Abstract

Many applications, such as semiconductor lithography and material processing, require the shaping of laser beams to provide a homogenous field illumination. We present the conception, implementation, and experimental verification of a combined single-element homogenizer. Additionally, for excimer laser applications, the concept is associated with a coherence scrambling capability. We used the technique of holographic interference lithography to integrate the multifunctional properties in a diffractive optical element. The wavelength difference between the recording process (457.9  nm) and the application (193  nm) results in a change of the imaging properties and requires a geometrical adaptation of the optical setup. The coherence scrambling effect of the setup is based on an off-axis design, including the beam shaping diffractive structure.

© 2007 Optical Society of America

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  1. P. Michaloski, "Illuminators for microlithography," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 1-54.
  2. K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
    [CrossRef]
  3. L. Erdmann, M. Burkhardt, and R. Brunner, "Coherence management for microlens laser beam homogenizer," Proc. SPIE 4775, 145-154 (2002).
    [CrossRef]
  4. R. N. Gast, "Excimer laser photorefractive surgery of the cornea," Proc. SPIE 3343, 212-220 (1998).
    [CrossRef]
  5. E. G. Loewen and E. Popov, Diffraction Gratings and Applications (Dekker, 1997).
  6. R. Brunner, R. Steiner, K. Rudolf, and H.-J. Dobschal, "Diffractive-refractive hybrid microscope objective for 193 nm inspection systems," Proc. SPIE 5177, 9-15 (2003).
    [CrossRef]
  7. R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
    [CrossRef]
  8. A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
    [CrossRef]
  9. J. P. Sercel and M. von Dadelszen, "Practical UV excimer laser image system illuminators," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 113-156.
  10. T. Henning, L. Unnebrink, and M. Scholl, "UV laser beam shaping by multifaceted beam integrators: fundamental principles and advanced design concepts," Proc. SPIE 2703, 62-73 (1996).
    [CrossRef]
  11. P. Dainesi, J. Ihlemann, and P. Simon, "Optimization of a beam delivery system for a short-pulse KrF laser used for material ablation," Appl. Opt. 36, 7080-7085 (1997).
    [CrossRef]
  12. T. Sandström, "Homogenization of a spatially coherent radiation beam and printing and inspection, respectively, of a pattern on a workpiece," WO-Patent 03/023833 (20 March 2003).
  13. F. M. Dickey and S. C. Holswade, "Beam shaping: a review," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 269-306.

2006

P. Michaloski, "Illuminators for microlithography," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 1-54.

J. P. Sercel and M. von Dadelszen, "Practical UV excimer laser image system illuminators," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 113-156.

F. M. Dickey and S. C. Holswade, "Beam shaping: a review," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 269-306.

2003

T. Sandström, "Homogenization of a spatially coherent radiation beam and printing and inspection, respectively, of a pattern on a workpiece," WO-Patent 03/023833 (20 March 2003).

R. Brunner, R. Steiner, K. Rudolf, and H.-J. Dobschal, "Diffractive-refractive hybrid microscope objective for 193 nm inspection systems," Proc. SPIE 5177, 9-15 (2003).
[CrossRef]

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

2002

L. Erdmann, M. Burkhardt, and R. Brunner, "Coherence management for microlens laser beam homogenizer," Proc. SPIE 4775, 145-154 (2002).
[CrossRef]

1998

R. N. Gast, "Excimer laser photorefractive surgery of the cornea," Proc. SPIE 3343, 212-220 (1998).
[CrossRef]

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

1997

1996

T. Henning, L. Unnebrink, and M. Scholl, "UV laser beam shaping by multifaceted beam integrators: fundamental principles and advanced design concepts," Proc. SPIE 2703, 62-73 (1996).
[CrossRef]

Bläsi, B.

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Brunner, R.

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

R. Brunner, R. Steiner, K. Rudolf, and H.-J. Dobschal, "Diffractive-refractive hybrid microscope objective for 193 nm inspection systems," Proc. SPIE 5177, 9-15 (2003).
[CrossRef]

L. Erdmann, M. Burkhardt, and R. Brunner, "Coherence management for microlens laser beam homogenizer," Proc. SPIE 4775, 145-154 (2002).
[CrossRef]

Burkhardt, M.

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

L. Erdmann, M. Burkhardt, and R. Brunner, "Coherence management for microlens laser beam homogenizer," Proc. SPIE 4775, 145-154 (2002).
[CrossRef]

Choi, S.-S.

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

Chung, H. B.

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

Dainesi, P.

Dickey, F. M.

F. M. Dickey and S. C. Holswade, "Beam shaping: a review," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 269-306.

Dobschal, H.-J.

R. Brunner, R. Steiner, K. Rudolf, and H.-J. Dobschal, "Diffractive-refractive hybrid microscope objective for 193 nm inspection systems," Proc. SPIE 5177, 9-15 (2003).
[CrossRef]

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

Erdmann, L.

L. Erdmann, M. Burkhardt, and R. Brunner, "Coherence management for microlens laser beam homogenizer," Proc. SPIE 4775, 145-154 (2002).
[CrossRef]

Gast, R. N.

R. N. Gast, "Excimer laser photorefractive surgery of the cornea," Proc. SPIE 3343, 212-220 (1998).
[CrossRef]

Gombert, A.

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Heinzel, A.

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Helgert, M.

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

Henning, T.

T. Henning, L. Unnebrink, and M. Scholl, "UV laser beam shaping by multifaceted beam integrators: fundamental principles and advanced design concepts," Proc. SPIE 2703, 62-73 (1996).
[CrossRef]

Holswade, S. C.

F. M. Dickey and S. C. Holswade, "Beam shaping: a review," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 269-306.

Horbelt, W.

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Ihlemann, J.

Kim, B. W.

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

Kim, D. H.

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

Kim, J. S.

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

Lee, K. H.

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

Loewen, E. G.

E. G. Loewen and E. Popov, Diffraction Gratings and Applications (Dekker, 1997).

Martin, D.

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

Michaloski, P.

P. Michaloski, "Illuminators for microlithography," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 1-54.

Popov, E.

E. G. Loewen and E. Popov, Diffraction Gratings and Applications (Dekker, 1997).

Rose, K.

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Rudolf, K.

R. Brunner, R. Steiner, K. Rudolf, and H.-J. Dobschal, "Diffractive-refractive hybrid microscope objective for 193 nm inspection systems," Proc. SPIE 5177, 9-15 (2003).
[CrossRef]

Sandström, T.

T. Sandström, "Homogenization of a spatially coherent radiation beam and printing and inspection, respectively, of a pattern on a workpiece," WO-Patent 03/023833 (20 March 2003).

Scholl, M.

T. Henning, L. Unnebrink, and M. Scholl, "UV laser beam shaping by multifaceted beam integrators: fundamental principles and advanced design concepts," Proc. SPIE 2703, 62-73 (1996).
[CrossRef]

Sercel, J. P.

J. P. Sercel and M. von Dadelszen, "Practical UV excimer laser image system illuminators," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 113-156.

Simon, P.

Steiner, R.

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

R. Brunner, R. Steiner, K. Rudolf, and H.-J. Dobschal, "Diffractive-refractive hybrid microscope objective for 193 nm inspection systems," Proc. SPIE 5177, 9-15 (2003).
[CrossRef]

Unnebrink, L.

T. Henning, L. Unnebrink, and M. Scholl, "UV laser beam shaping by multifaceted beam integrators: fundamental principles and advanced design concepts," Proc. SPIE 2703, 62-73 (1996).
[CrossRef]

von Dadelszen, M.

J. P. Sercel and M. von Dadelszen, "Practical UV excimer laser image system illuminators," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 113-156.

Wittwer, V.

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Yoo, H. Y.

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

Zanke, Ch.

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Appl. Opt.

Proc. SPIE

T. Henning, L. Unnebrink, and M. Scholl, "UV laser beam shaping by multifaceted beam integrators: fundamental principles and advanced design concepts," Proc. SPIE 2703, 62-73 (1996).
[CrossRef]

K. H. Lee, D. H. Kim, J. S. Kim, S.-S. Choi, H. B. Chung, H. Y. Yoo, and B. W. Kim, "Design of illumination system for ArF excimer laser step-and-scanner," Proc. SPIE 3334, 997-1004 (1998).
[CrossRef]

L. Erdmann, M. Burkhardt, and R. Brunner, "Coherence management for microlens laser beam homogenizer," Proc. SPIE 4775, 145-154 (2002).
[CrossRef]

R. N. Gast, "Excimer laser photorefractive surgery of the cornea," Proc. SPIE 3343, 212-220 (1998).
[CrossRef]

R. Brunner, R. Steiner, K. Rudolf, and H.-J. Dobschal, "Diffractive-refractive hybrid microscope objective for 193 nm inspection systems," Proc. SPIE 5177, 9-15 (2003).
[CrossRef]

R. Brunner, R. Steiner, H.-J. Dobschal, D. Martin, M. Burkhardt, and M. Helgert, "New solutions to realize complex optical systems by a combination of diffractive and refractive optical components," Proc. SPIE 5183, 47-55 (2003).
[CrossRef]

Solar Energy Mater. Sol. Cells

A. Gombert, K. Rose, A. Heinzel, W. Horbelt, Ch. Zanke, B. Bläsi, and V. Wittwer, "Antireflective submicrometer surface-relief gratings for solar applications," Solar Energy Mater. Sol. Cells 54, 333-342 (1998).
[CrossRef]

Other

J. P. Sercel and M. von Dadelszen, "Practical UV excimer laser image system illuminators," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 113-156.

E. G. Loewen and E. Popov, Diffraction Gratings and Applications (Dekker, 1997).

P. Michaloski, "Illuminators for microlithography," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 1-54.

T. Sandström, "Homogenization of a spatially coherent radiation beam and printing and inspection, respectively, of a pattern on a workpiece," WO-Patent 03/023833 (20 March 2003).

F. M. Dickey and S. C. Holswade, "Beam shaping: a review," in Laser Beam Shaping Applications, F. M. Dickey, S. C. Holswade, and D. L. Shealy, eds. (Taylor & Francis Group, 2006), pp. 269-306.

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Figures (7)

Fig. 1
Fig. 1

Working principle of a classical nonimaging fly's eye homogenizer. The incident laser beam is split by the lens array into several beamlets, which are superposed by the condensor lens in the target plane.

Fig. 2
Fig. 2

Setup for the holographic recording. The object wavefront (spherical wave modulated by the lenslets) interferes with an off-axis reference plane wave. Note that the reference for angle φ is only valid for the center beam of the object wave. The encircled part represents the scheme of recording the surface structure by interference lithography. The lines of minimum intensity defining the facets of the profile are determined by the bisector of the local wave vectors.

Fig. 3
Fig. 3

Application setup. The UV laser is adjusted on the opposite side of the hologram. Due to the wavelength shift from recording to reconstruction, the inclination angle has to be adapted. The encircled part shows the variation of the period in the y direction. Due to the off-axis recording setup the distribution of the local period is asymmetrical.

Fig. 4
Fig. 4

Distribution of the spatial periods of the recorded hologram. The structure is characterized by a scalelike pattern showing major steps and minor discontinuities in orthogonal directions. The boundaries of the individual scales correlate with the initial lenslets of the array. In the plot, the period distribution of the inner 7 × 10 lenslets is included. To emphasize the topography, a lighting effect with a source from the right was applied to the plot. Discontinuities are partially flattened by the limited number of 251 × 251 sampling points.

Fig. 5
Fig. 5

(a) Grayscale image of the field distribution when the excimer laser is used without modification. (b) Corresponding cross sections.

Fig. 6
Fig. 6

(a) Grayscale image of the field distribution when the excimer laser is expanded by a factor of two. The longer coherence length of the laser is orientated along the y direction of the image. The transversal coherence length is longer than the corresponding pitch dimension in the y direction. The fringe modulation arise due to the coherent superposition of the adjacent beamlets. (b) Corresponding cross sections.

Fig. 7
Fig. 7

(a) Grayscale image of the field distribution measured under equivalent conditions of Fig. 6 but with 90° rotation of the laser beam with respect to the holographic homogenizer. The longer coherence length of the laser is orientated along the x direction of the image. The anticipated interference modulation in the x direction is suppressed by the coherence scrambling effect. (b) Cross section of the intensity patterns corresponding to Fig. 7(a). Due to the delay of adjacent beamlets effecting the long transversal coherence length, coherence scrambling is introduced.

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

D = | p F f | .
N F p D 4 λ F .
Λ ( r ) = λ r e c 2 sin φ 458 2 ( r ) cos θ ( r ) .

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