Abstract

A microscopic method to inspect isolated sub 100 nm scale structures made of silicon is presented. This method is based upon an analysis of light intensity distributions at defocused images obtained along the optical axis normal to the sample plane. Experimental measurements of calibrated lines (height 50 nm, length 100 μm, and widths of 40–150 nm in 10 nm steps) on top of a monocrystalline silicon substrate are presented. Library of defocused images of calibrated lines is obtained experimentally and numerically with accordance to experimental setup parameters and measurements conditions. Processing of the measured defocused images and comparison with simulated ones from library allow one to distinguish between objects with a 10 nm change in width. It is shown that influence of optical system aberrations must be taken into account in order to achieve coincidence between simulation and measured results and increase accuracy of line width inspection accuracy. The limits of accuracy for object width measurements using this optical method are discussed.

© 2013 Optical Society of America

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  1. D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
    [CrossRef]
  2. C. J. Raymond, M. Littau, R. Markle, and M. Purdy, “Scatterometry for shallow trench isolation (STI) process metrology,” Proc. SPIE4344, 716–725 (2001).
    [CrossRef]
  3. R. J. Hoobler and E. Apak, “Optical critical dimension (OCD) measurements for profile monitoring and control: applications for mask inspection and fabrication,” Proc. SPIE5256, 638–645 (2003).
    [CrossRef]
  4. I. T. R. S. Roadmap, http://www.itrs.net/Links/2006Update/2006UpdateFinal.htm
  5. R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
    [CrossRef]
  6. R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
    [CrossRef]
  7. A. Arceo, B. Bunday, V. Vartanian, and R. Attota, “Patterned Defect & CD Metrology by TSOM Beyond the 22 nm Node,” Proc. SPIE8324, 83240E (2012).
    [CrossRef]
  8. R. Attota, T. A. Germer, and R. M. Silver, “Through-focus scanning-optical-microscope imaging method for nanoscale dimensional analysis,” Opt. Lett.33(17), 1990–1992 (2008).
    [CrossRef] [PubMed]
  9. A. V. Arecchi, T. Messadi, and R. J. Koshel, Field Guide to Illumination (SPIE Press, 2007)
  10. A. Taflove and S. C. Hagness, Computational Electrodynamics: The Finite-Difference Time-Domain Method, 3rd ed., Norwood, (Artech House, Inc., 2005)

2012 (1)

A. Arceo, B. Bunday, V. Vartanian, and R. Attota, “Patterned Defect & CD Metrology by TSOM Beyond the 22 nm Node,” Proc. SPIE8324, 83240E (2012).
[CrossRef]

2008 (1)

2003 (3)

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

R. J. Hoobler and E. Apak, “Optical critical dimension (OCD) measurements for profile monitoring and control: applications for mask inspection and fabrication,” Proc. SPIE5256, 638–645 (2003).
[CrossRef]

2002 (1)

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

2001 (1)

C. J. Raymond, M. Littau, R. Markle, and M. Purdy, “Scatterometry for shallow trench isolation (STI) process metrology,” Proc. SPIE4344, 716–725 (2001).
[CrossRef]

Apak, E.

R. J. Hoobler and E. Apak, “Optical critical dimension (OCD) measurements for profile monitoring and control: applications for mask inspection and fabrication,” Proc. SPIE5256, 638–645 (2003).
[CrossRef]

Arceo, A.

A. Arceo, B. Bunday, V. Vartanian, and R. Attota, “Patterned Defect & CD Metrology by TSOM Beyond the 22 nm Node,” Proc. SPIE8324, 83240E (2012).
[CrossRef]

Attota, R.

A. Arceo, B. Bunday, V. Vartanian, and R. Attota, “Patterned Defect & CD Metrology by TSOM Beyond the 22 nm Node,” Proc. SPIE8324, 83240E (2012).
[CrossRef]

R. Attota, T. A. Germer, and R. M. Silver, “Through-focus scanning-optical-microscope imaging method for nanoscale dimensional analysis,” Opt. Lett.33(17), 1990–1992 (2008).
[CrossRef] [PubMed]

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Bunday, B.

A. Arceo, B. Bunday, V. Vartanian, and R. Attota, “Patterned Defect & CD Metrology by TSOM Beyond the 22 nm Node,” Proc. SPIE8324, 83240E (2012).
[CrossRef]

Davidson, M.

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Davidson, M. P.

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

Elazami, A.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Fernand, C.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Germer, T. A.

Guevremont, M.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Henry, D.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Herisson, D.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Hoobler, R. J.

R. J. Hoobler and E. Apak, “Optical critical dimension (OCD) measurements for profile monitoring and control: applications for mask inspection and fabrication,” Proc. SPIE5256, 638–645 (2003).
[CrossRef]

Jun, J.

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Jun, J.-S. J.

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

Kremer, S.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Larrabee, R.

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Larrabee, R. D.

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

Littau, M.

C. J. Raymond, M. Littau, R. Markle, and M. Purdy, “Scatterometry for shallow trench isolation (STI) process metrology,” Proc. SPIE4344, 716–725 (2001).
[CrossRef]

Markle, R.

C. J. Raymond, M. Littau, R. Markle, and M. Purdy, “Scatterometry for shallow trench isolation (STI) process metrology,” Proc. SPIE4344, 716–725 (2001).
[CrossRef]

Marx, E.

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Neira, D.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Polli, M.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Purdy, M.

C. J. Raymond, M. Littau, R. Markle, and M. Purdy, “Scatterometry for shallow trench isolation (STI) process metrology,” Proc. SPIE4344, 716–725 (2001).
[CrossRef]

Raymond, C. J.

C. J. Raymond, M. Littau, R. Markle, and M. Purdy, “Scatterometry for shallow trench isolation (STI) process metrology,” Proc. SPIE4344, 716–725 (2001).
[CrossRef]

Russo, B.

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Silver, R. M.

R. Attota, T. A. Germer, and R. M. Silver, “Through-focus scanning-optical-microscope imaging method for nanoscale dimensional analysis,” Opt. Lett.33(17), 1990–1992 (2008).
[CrossRef] [PubMed]

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Stocker, M.

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

Stocker, M. T.

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

Thony, P.

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Vartanian, V.

A. Arceo, B. Bunday, V. Vartanian, and R. Attota, “Patterned Defect & CD Metrology by TSOM Beyond the 22 nm Node,” Proc. SPIE8324, 83240E (2012).
[CrossRef]

Opt. Lett. (1)

Proc. SPIE (5)

C. J. Raymond, M. Littau, R. Markle, and M. Purdy, “Scatterometry for shallow trench isolation (STI) process metrology,” Proc. SPIE4344, 716–725 (2001).
[CrossRef]

R. J. Hoobler and E. Apak, “Optical critical dimension (OCD) measurements for profile monitoring and control: applications for mask inspection and fabrication,” Proc. SPIE5256, 638–645 (2003).
[CrossRef]

R. M. Silver, R. Attota, M. Stocker, J. Jun, E. Marx, R. Larrabee, B. Russo, and M. Davidson, “Comparison of measured optical image profiles of silicon lines with two different theoretical models,” Proc. SPIE4689, 409–429 (2002).
[CrossRef]

R. Attota, R. M. Silver, M. T. Stocker, E. Marx, J.-S. J. Jun, M. P. Davidson, and R. D. Larrabee, “A new method to enhance overlay tool performance,” Proc. SPIE5038, 428–436 (2003).
[CrossRef]

A. Arceo, B. Bunday, V. Vartanian, and R. Attota, “Patterned Defect & CD Metrology by TSOM Beyond the 22 nm Node,” Proc. SPIE8324, 83240E (2012).
[CrossRef]

Proceedings of SPIE Vol. (1)

D. Herisson, D. Neira, C. Fernand, P. Thony, D. Henry, S. Kremer, M. Polli, M. Guevremont, and A. Elazami, “Spectroscopic ellipsometry for lithography front-end level CD control: a complete analysis for production integration,” Proceedings of SPIE Vol.5038, 264–273 (2003).
[CrossRef]

Other (3)

I. T. R. S. Roadmap, http://www.itrs.net/Links/2006Update/2006UpdateFinal.htm

A. V. Arecchi, T. Messadi, and R. J. Koshel, Field Guide to Illumination (SPIE Press, 2007)

A. Taflove and S. C. Hagness, Computational Electrodynamics: The Finite-Difference Time-Domain Method, 3rd ed., Norwood, (Artech House, Inc., 2005)

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Figures (4)

Fig. 1
Fig. 1

(a) Experimental setup, (b) SEM images of test objects.

Fig. 2
Fig. 2

Test objects measurements. (a) Normalized through-focus diffraction pattern obtained for the object with 40 nm CD. (b) Normalized through-focus diffraction pattern for the object with 50 nm CD. (c) Differential through-focus diffraction pattern for test objects with 40 and 50 nm CD.

Fig. 3
Fig. 3

Estimation of measurement accuracy. (a) Metric value curve measured for all test objects with use of 40 nm reference object; dashed lines denote ± 2σ standard deviation, blue for 40 nm CD value, red for 50 nm CD value (b) Metric value curve measured for all test objects with use of 90 nm reference object; dashed lines denote ± 2σ standard deviation, blue for 90 nm CD value, red for 100 nm CD value

Fig. 4
Fig. 4

Comparison between experimental and simulated normalized through-focus diffraction patterns. Left column corresponds to 150 nm CD value, middle column – 90 nm, right column – 40 nm. (a)-(c) Experimental results, (d)-(f) Simulation results with aberration correction. (g)-(i) Simulation results without aberration correction. (j)-(l) Difference between measured and simulated normalized through-focus diffraction patterns without aberration corrections. (m)-(o) Difference between measured and simulated normalized through-focus diffraction patterns with aberration correction.

Tables (2)

Tables Icon

Table 1 Recognition of object width with use of experimental library

Tables Icon

Table 2 Recognition of object width with use of simulated library

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