Abstract

The choice of the operational wavelength for a soft-x-ray projection lithography system affects a wide variety of system parameters such as optical design, sources, resists, and multilayer mirrors. Several system constraints limit the choice for the operational wavelength. In particular, optical imaging requirements place an upper limit and throughput issues place a lower limit on the wavelength selection. We have determined that there are several discrete wavelength regions between 10 and 25 nm that satisfy the system-imposed constraints of high resolution, large depth of focus, and high throughput.

© 1993 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. N. M. Ceglio, A. M. Hawryluk, “Soft x-ray projection lithography system design,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 82–101 (1991).
  2. J. Ruffer, “Fabrication and characterization of Be-based multilayer mirrors,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 176–187 (1991).
  3. E. J. Puik, “Ni-Cr multilayer coatings,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 221–228 (1991).
  4. P. A. Kearney, J. Slaughter, C. Falco, “Boron based multilayers,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 63–71 (1991).
  5. B. Newnam, “XUV free electron laser-based systems,” in X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry and Projection Lithography, R. B. Hoover, A. B. Walker, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1343, 214–229 (1990).
  6. H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.
  7. B. Newnam, “Development of free electron lasers for XUV,” in Free-Electron Lasers and Applications, D. Prosnitz, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1227, 116–133 (1990).
  8. K. Nguyen, D. Attwood, T. Gustafson, “Source issues relevant to x-ray lithography,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 62–68.
  9. S. Okazaki, “Resolution limits of optical lithography,” J. Vac. Sci. Technol. B 9, 2829–2834 (1991).
    [CrossRef]
  10. D. Stearns, Lawrence Livermore National Laboratory, Livermore, Calif. 94551 (personal communication, 1992).
  11. A. M. Hawryluk, N. M. Ceglio, “Power loading limitations in soft x-ray projection lithography,” J. X-Ray Sci. (to be published).
  12. ULE is an ultralow-expansion material from Du Pont.
  13. D. Markle, Ultratech Stepper, Santa Clara, Calif. 95054 (personal communication, 1991).
  14. D. E. Andrews, M. M. Wilson, “High energy lithography illumination by Oxford’s synchrotron,” J. Vac. Sci. Technol. B 7, 1696–1702 (1989).
    [CrossRef]
  15. R. L. Kauffman, D. W. Phillion, R. Spitzer, “X-ray production ~ 130 Å from laser-produced plasmas for projection x-ray lithography applications,” in Soft-X-Ray Projection Lithography, Vol. 8 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D. C., 1992), p. 17.
  16. D. Hofer, IBM Almaden Research Laboratory, San Jose, Calif. 95120 (personal communication, 1992).

1991 (1)

S. Okazaki, “Resolution limits of optical lithography,” J. Vac. Sci. Technol. B 9, 2829–2834 (1991).
[CrossRef]

1989 (1)

D. E. Andrews, M. M. Wilson, “High energy lithography illumination by Oxford’s synchrotron,” J. Vac. Sci. Technol. B 7, 1696–1702 (1989).
[CrossRef]

Andrews, D. E.

D. E. Andrews, M. M. Wilson, “High energy lithography illumination by Oxford’s synchrotron,” J. Vac. Sci. Technol. B 7, 1696–1702 (1989).
[CrossRef]

Attwood, D.

K. Nguyen, D. Attwood, T. Gustafson, “Source issues relevant to x-ray lithography,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 62–68.

Ceglio, N. M.

N. M. Ceglio, A. M. Hawryluk, “Soft x-ray projection lithography system design,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 82–101 (1991).

A. M. Hawryluk, N. M. Ceglio, “Power loading limitations in soft x-ray projection lithography,” J. X-Ray Sci. (to be published).

Falco, C.

P. A. Kearney, J. Slaughter, C. Falco, “Boron based multilayers,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 63–71 (1991).

Gustafson, T.

K. Nguyen, D. Attwood, T. Gustafson, “Source issues relevant to x-ray lithography,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 62–68.

Haga, T.

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

Hawryluk, A. M.

N. M. Ceglio, A. M. Hawryluk, “Soft x-ray projection lithography system design,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 82–101 (1991).

A. M. Hawryluk, N. M. Ceglio, “Power loading limitations in soft x-ray projection lithography,” J. X-Ray Sci. (to be published).

Hofer, D.

D. Hofer, IBM Almaden Research Laboratory, San Jose, Calif. 95120 (personal communication, 1992).

Ishii, Y.

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

Kauffman, R. L.

R. L. Kauffman, D. W. Phillion, R. Spitzer, “X-ray production ~ 130 Å from laser-produced plasmas for projection x-ray lithography applications,” in Soft-X-Ray Projection Lithography, Vol. 8 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D. C., 1992), p. 17.

Kearney, P. A.

P. A. Kearney, J. Slaughter, C. Falco, “Boron based multilayers,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 63–71 (1991).

Kinoshita, H.

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

Kurihara, K.

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

Markle, D.

D. Markle, Ultratech Stepper, Santa Clara, Calif. 95054 (personal communication, 1991).

Mizota, T.

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

Newnam, B.

B. Newnam, “XUV free electron laser-based systems,” in X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry and Projection Lithography, R. B. Hoover, A. B. Walker, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1343, 214–229 (1990).

B. Newnam, “Development of free electron lasers for XUV,” in Free-Electron Lasers and Applications, D. Prosnitz, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1227, 116–133 (1990).

Nguyen, K.

K. Nguyen, D. Attwood, T. Gustafson, “Source issues relevant to x-ray lithography,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 62–68.

Okazaki, S.

S. Okazaki, “Resolution limits of optical lithography,” J. Vac. Sci. Technol. B 9, 2829–2834 (1991).
[CrossRef]

Phillion, D. W.

R. L. Kauffman, D. W. Phillion, R. Spitzer, “X-ray production ~ 130 Å from laser-produced plasmas for projection x-ray lithography applications,” in Soft-X-Ray Projection Lithography, Vol. 8 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D. C., 1992), p. 17.

Puik, E. J.

E. J. Puik, “Ni-Cr multilayer coatings,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 221–228 (1991).

Ruffer, J.

J. Ruffer, “Fabrication and characterization of Be-based multilayer mirrors,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 176–187 (1991).

Slaughter, J.

P. A. Kearney, J. Slaughter, C. Falco, “Boron based multilayers,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 63–71 (1991).

Spitzer, R.

R. L. Kauffman, D. W. Phillion, R. Spitzer, “X-ray production ~ 130 Å from laser-produced plasmas for projection x-ray lithography applications,” in Soft-X-Ray Projection Lithography, Vol. 8 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D. C., 1992), p. 17.

Stearns, D.

D. Stearns, Lawrence Livermore National Laboratory, Livermore, Calif. 94551 (personal communication, 1992).

Takenaka, H.

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

Torii, Y.

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

Wilson, M. M.

D. E. Andrews, M. M. Wilson, “High energy lithography illumination by Oxford’s synchrotron,” J. Vac. Sci. Technol. B 7, 1696–1702 (1989).
[CrossRef]

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

S. Okazaki, “Resolution limits of optical lithography,” J. Vac. Sci. Technol. B 9, 2829–2834 (1991).
[CrossRef]

D. E. Andrews, M. M. Wilson, “High energy lithography illumination by Oxford’s synchrotron,” J. Vac. Sci. Technol. B 7, 1696–1702 (1989).
[CrossRef]

Other (14)

R. L. Kauffman, D. W. Phillion, R. Spitzer, “X-ray production ~ 130 Å from laser-produced plasmas for projection x-ray lithography applications,” in Soft-X-Ray Projection Lithography, Vol. 8 of 1992 OSA Technical Digest Series (Optical Society of America, Washington, D. C., 1992), p. 17.

D. Hofer, IBM Almaden Research Laboratory, San Jose, Calif. 95120 (personal communication, 1992).

D. Stearns, Lawrence Livermore National Laboratory, Livermore, Calif. 94551 (personal communication, 1992).

A. M. Hawryluk, N. M. Ceglio, “Power loading limitations in soft x-ray projection lithography,” J. X-Ray Sci. (to be published).

ULE is an ultralow-expansion material from Du Pont.

D. Markle, Ultratech Stepper, Santa Clara, Calif. 95054 (personal communication, 1991).

N. M. Ceglio, A. M. Hawryluk, “Soft x-ray projection lithography system design,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 82–101 (1991).

J. Ruffer, “Fabrication and characterization of Be-based multilayer mirrors,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 176–187 (1991).

E. J. Puik, “Ni-Cr multilayer coatings,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 221–228 (1991).

P. A. Kearney, J. Slaughter, C. Falco, “Boron based multilayers,” in Multilayer Optics for Advanced X-Ray Applications, N. M. Ceglio, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1547, 63–71 (1991).

B. Newnam, “XUV free electron laser-based systems,” in X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry and Projection Lithography, R. B. Hoover, A. B. Walker, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1343, 214–229 (1990).

H. Kinoshita, K. Kurihara, T. Mizota, T. Haga, Y. Torii, H. Takenaka, Y. Ishii, “Soft-x-ray reduction lithography using a reflection mask,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 11–16.

B. Newnam, “Development of free electron lasers for XUV,” in Free-Electron Lasers and Applications, D. Prosnitz, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1227, 116–133 (1990).

K. Nguyen, D. Attwood, T. Gustafson, “Source issues relevant to x-ray lithography,” in Soft-X-Ray Projection Lithography, J. Bokor, ed., Vol. 12 of OSA Proceedings Series (Optical Society of America, Washington, D. C., 1991), pp. 62–68.

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (6)

Fig. 1
Fig. 1

Resolution and depth of focus are calculated from the wavelength and numerical aperture of the imaging system. To achieve a resolution less than 100 nm and a depth of focus greater than 500 nm simultaneously in an industrial environment will require that the wavelength be less than 28.5 nm.

Fig. 2
Fig. 2

Ideal (σ = 0) normal-incidence reflectivity for selected multilayers versus wavelength showing large local maximas at wavelengths slightly greater than the absorption edge for the low-Z material. The mirror reflectivity decreases quickly for wavelengths away from the absorption edges.

Fig. 3
Fig. 3

Practical multilayers with finite interface widths. The calculated x-ray reflectivity from multilayer mirrors with an interface parameter σ = 0 is compared with the calculated reflectivity from mirrors with an interface parameter σ = 3 Å.

Fig. 4
Fig. 4

Calculated x-ray sensitivity for a C-based resist as a function of wavelength as determined by scaling the resist sensitivity to the x-ray absorption depth.

Fig. 5
Fig. 5

Minimum mirror reflectivity limited by the total thermal distortion permitted on an imaging optic. In this calculation we assumed an optic material similar to ULE and a resist sensitivity as calculated in Fig. 4. For optics with an aspect ratio of 4:1, the minimum mirror reflectivity (assuming σ = 3 Å) is satisfied only for wavelengths greater than 6.8 nm.

Fig. 6
Fig. 6

Many resist processes require a minimum radiation absorption depth for minimizing pinhole defects. Assuming a minimum absorption depth of 50 nm, the maximum x-ray wavelength (for the resist in Fig. 4) is approximately 25 nm.

Tables (4)

Tables Icon

Table 1 Absorption Edges of Materials

Tables Icon

Table 2 Source Power Requirements

Tables Icon

Table 3 Synchrotron Bending Magnet Collection Angle Requirements for a Synchrotron Operatng at 0.7 GeV, 300 mA, and 4.5 T

Tables Icon

Table 4 Laser Driver Power Requirements Assuming η = 1% and dΩ = 0.2 sr

Equations (10)

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

R = k 1 λ / NA ,
DOF = k 2 λ / ( NA ) 2
T = P s R n W m / S ,
R = R 0 exp [ - ( 2 π σ / Λ ) 2 ] ,
Λ = λ / 2 [ 2 μ sin ( θ ) ] .
δ = ( 1.6 × 10 - 3 nm / mW ) q ( mW ) .
q ( mW ) = S ( λ ) T ( 1 - R ) / ( W R 4 ) ,
S ( λ = 1.4 nm ) / l a ( λ = 1.4 nm ) = S ( λ ) / l a ( λ ) ,
P s = S ( λ ) T / [ R 8 ( λ ) W 3 ] = 7.3 × 10 3 S ( λ ) / R 8 ( λ ) .
P laser ( W ) = P s / ( η d Ω / π ) = 1571 P s ( W ) ,

Metrics