Abstract

A photoemission electron microscope based on a new contrast mechanism “interference contrast” is applied to characterize extreme ultraviolet lithography mask blank defects. Inspection results show that positioning of interference destructive condition (node of standing wave field) on surface of multilayer in the local region of a phase defect is necessary to obtain best visibility of the defect on mask blank. A comparative experiment reveals superiority of the interference contrast photoemission electron microscope (Extreme UV illumination) over a topographic contrast one (UV illumination with Hg discharge lamp) in detecting extreme ultraviolet mask blank phase defects. A depth-resolved detection of a mask blank defect, either by measuring anti-node peak shift in the EUV-PEEM image under varying inspection wavelength condition or by counting interference fringes with a fixed illumination wavelength, is discussed.

© 2008 Optical Society of America

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  1. K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).
  2. T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
    [CrossRef]
  3. Y. Tezuka, M. Ito,T. Terasawa, and T. Tomie, "Actinic detection and signal characterization of multilayer defect on EUV mask blanks," Proc. SPIE 5567, 791-799 (2004).
    [CrossRef]
  4. K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).
  5. J. Lin, U. Neuhauesler, J. Slieh, and U. Kleinberg "Actinic extreme ultraviolet lithogrphy mask blank defect inspection by photoemission microscopy," J. Vac. Sci. Technol. B 24, 2631-2635 (2006).
  6. V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
    [CrossRef]
  7. A. Oelsner, O. Schmidt, M. Schicketanz, and G. Schönhense "Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy," Rev. Sci. Instrum. 72, 3968-3974 (2001).
    [CrossRef]
  8. K. Siegrist, E. Williams, and V. Ballarotto, "Characterizing topography-induced contrast in photoelectron emission microscopy," J. Vac. Sci. Technol. A 21, 1098-1102 (2003).
  9. G. Schönhense, A. Oelsner, and O. Schmidt, "Time-of-flight photoemission electron microscopy-a new way to chemical surface analysis," Surf. Sci. 480, 180-187 (2001).
    [CrossRef]
  10. C. M. Schneider and G. Schönhense, "Investigating surface magnetism by means of photoexcitation electron emission microscopy," Rep. Prog. Phys. 65, 1785-1839 (2002).
    [CrossRef]
  11. G. Schönhense, U. Kleineberg, German patent DE 100 32 979 A1 (Jan.17, 2002).
  12. J. Lin, N. Weber, J. Maul, S. Hendel, K. Rott, M. Merkel, G. Schönhense, and U. Kleingerg, "At-wavelength inspection of sub-40nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy," Opt. Lett. 32, 1875-1877 (2007).
    [CrossRef] [PubMed]
  13. D. L. Windt, "IMD-Software for modeling the optical properties of multilayer films," Comput. Phys. 12360-372 (1998).
    [CrossRef]
  14. D. T. Attwood, Soft X-ray and Extreme Ultraviolet Radiation: Principle and Application (Cambridge University Press, 2000).

2007 (1)

2006 (2)

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

J. Lin, U. Neuhauesler, J. Slieh, and U. Kleinberg "Actinic extreme ultraviolet lithogrphy mask blank defect inspection by photoemission microscopy," J. Vac. Sci. Technol. B 24, 2631-2635 (2006).

2005 (2)

V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
[CrossRef]

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

2004 (2)

Y. Tezuka, M. Ito,T. Terasawa, and T. Tomie, "Actinic detection and signal characterization of multilayer defect on EUV mask blanks," Proc. SPIE 5567, 791-799 (2004).
[CrossRef]

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

2003 (1)

K. Siegrist, E. Williams, and V. Ballarotto, "Characterizing topography-induced contrast in photoelectron emission microscopy," J. Vac. Sci. Technol. A 21, 1098-1102 (2003).

2002 (1)

C. M. Schneider and G. Schönhense, "Investigating surface magnetism by means of photoexcitation electron emission microscopy," Rep. Prog. Phys. 65, 1785-1839 (2002).
[CrossRef]

2001 (2)

G. Schönhense, A. Oelsner, and O. Schmidt, "Time-of-flight photoemission electron microscopy-a new way to chemical surface analysis," Surf. Sci. 480, 180-187 (2001).
[CrossRef]

A. Oelsner, O. Schmidt, M. Schicketanz, and G. Schönhense "Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy," Rev. Sci. Instrum. 72, 3968-3974 (2001).
[CrossRef]

1998 (1)

D. L. Windt, "IMD-Software for modeling the optical properties of multilayer films," Comput. Phys. 12360-372 (1998).
[CrossRef]

Ballarotto, V.

K. Siegrist, E. Williams, and V. Ballarotto, "Characterizing topography-induced contrast in photoelectron emission microscopy," J. Vac. Sci. Technol. A 21, 1098-1102 (2003).

Barty, A.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Endo, M.

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

Farys, V.

V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
[CrossRef]

Goldberg, K. A.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Haga, T.

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

Han, H.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Hanamoto, K.

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

Hendel, S.

Idir, M.

V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
[CrossRef]

Ito, M.

Y. Tezuka, M. Ito,T. Terasawa, and T. Tomie, "Actinic detection and signal characterization of multilayer defect on EUV mask blanks," Proc. SPIE 5567, 791-799 (2004).
[CrossRef]

Kearney, P.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Kinoshita, K.

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

Kleinberg, U.

J. Lin, U. Neuhauesler, J. Slieh, and U. Kleinberg "Actinic extreme ultraviolet lithogrphy mask blank defect inspection by photoemission microscopy," J. Vac. Sci. Technol. B 24, 2631-2635 (2006).

Kleingerg, U.

Liang, T.

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

Lin, J.

J. Lin, N. Weber, J. Maul, S. Hendel, K. Rott, M. Merkel, G. Schönhense, and U. Kleingerg, "At-wavelength inspection of sub-40nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy," Opt. Lett. 32, 1875-1877 (2007).
[CrossRef] [PubMed]

J. Lin, U. Neuhauesler, J. Slieh, and U. Kleinberg "Actinic extreme ultraviolet lithogrphy mask blank defect inspection by photoemission microscopy," J. Vac. Sci. Technol. B 24, 2631-2635 (2006).

Liu, Y.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Maul, J.

Merkel, M.

Muffato, V.

V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
[CrossRef]

Nagpal, R.

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

Neuhauesler, U.

J. Lin, U. Neuhauesler, J. Slieh, and U. Kleinberg "Actinic extreme ultraviolet lithogrphy mask blank defect inspection by photoemission microscopy," J. Vac. Sci. Technol. B 24, 2631-2635 (2006).

Oelsner, A.

G. Schönhense, A. Oelsner, and O. Schmidt, "Time-of-flight photoemission electron microscopy-a new way to chemical surface analysis," Surf. Sci. 480, 180-187 (2001).
[CrossRef]

A. Oelsner, O. Schmidt, M. Schicketanz, and G. Schönhense "Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy," Rev. Sci. Instrum. 72, 3968-3974 (2001).
[CrossRef]

Polack, P.

V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
[CrossRef]

Rott, K.

Sandez, P.

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

Schiavone, P.

V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
[CrossRef]

Schicketanz, M.

A. Oelsner, O. Schmidt, M. Schicketanz, and G. Schönhense "Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy," Rev. Sci. Instrum. 72, 3968-3974 (2001).
[CrossRef]

Schmidt, O.

A. Oelsner, O. Schmidt, M. Schicketanz, and G. Schönhense "Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy," Rev. Sci. Instrum. 72, 3968-3974 (2001).
[CrossRef]

G. Schönhense, A. Oelsner, and O. Schmidt, "Time-of-flight photoemission electron microscopy-a new way to chemical surface analysis," Surf. Sci. 480, 180-187 (2001).
[CrossRef]

Schneider, C. M.

C. M. Schneider and G. Schönhense, "Investigating surface magnetism by means of photoexcitation electron emission microscopy," Rep. Prog. Phys. 65, 1785-1839 (2002).
[CrossRef]

Schönhense, G.

J. Lin, N. Weber, J. Maul, S. Hendel, K. Rott, M. Merkel, G. Schönhense, and U. Kleingerg, "At-wavelength inspection of sub-40nm defects in extreme ultraviolet lithography mask blank by photoemission electron microscopy," Opt. Lett. 32, 1875-1877 (2007).
[CrossRef] [PubMed]

C. M. Schneider and G. Schönhense, "Investigating surface magnetism by means of photoexcitation electron emission microscopy," Rep. Prog. Phys. 65, 1785-1839 (2002).
[CrossRef]

A. Oelsner, O. Schmidt, M. Schicketanz, and G. Schönhense "Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy," Rev. Sci. Instrum. 72, 3968-3974 (2001).
[CrossRef]

G. Schönhense, A. Oelsner, and O. Schmidt, "Time-of-flight photoemission electron microscopy-a new way to chemical surface analysis," Surf. Sci. 480, 180-187 (2001).
[CrossRef]

Shohi, T.

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

Shu, E.

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

Siegrist, K.

K. Siegrist, E. Williams, and V. Ballarotto, "Characterizing topography-induced contrast in photoelectron emission microscopy," J. Vac. Sci. Technol. A 21, 1098-1102 (2003).

Slieh, J.

J. Lin, U. Neuhauesler, J. Slieh, and U. Kleinberg "Actinic extreme ultraviolet lithogrphy mask blank defect inspection by photoemission microscopy," J. Vac. Sci. Technol. B 24, 2631-2635 (2006).

Stivers, A.

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

Taylor, J.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Terasawa, T.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Y. Tezuka, M. Ito,T. Terasawa, and T. Tomie, "Actinic detection and signal characterization of multilayer defect on EUV mask blanks," Proc. SPIE 5567, 791-799 (2004).
[CrossRef]

Tezuka, Y.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Y. Tezuka, M. Ito,T. Terasawa, and T. Tomie, "Actinic detection and signal characterization of multilayer defect on EUV mask blanks," Proc. SPIE 5567, 791-799 (2004).
[CrossRef]

Tomie, T.

Y. Tezuka, M. Ito,T. Terasawa, and T. Tomie, "Actinic detection and signal characterization of multilayer defect on EUV mask blanks," Proc. SPIE 5567, 791-799 (2004).
[CrossRef]

Watanabe, T.

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

Weber, N.

Williams, E.

K. Siegrist, E. Williams, and V. Ballarotto, "Characterizing topography-induced contrast in photoelectron emission microscopy," J. Vac. Sci. Technol. A 21, 1098-1102 (2003).

Windt, D. L.

D. L. Windt, "IMD-Software for modeling the optical properties of multilayer films," Comput. Phys. 12360-372 (1998).
[CrossRef]

Wood, O.

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Zhang, G.

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

Appl. Phys. Lett. (1)

V. Farys, P. Schiavone, P. Polack, M. Idir, and V. Muffato, "Highly sensitive detection technology of buried defects in extreme ultraviolet masks using at-wavelength scanning dark-field microscopy," Appl. Phys. Lett. 87,024102 (2005).
[CrossRef]

Comput. Phys. (1)

D. L. Windt, "IMD-Software for modeling the optical properties of multilayer films," Comput. Phys. 12360-372 (1998).
[CrossRef]

J. Vac. Sci. Technol. A (1)

K. Siegrist, E. Williams, and V. Ballarotto, "Characterizing topography-induced contrast in photoelectron emission microscopy," J. Vac. Sci. Technol. A 21, 1098-1102 (2003).

J. Vac. Sci. Technol. B (2)

K. Kinoshita, T. Haga, K. Hanamoto,T. Shohi, M. Endo, and T. Watanabe, "Actinic mask metrology for extreme ultraviolet lithography," J. Vac. Sci. Technol. B 22, 264-267 (2004).

J. Lin, U. Neuhauesler, J. Slieh, and U. Kleinberg "Actinic extreme ultraviolet lithogrphy mask blank defect inspection by photoemission microscopy," J. Vac. Sci. Technol. B 24, 2631-2635 (2006).

J.Vac.Sci.Technol. B (1)

K. A. Goldberg, A. Barty, Y. Liu, P. Kearney, Y. Tezuka, T. Terasawa, J. Taylor, H. Han, and O. WoodII, "Actinic inspection of extreme ultraviolet programmed multilayer defects and cross-comparison measurements," J.Vac.Sci.Technol. B 24, 2824-2828 (2006).

Opt. Lett. (1)

Proc. SPIE (1)

T. Liang, P. Sandez, G. Zhang, E. Shu, R. Nagpal, and A. Stivers, " Understand and reduction of defect on finished EUV mask," Proc. SPIE 5752, 654-662 (2005).
[CrossRef]

Proc.SPIE (1)

Y. Tezuka, M. Ito,T. Terasawa, and T. Tomie, "Actinic detection and signal characterization of multilayer defect on EUV mask blanks," Proc. SPIE 5567, 791-799 (2004).
[CrossRef]

Rep. Prog. Phys. (1)

C. M. Schneider and G. Schönhense, "Investigating surface magnetism by means of photoexcitation electron emission microscopy," Rep. Prog. Phys. 65, 1785-1839 (2002).
[CrossRef]

Rev. Sci. Instrum. (1)

A. Oelsner, O. Schmidt, M. Schicketanz, and G. Schönhense "Microspectroscopy and imaging using a delay line detector in time-of-flight photoemission microscopy," Rev. Sci. Instrum. 72, 3968-3974 (2001).
[CrossRef]

Surf. Sci. (1)

G. Schönhense, A. Oelsner, and O. Schmidt, "Time-of-flight photoemission electron microscopy-a new way to chemical surface analysis," Surf. Sci. 480, 180-187 (2001).
[CrossRef]

Other (2)

G. Schönhense, U. Kleineberg, German patent DE 100 32 979 A1 (Jan.17, 2002).

D. T. Attwood, Soft X-ray and Extreme Ultraviolet Radiation: Principle and Application (Cambridge University Press, 2000).

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Figures (6)

Fig. 1.
Fig. 1.

Illustration of the modified EUV-PEEM. The enlarged diagram of the sample illustrates two types of defects (bump and pit) on top of a multilayer surface in the standing wave field. Z=0 is the position of the mask blank surface. The defect penetrates through node (N) and anti-node (AN) of the field alternatively.

Fig. 2.
Fig. 2.

Calculated electric field contour for a EUVL multilayer stack (z=0 is the position of multilayer surface. For eye guide, multilayer surface is marked by a light blue line in the Fig.2; z>0 ML stack) as a function of wavelength and depth into the multilayer stack at a EUV incident angle of 40 relative to the mask normal using IMD software[13]. The marked dashed red lines are used to indicate spatial shift of the anti-node peak (z coordinate) induced by a variation of illumination wavelength. A, B and C points correspond to the case of illumination wavelengths of 13.5, 13.4 and 13.3 nm, respectively.

Fig. 3.
Fig. 3.

Phase defects layout in the array with spacing of ~10 µm (left), or in pit-line pattern (middle) with varying proximity to the line (the dark dots around the line represent pit defects with varying distance to edge of the line as marked in the sketch). Image (right) is a cross sectional SEM photo of the absorbing line. I, II and III mark the defect-free multilayer, multilayer slope and absorbing zone, respectively. The grainy structure on top of multilayer is the deposited gold material for a purpose of obtaining SEM image of the multilayer structure. The dark dot in the middle of the image is void formed during the gold deposition.

Fig. 4.
Fig. 4.

EUV-PEEM image of pit-type defects in (a) the array pattern (FoV~70µm, backfield corrected) at inspection wavelength of 13.5nm and (b) pit-line pattern (FoV~12µm) at 13.5 nm to 13.1nm. To guide the eye, a white and a black arrows are used to align one of the lines of the black and white dots array in Fig. 4(a) respectively, the pit defects closest to the line in (b) are marked with #1,2,3,4 and 5, and line-scan profiles of the defects are given in the inset. The defects have a distance of 300 (#1), 250, 200 150 100 (#5) nm from the edge of the line, respectively. The two markers in the image center have sizes of 300 (w)×10 (h) nm (left marker) and 500 (w)×10 (h) nm (right marker), respectively.

Fig. 5.
Fig. 5.

A typical line-scan profile across defect-free multilayer surface (marked as I), multilayer slope (II) as well as the absorbing line (III). The scanning position is indicated by the line with ending points as shown in Fig.4 (b).

Fig. 6.
Fig. 6.

“Tomographic” EUV-PEEM image obtained with an EUVL mask blank stack at 13.5 nm. The curve is a line-scan profile averaged over five different lines scanned perpendicularly across the fringes. The bright region above the image center is caused by an inhomogeneous EUV illumination. The diagram in the upper right of the figure illustrates one case of edge variation of a defect in the standing wave field (AN: anti-node, N: node). Another defect appears close to the right edge of the PEEM image.

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