Abstract

A nondestructive method for measuring the duty cycles of metal grating masks formed on top of dielectric substrates is proposed. For a near-normal angle of incidence, the zeroth diffracted order transmission efficiency curves for both TE and TM polarized probe lights, as a function of duty cycles, behave linearly in the duty cycle ranging from 0 to 1. By comparing the measured efficiencies, or the ratio of zeroth-order transmission efficiency for TM polarization to that for TE polarization, with that of the rigorous-coupled wave analysis (RCWA) method for a fixed grating period and depth, one can determine the duty cycle of the grating. By selecting the probe light appropriately, the measurement errors originating from deviations of the incident angle and grating depth can be negligible. This method is applicable for all metal gratings, which are not easy to measure nondestructively due to fine grooves smaller than the wavelength. This method is simple, accurate, nondestructive, and low-cost. The results of experimental verification are presented and show excellent agreement with scanning electron microscope images.

© 2011 Optical Society of America

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S. Gilbertson, H. Mashiko, C. Li, E. Moon, and Z. Chang, “Effect of laser pulse duration on extreme ultraviolet spectra from double optical grating,” Appl. Phys. Lett. 93, 111105(2008).
[CrossRef]

2005

2004

H.-T. Huang and F. L. Terry Jr., “Spectroscopic elllipsometry and reflectometry from gratings (scatterometry) for critical dimension measurement and in situ, real-time process monitoring,” Thin Solid Films 455–456, 828–836 (2004).
[CrossRef]

2003

2002

E. M. Drege, J. A. Reed, and D. M. Byrne, “Linearized inversion of scatterometric data to obtain surface profile information,” Opt. Eng. 41, 225–236 (2002).
[CrossRef]

1999

1997

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

1996

1995

1994

M. D. Perry and G. Mourou, “Terawatt to petawatt subpicosecond lasers,” Science 264, 917–924 (1994).
[CrossRef] [PubMed]

1985

D. Strickland and G. Mourou, “Compression of amplified chirped optical pulses,” Opt. Commun. 56, 219–221 (1985).
[CrossRef]

Bischoff, J.

Bodefeld, R.

Byrne, D. M.

E. M. Drege, J. A. Reed, and D. M. Byrne, “Linearized inversion of scatterometric data to obtain surface profile information,” Opt. Eng. 41, 225–236 (2002).
[CrossRef]

Cao, H.

Chang, Z.

E. Moon, H. Wang, S. Gilbertson, H. Mashiko, M. Chini, and Z. Chang, “Advances in carrier-envelope phase stabilization of grating-based chirped-pulse amplifiers,” Laser Photon. Rev. 4, 160–177 (2010).
[CrossRef]

S. Gilbertson, H. Mashiko, C. Li, E. Moon, and Z. Chang, “Effect of laser pulse duration on extreme ultraviolet spectra from double optical grating,” Appl. Phys. Lett. 93, 111105(2008).
[CrossRef]

Chini, M.

E. Moon, H. Wang, S. Gilbertson, H. Mashiko, M. Chini, and Z. Chang, “Advances in carrier-envelope phase stabilization of grating-based chirped-pulse amplifiers,” Laser Photon. Rev. 4, 160–177 (2010).
[CrossRef]

Drege, E. M.

E. M. Drege, J. A. Reed, and D. M. Byrne, “Linearized inversion of scatterometric data to obtain surface profile information,” Opt. Eng. 41, 225–236 (2002).
[CrossRef]

Evans, M. S.

Fan, Z.

Farmiga, N. O.

Feng, J.

Gaylord, T. K.

Gilbertson, S.

E. Moon, H. Wang, S. Gilbertson, H. Mashiko, M. Chini, and Z. Chang, “Advances in carrier-envelope phase stabilization of grating-based chirped-pulse amplifiers,” Laser Photon. Rev. 4, 160–177 (2010).
[CrossRef]

S. Gilbertson, H. Mashiko, C. Li, E. Moon, and Z. Chang, “Effect of laser pulse duration on extreme ultraviolet spectra from double optical grating,” Appl. Phys. Lett. 93, 111105(2008).
[CrossRef]

Grann, E. B.

Hehl, K.

Heyer, H.

Hirsh, J.

Hirsh, J. I.

Hosch, J. W.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

Huang, H.-T.

H.-T. Huang and F. L. Terry Jr., “Spectroscopic elllipsometry and reflectometry from gratings (scatterometry) for critical dimension measurement and in situ, real-time process monitoring,” Thin Solid Films 455–456, 828–836 (2004).
[CrossRef]

Jin, Y.

Lalanne, P.

Li, C.

S. Gilbertson, H. Mashiko, C. Li, E. Moon, and Z. Chang, “Effect of laser pulse duration on extreme ultraviolet spectra from double optical grating,” Appl. Phys. Lett. 93, 111105(2008).
[CrossRef]

Li, L.

Lu, P.

Ma, J.

Marciante, J. R.

Mashiko, H.

E. Moon, H. Wang, S. Gilbertson, H. Mashiko, M. Chini, and Z. Chang, “Advances in carrier-envelope phase stabilization of grating-based chirped-pulse amplifiers,” Laser Photon. Rev. 4, 160–177 (2010).
[CrossRef]

S. Gilbertson, H. Mashiko, C. Li, E. Moon, and Z. Chang, “Effect of laser pulse duration on extreme ultraviolet spectra from double optical grating,” Appl. Phys. Lett. 93, 111105(2008).
[CrossRef]

McNeil, J. R.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, and J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vac. Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

Moharam, M. G.

Mohaupt, U.

Moon, E.

E. Moon, H. Wang, S. Gilbertson, H. Mashiko, M. Chini, and Z. Chang, “Advances in carrier-envelope phase stabilization of grating-based chirped-pulse amplifiers,” Laser Photon. Rev. 4, 160–177 (2010).
[CrossRef]

S. Gilbertson, H. Mashiko, C. Li, E. Moon, and Z. Chang, “Effect of laser pulse duration on extreme ultraviolet spectra from double optical grating,” Appl. Phys. Lett. 93, 111105(2008).
[CrossRef]

Morris, G. M.

Mourou, G.

M. D. Perry and G. Mourou, “Terawatt to petawatt subpicosecond lasers,” Science 264, 917–924 (1994).
[CrossRef] [PubMed]

D. Strickland and G. Mourou, “Compression of amplified chirped optical pulses,” Opt. Commun. 56, 219–221 (1985).
[CrossRef]

Murnane, M. R.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, and J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vac. Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

Naqvi, S. S. H.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, and J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vac. Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

Palme, M.

Perry, M. D.

M. D. Perry and G. Mourou, “Terawatt to petawatt subpicosecond lasers,” Science 264, 917–924 (1994).
[CrossRef] [PubMed]

Pommet, D. A.

Prins, S. L.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

Raymond, C. J.

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, and J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vac. Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

Reed, J. A.

E. M. Drege, J. A. Reed, and D. M. Byrne, “Linearized inversion of scatterometric data to obtain surface profile information,” Opt. Eng. 41, 225–236 (2002).
[CrossRef]

Ru, H.

Sauerbrey, R.

Schnabel, B.

Shao, J.

Strickland, D.

D. Strickland and G. Mourou, “Compression of amplified chirped optical pulses,” Opt. Commun. 56, 219–221 (1985).
[CrossRef]

Ta, H. T.

Terry, F. L.

H.-T. Huang and F. L. Terry Jr., “Spectroscopic elllipsometry and reflectometry from gratings (scatterometry) for critical dimension measurement and in situ, real-time process monitoring,” Thin Solid Films 455–456, 828–836 (2004).
[CrossRef]

Theobald, W. G.

Wang, H.

E. Moon, H. Wang, S. Gilbertson, H. Mashiko, M. Chini, and Z. Chang, “Advances in carrier-envelope phase stabilization of grating-based chirped-pulse amplifiers,” Laser Photon. Rev. 4, 160–177 (2010).
[CrossRef]

Wang, J.

Wang, S.

Wei, H.

Welsch, E.

Wenke, L.

Zeng, L.

Zhang, Y.

Zhou, C.

Appl. Opt.

Appl. Phys. Lett.

S. Gilbertson, H. Mashiko, C. Li, E. Moon, and Z. Chang, “Effect of laser pulse duration on extreme ultraviolet spectra from double optical grating,” Appl. Phys. Lett. 93, 111105(2008).
[CrossRef]

J. Opt. Soc. Am. A

J. Vac. Sci. Technol. B

C. J. Raymond, M. R. Murnane, S. S. H. Naqvi, and J. R. McNeil, “Metrology of subwavelength photoresist gratings using optical scatterometry,” J. Vac. Sci. Technol. B 13, 1484–1495 (1995).
[CrossRef]

C. J. Raymond, M. R. Murnane, S. L. Prins, S. S. H. Naqvi, J. R. McNeil, and J. W. Hosch, “Multiparameter grating metrology using optical scatterometry,” J. Vac. Sci. Technol. B 15, 361–368 (1997).
[CrossRef]

Laser Photon. Rev.

E. Moon, H. Wang, S. Gilbertson, H. Mashiko, M. Chini, and Z. Chang, “Advances in carrier-envelope phase stabilization of grating-based chirped-pulse amplifiers,” Laser Photon. Rev. 4, 160–177 (2010).
[CrossRef]

Opt. Commun.

D. Strickland and G. Mourou, “Compression of amplified chirped optical pulses,” Opt. Commun. 56, 219–221 (1985).
[CrossRef]

Opt. Eng.

E. M. Drege, J. A. Reed, and D. M. Byrne, “Linearized inversion of scatterometric data to obtain surface profile information,” Opt. Eng. 41, 225–236 (2002).
[CrossRef]

Opt. Lett.

Science

M. D. Perry and G. Mourou, “Terawatt to petawatt subpicosecond lasers,” Science 264, 917–924 (1994).
[CrossRef] [PubMed]

Thin Solid Films

H.-T. Huang and F. L. Terry Jr., “Spectroscopic elllipsometry and reflectometry from gratings (scatterometry) for critical dimension measurement and in situ, real-time process monitoring,” Thin Solid Films 455–456, 828–836 (2004).
[CrossRef]

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Figures (9)

Fig. 1
Fig. 1

Schematic illustration of a binary metal grating mask made on fused-silica ( n 1 , n 2 , and n r , refractive indices of air, substrate, and grating ridge, respectively; Λ, grating period; b, ridge width; h, groove depth).

Fig. 2
Fig. 2

Schematic diagram of the experimental setup for measuring the zeroth-order transmitted efficiency.

Fig. 3
Fig. 3

Zeroth-order transmission efficiencies as a function of duty cycles for Cr grating patterned on fused-silica substrate with period Λ = 100 nm , 500 nm , and 1000 nm , respectively. The grating depth is assumed to be h = 100 nm . The probe light is linearly polarized with a wavelength of 632.8 nm and is normally incident on the grating. The refractive indices are n 1 = 1.0 , n 2 = 1.457 , n r = 3.12 i * 3.3 .

Fig. 4
Fig. 4

Zeroth-order transmission efficiencies as a function of duty cycles for Cr grating patterned on fused-silica substrate with different periods. (a)  Λ = 100 nm , (b)  Λ = 1000 nm . The other parameters used are the same as in Fig. 3.

Fig. 5
Fig. 5

Zeroth-order transmission efficiencies versus duty cycles for Cr gratings with different periods and incident angles. (a)  Λ = 100 nm , (b)  Λ = 1000 nm . The other parameters used in calculation are the same as in Fig. 3.

Fig. 6
Fig. 6

Zeroth-order transmission efficiencies versus duty cycles for Cr gratings with different period and probe-light wavelengths. (a)  Λ = 100 nm , (b)  Λ = 1000 nm . The refractive indices for Cr under incident wavelengths λ = 441 nm , 589 nm , and 6328 nm are n r = 2.27 i * 3.1 , 3.21 i * 3.3 , and 3.12 i * 3.3 , respectively.

Fig. 7
Fig. 7

TM 0 / TE 0 ratio versus duty cycles for Cr gratings on fused-silica substrates with different periods. The parameters used in calculation are the same as in Fig. 3.

Fig. 8
Fig. 8

Scanning electron micrograph image of the manufactured grating for (a) grating period Λ = 750 nm and (b) grating period Λ = 1980 nm . Note that the inset in (b) shows the backscattered electron image of the grating to facilitate measurement of the grating width.

Fig. 9
Fig. 9

Zeroth-order transmission efficiencies as a function of duty cycles for Cr gratings fabricated on fused-silica substrate with periods Λ = 750 nm and 1980 nm . The grating depth is 145 nm ; the probe light is TM polarized with a wavelength of 800 nm and is normally incident on the grating. The refractive indices are n 1 = 1.0 , n 2 = 1.45 , n r = 3.158 i * 3.46 .

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