat, and the beam spots have different sizes.

Fig. 8
Fig. 8

Computationally generated plot to show the double-aperture microscope response to a step of height 0.1 µm.

Fig. 9
Fig. 9

Computationally generated plot to show the double-aperture microscope response to a step of height 1 µm.

Fig. 10
Fig. 10

Signal strength variation with focal position.

Fig. 11
Fig. 11

Basic principle of operation of the rotational prism solution. The spots falling on the sample surface are elongated in orthogonal directions.

Fig. 12
Fig. 12

Arrangement of the rotational prism solution. Rectangular boxes 1 and 2 represent the polarizations that are separated by combinations of the two beam splitters. The orientation of each slit of light is shown by the orientation of each rectangle. The arrow within each rectangular box defines the direction of travel of the light.

Metrics