Abstract

A method of imaging sub-0.5-μm-dense photoresist lines with the real-time scanning optical microscope by the use of elliptically polarized light is developed. The imaging method takes advantage of the fact that polarized light undergoes a change in polarization when reflected from a grating structure. A confocal scanning optical microscope is modified to image this light. The resulting images show an increase in the detected intensity of the light reflected from the substrate region of the grating. Increasing this signal level improves the ability of the microscope to make linewidth measurements on photoresist structures as small as 0.3 μm. Results from several different semiconductor substrates are presented. A brief review of the grating theory is presented to suggest possible origins for the increase in light intensity.

© 1994 Optical Society of America

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References

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    [Crossref]
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    [Crossref]
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    [Crossref]
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1993 (1)

1992 (3)

1990 (3)

1988 (2)

1985 (1)

T. K. Gaylord, M. G. Moharam, “Analysis and applications of optical diffraction by gratings,” Proc. IEEE 73, 894–937 (1985).
[Crossref]

1983 (2)

M. G. Moharam, T. K. Gaylord, “Three dimensional vector coupled-wave analysis of planar-grating diffraction,” J. Opt. Soc. Am. 73, 1105–1112 (1983).
[Crossref]

N. Garcia, “Exact calculations of p-polarized electromagnetic fields incident on grating surfaces: surface polariton resonances,” Opt. Commun. 45, 307–310 (1983).
[Crossref]

1982 (2)

M. G. Moharam, T. K. Gaylord, “Diffraction analysis of dielectric surface-relief gratings,” J. Opt. Soc. Am. 72, 1385–1392 (1982).
[Crossref]

D. L. Miller, M. Weber, “Enhanced electric field near gratings: comments on enhanced Raman scattering from surfaces,” Phys. Rev. B 26, 1075–1081 (1982).
[Crossref]

Aguilar, J. F.

J. F. Aguilar, E. R. Mendez, “Image of dielectric film structures on reflecting substrates” Integrated Circuit Metrology, Inspection, and Process Control VII, M. T. Postek, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1926, 18–26 (1993).

Betzig, E.

Chou, C.-H.

N. S. Levine, T. R. Corle, R. T. Mumaw, C.-H. Chou, G. S. Kino, “Multilevel CD/overlay metrology using a real-time confocal scanning optical microscope,” Microelectron. Eng. 11, 669–674 (1990).
[Crossref]

Corle, T. R.

T. R. Corle, “Submicron metrology in the semiconductor industry,” Solid-State Electron. 35, 391–402 (1992).
[Crossref]

N. S. Levine, T. R. Corle, R. T. Mumaw, C.-H. Chou, G. S. Kino, “Multilevel CD/overlay metrology using a real-time confocal scanning optical microscope,” Microelectron. Eng. 11, 669–674 (1990).
[Crossref]

G. Q. Xiao, T. R. Corle, G. S. Kino, “Real-time confocal scanning optical microscope,” Appl. Phys. Lett. 53, 716–718 (1988).
[Crossref]

Davidson, M. P.

M. P. Davidson, K. M. Monahan, R. J. Monteverde, “Linearity of coherence probe metrology: simulation and experiment,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 155–176 (1991).

Frank, J. R.

G. L. Wojcik, J. M. Mould, R. J. Monteverde, J. J. Prochazka, J. R. Frank, “Numerical simulation of thick linewidth measurements by reflected light,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 187–203 (1991).

Gallagher, N. C.

Garcia, N.

N. Garcia, “Exact calculations of p-polarized electromagnetic fields incident on grating surfaces: surface polariton resonances,” Opt. Commun. 45, 307–310 (1983).
[Crossref]

Gaylord, T. K.

Gupta, M. C.

Harris, T. D.

Kino, G. S.

N. S. Levine, T. R. Corle, R. T. Mumaw, C.-H. Chou, G. S. Kino, “Multilevel CD/overlay metrology using a real-time confocal scanning optical microscope,” Microelectron. Eng. 11, 669–674 (1990).
[Crossref]

G. Q. Xiao, T. R. Corle, G. S. Kino, “Real-time confocal scanning optical microscope,” Appl. Phys. Lett. 53, 716–718 (1988).
[Crossref]

Kok, Y. L.

Levine, N. S.

N. S. Levine, T. R. Corle, R. T. Mumaw, C.-H. Chou, G. S. Kino, “Multilevel CD/overlay metrology using a real-time confocal scanning optical microscope,” Microelectron. Eng. 11, 669–674 (1990).
[Crossref]

Mendez, E. R.

J. F. Aguilar, E. R. Mendez, “Image of dielectric film structures on reflecting substrates” Integrated Circuit Metrology, Inspection, and Process Control VII, M. T. Postek, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1926, 18–26 (1993).

Miller, D. L.

D. L. Miller, M. Weber, “Enhanced electric field near gratings: comments on enhanced Raman scattering from surfaces,” Phys. Rev. B 26, 1075–1081 (1982).
[Crossref]

Moharam, M. G.

Monahan, K. M.

M. P. Davidson, K. M. Monahan, R. J. Monteverde, “Linearity of coherence probe metrology: simulation and experiment,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 155–176 (1991).

Monteverde, R. J.

M. P. Davidson, K. M. Monahan, R. J. Monteverde, “Linearity of coherence probe metrology: simulation and experiment,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 155–176 (1991).

G. L. Wojcik, J. M. Mould, R. J. Monteverde, J. J. Prochazka, J. R. Frank, “Numerical simulation of thick linewidth measurements by reflected light,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 187–203 (1991).

Mould, J. M.

G. L. Wojcik, J. M. Mould, R. J. Monteverde, J. J. Prochazka, J. R. Frank, “Numerical simulation of thick linewidth measurements by reflected light,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 187–203 (1991).

Mumaw, R. T.

N. S. Levine, T. R. Corle, R. T. Mumaw, C.-H. Chou, G. S. Kino, “Multilevel CD/overlay metrology using a real-time confocal scanning optical microscope,” Microelectron. Eng. 11, 669–674 (1990).
[Crossref]

Naqvi, S. S. H.

Nguyen, D. T.

Peng, S. T.

Prochazka, J. J.

G. L. Wojcik, J. M. Mould, R. J. Monteverde, J. J. Prochazka, J. R. Frank, “Numerical simulation of thick linewidth measurements by reflected light,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 187–203 (1991).

Rustgi, M. L.

Trautman, J. K.

Weber, M.

D. L. Miller, M. Weber, “Enhanced electric field near gratings: comments on enhanced Raman scattering from surfaces,” Phys. Rev. B 26, 1075–1081 (1982).
[Crossref]

Weiner, J. S.

Whang, A. J. W.

Wijnaendts-van-Resandt, R. W.

R. W. Wijnaendts-van-Resandt, “Semiconductor metrology,” in Confocal MicroscopyT. Wilson, ed. (Academic, San Diego, Calif., 1990), pp. 339–360.

Wojcik, G. L.

G. L. Wojcik, J. M. Mould, R. J. Monteverde, J. J. Prochazka, J. R. Frank, “Numerical simulation of thick linewidth measurements by reflected light,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 187–203 (1991).

Wolfe, R.

Xiao, G. Q.

G. Q. Xiao, T. R. Corle, G. S. Kino, “Real-time confocal scanning optical microscope,” Appl. Phys. Lett. 53, 716–718 (1988).
[Crossref]

Appl. Opt. (2)

Appl. Phys. Lett. (1)

G. Q. Xiao, T. R. Corle, G. S. Kino, “Real-time confocal scanning optical microscope,” Appl. Phys. Lett. 53, 716–718 (1988).
[Crossref]

J. Opt. Soc. Am. (2)

J. Opt. Soc. Am. A (3)

J. Opt. Soc. Am. B (1)

Microelectron. Eng. (1)

N. S. Levine, T. R. Corle, R. T. Mumaw, C.-H. Chou, G. S. Kino, “Multilevel CD/overlay metrology using a real-time confocal scanning optical microscope,” Microelectron. Eng. 11, 669–674 (1990).
[Crossref]

Opt. Commun. (1)

N. Garcia, “Exact calculations of p-polarized electromagnetic fields incident on grating surfaces: surface polariton resonances,” Opt. Commun. 45, 307–310 (1983).
[Crossref]

Phys. Rev. B (1)

D. L. Miller, M. Weber, “Enhanced electric field near gratings: comments on enhanced Raman scattering from surfaces,” Phys. Rev. B 26, 1075–1081 (1982).
[Crossref]

Proc. IEEE (1)

T. K. Gaylord, M. G. Moharam, “Analysis and applications of optical diffraction by gratings,” Proc. IEEE 73, 894–937 (1985).
[Crossref]

Solid-State Electron. (1)

T. R. Corle, “Submicron metrology in the semiconductor industry,” Solid-State Electron. 35, 391–402 (1992).
[Crossref]

Other (4)

R. W. Wijnaendts-van-Resandt, “Semiconductor metrology,” in Confocal MicroscopyT. Wilson, ed. (Academic, San Diego, Calif., 1990), pp. 339–360.

M. P. Davidson, K. M. Monahan, R. J. Monteverde, “Linearity of coherence probe metrology: simulation and experiment,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 155–176 (1991).

G. L. Wojcik, J. M. Mould, R. J. Monteverde, J. J. Prochazka, J. R. Frank, “Numerical simulation of thick linewidth measurements by reflected light,” in Integrated Circuit Metrology, Inspection and Process Control V, W. H. Arnold, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1464, 187–203 (1991).

J. F. Aguilar, E. R. Mendez, “Image of dielectric film structures on reflecting substrates” Integrated Circuit Metrology, Inspection, and Process Control VII, M. T. Postek, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1926, 18–26 (1993).

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Figures (8)

Fig. 1
Fig. 1

Image of two five-line-dense array patterns of 0.45-μm-wide lines in 1.0-μm-thick photoresist on silicon.

Fig. 2
Fig. 2

Cross-sectional images and line scans through a dense array of lines in 1.0-μm-thick photoresist on silicon: (a) PE image and line scan of a 0.45-μm line–space array, (b) standard RSOM image and line scan of the same 0.45-μm structure, (c) PE image and line scan of a 0.35-μm line–space array, (d) standard RSOM image and line scan of the same 0.35-μm structure.

Fig. 3
Fig. 3

(a) Top = down image of a 0.4-μm-wide dense array of lines in 1.0-μm-thick photoresist on silicon near the center of a focus exposure array: (b) a site three exposure steps and three focus steps from the center, (c) a site three exposure steps and four focus steps from the center, (d) RSOM image of the structure in (a).

Fig. 4
Fig. 4

Schematic of the RSOM modified for PE imaging.

Fig. 5
Fig. 5

Illustration showing the relationship of the dense lines being imaged to the polarization axis for PE imaging.

Fig. 6
Fig. 6

Four top-down images of a 0.45-μm-dense array imaged at different focus positions and different rotational angles of the QWP: (a), (b) −17°; (c), (d) +17°.

Fig. 7
Fig. 7

Pie chart showing the effects of the QWP rotational angle for 0.45-μm-dense lines of photoresist on silicon.

Fig. 8
Fig. 8

Linewidth measurements made by PE imaging over a range of nominal linewidths from 0.40 to 1.0 μm on a focus exposure wafer in a 1.0-μm-thick deep UV photoresist on titanium on silicon dioxide on silicon: (a) correlation between electrical and optical measurements, (b) optical measurements of linewidth versus exposure.

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