Abstract

Thin metal films show a residual transmission for light in the visible and UV spectral range. This transmission can be strongly reduced by an appropriate sub-wavelength patterning of the metal film. Our investigation is focused on metal films with a thickness much below 100nm, where the transmission response is dominated by the individual posts acting like antennas and cannot be attributed to the excitation of surface plasmons. The almost complete suppression of transmission for ultra-thin metal films depends mainly on the absorber width, but not on the pitch of the pattern. The effect is robust with respect to imperfections of the geometry or larger features imprinted into the sub-wavelength pattern.

© 2009 Optical Society of America

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References

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  1. T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
    [CrossRef]
  2. H. Raether, Surface Plasmons on Smooth and Rough Surfaces and on Gratings (Springer Verlag, Berlin, 1988).
  3. H. J. Lezec and T. Thio, "Diffracted evanescent wave model for enhanced and suppressed optical transmission through subwavelength hole arrays," Opt. Express 16,3629-3651 (2004).
    [CrossRef]
  4. Q. Cao and P. Lalanne, "Negative Role of Surface Plasmons in the Transmission of Metallic Gratings with Very Narrow Slits," Phys. Rev. Lett. 88,057403 (2002).
    [CrossRef] [PubMed]
  5. O. T. A. Janssen, H. P. Urbach, and G. W. ’t Hooft, "On the phase of plasmons excited by slits in a metal film," Opt. Express 14,11823-11832 (2006).
    [CrossRef] [PubMed]
  6. www.rit.edu/ 635dept5/thinfilms/thinfilms.htm
  7. K. D. Lucas, H. Tanabe, and A. Strojwas, "Efficient and rigorous three dimensional model for optical lithography simulation," J. Opt. Soc. Am. A 13,2187-2199 (1996).
    [CrossRef]
  8. L. Li, "Use of Fourier series in the analysis of discontinuous periodic structures," J. Opt. Soc. Am. A 13,1870-1876 (1996).
    [CrossRef]
  9. P. Evanschitzky and A. Erdmann, "Three dimensional EUV simulations: A new mask near field and imaging simulationsystem," Proc. SPIE 5992,1546 (2005).
  10. www.drlitho.com
  11. L. Novotny, "Effective wavelength scaling for optical antennas," Phys. Rev. Lett. 98,266802 (2007).
    [CrossRef] [PubMed]

2007

L. Novotny, "Effective wavelength scaling for optical antennas," Phys. Rev. Lett. 98,266802 (2007).
[CrossRef] [PubMed]

2006

2005

P. Evanschitzky and A. Erdmann, "Three dimensional EUV simulations: A new mask near field and imaging simulationsystem," Proc. SPIE 5992,1546 (2005).

2004

H. J. Lezec and T. Thio, "Diffracted evanescent wave model for enhanced and suppressed optical transmission through subwavelength hole arrays," Opt. Express 16,3629-3651 (2004).
[CrossRef]

2002

Q. Cao and P. Lalanne, "Negative Role of Surface Plasmons in the Transmission of Metallic Gratings with Very Narrow Slits," Phys. Rev. Lett. 88,057403 (2002).
[CrossRef] [PubMed]

1998

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
[CrossRef]

1996

’t Hooft, G. W.

Cao, Q.

Q. Cao and P. Lalanne, "Negative Role of Surface Plasmons in the Transmission of Metallic Gratings with Very Narrow Slits," Phys. Rev. Lett. 88,057403 (2002).
[CrossRef] [PubMed]

Ebbesen, T. W.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
[CrossRef]

Erdmann, A.

P. Evanschitzky and A. Erdmann, "Three dimensional EUV simulations: A new mask near field and imaging simulationsystem," Proc. SPIE 5992,1546 (2005).

Evanschitzky, P.

P. Evanschitzky and A. Erdmann, "Three dimensional EUV simulations: A new mask near field and imaging simulationsystem," Proc. SPIE 5992,1546 (2005).

Ghaemi, H. F.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
[CrossRef]

Janssen, O. T. A.

Lalanne, P.

Q. Cao and P. Lalanne, "Negative Role of Surface Plasmons in the Transmission of Metallic Gratings with Very Narrow Slits," Phys. Rev. Lett. 88,057403 (2002).
[CrossRef] [PubMed]

Lezec, H. J.

H. J. Lezec and T. Thio, "Diffracted evanescent wave model for enhanced and suppressed optical transmission through subwavelength hole arrays," Opt. Express 16,3629-3651 (2004).
[CrossRef]

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
[CrossRef]

Li, L.

Lucas, K. D.

Novotny, L.

L. Novotny, "Effective wavelength scaling for optical antennas," Phys. Rev. Lett. 98,266802 (2007).
[CrossRef] [PubMed]

Strojwas, A.

Tanabe, H.

Thio, T.

H. J. Lezec and T. Thio, "Diffracted evanescent wave model for enhanced and suppressed optical transmission through subwavelength hole arrays," Opt. Express 16,3629-3651 (2004).
[CrossRef]

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
[CrossRef]

Urbach, H. P.

Wolff, P. A.

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
[CrossRef]

J. Opt. Soc. Am. A

Nature (London)

T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, "Extraordinary optical transmission through sub-wavelength hole arrays," Nature (London) 391,667-689 (1998).
[CrossRef]

Opt. Express

H. J. Lezec and T. Thio, "Diffracted evanescent wave model for enhanced and suppressed optical transmission through subwavelength hole arrays," Opt. Express 16,3629-3651 (2004).
[CrossRef]

O. T. A. Janssen, H. P. Urbach, and G. W. ’t Hooft, "On the phase of plasmons excited by slits in a metal film," Opt. Express 14,11823-11832 (2006).
[CrossRef] [PubMed]

Phys. Rev. Lett.

Q. Cao and P. Lalanne, "Negative Role of Surface Plasmons in the Transmission of Metallic Gratings with Very Narrow Slits," Phys. Rev. Lett. 88,057403 (2002).
[CrossRef] [PubMed]

L. Novotny, "Effective wavelength scaling for optical antennas," Phys. Rev. Lett. 98,266802 (2007).
[CrossRef] [PubMed]

Proc. SPIE

P. Evanschitzky and A. Erdmann, "Three dimensional EUV simulations: A new mask near field and imaging simulationsystem," Proc. SPIE 5992,1546 (2005).

Other

www.drlitho.com

www.rit.edu/ 635dept5/thinfilms/thinfilms.htm

H. Raether, Surface Plasmons on Smooth and Rough Surfaces and on Gratings (Springer Verlag, Berlin, 1988).

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Figures (7)

Fig. 1.
Fig. 1.

Geometry of the investigated structure: Periodic array of slits (left) and posts (right).

Fig. 2.
Fig. 2.

Relative transmission T rel of a periodic array of slits in a silver film for different fill factors. The gray horizontal line corresponds to the wavelength in air (633 nm, dashed) and in the substrate (435 nm, solid). The curved black line specifies the thickness dependent surface plasmon wavelength [2].

Fig. 3.
Fig. 3.

Relative transmission T rel of a periodic array of slits in a silver film for different thicknesses t. m indicates the constant ridge width of the hyperbolas, where the transmission is minimal. The gray horizontal lines are specified as in Fig. 2.

Fig. 4.
Fig. 4.

Transmission T, reflection R and absorption A of an array of slits versus the wavelength for different values of the thickness t. The dashed lines show the values for metal layers without patterning. Pitch p and fill factor f correspond to the maximal relative transmission value according to Fig. 3.

Fig. 5.
Fig. 5.

Relative transmission of an array of posts (right) in a 30 nm thin silver film. The horizontal lines are specified as in Fig. 2. The dashed hyperbola denotes the region of a constant ridge width m = 140 nm.

Fig. 6.
Fig. 6.

Field distribution |E|2 of a contact hole (pitch 3840 nm, aperture width 960 nm) in a 30 nm thick silver film with different micro structuring. Polarization in y-direction. First row: structure geometry, second row: field 1 nm below the metal film (near field), third row: field 100 nm below the metal film (almost far field).

Fig. 7.
Fig. 7.

Transmission (blue curve) of an array of posts (p = 200 nm, f = 0.8, t = 30 nm) with different topography variations as shown in the inset sketches. The dashed horizontal line depicts the bulk transmission of a 30nm silver film. The dotted red line in the right figure shows the transmission through a silver film with the thickness of the material in the trenches.

Equations (5)

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kSP,x=kεdεmεd+εm,
Trel=TbulkTTbulk+T ,
kSP,zdm=kεdmεm+εd,
m5t+0.2λ72nm.
m4.3t+0.16λ72nm.

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