Abstract

In optical lithography the degradation of image quality due to aberrations present in the exposure tool is a serious problem. Therefore it is desirable to establish a reliable aberration measurement procedure based on the analysis of printed images in the photoresist. We present what is to our knowledge a new method for characterizing the aberrations of an exposure tool using a hybrid diffractive photomask. By utilizing each different impact on the aberrated image from each diffracted illumination, we were able to extract the aberration present in the stepper system. We experimentally verified this method with a G-line stepper and verified its spherical aberration astigmatism.

© 2003 Optical Society of America

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References

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  1. T. Brunner, “Impact of lens aberrations on optical lithography,” IBM J. Res. Dev. 41, 57–67 (1997).
    [CrossRef]
  2. M. Born, E. Wolf, Principles of Optics, 6th ed. (Pergamon, Oxford, 1980), pp. 459–490.
  3. A. K. K. Wong, Resolution Enhancement Techniques in Optical Lithography, TT47 (SPIE Press, Bellingham, Wash.2001) Chap. 2.
    [CrossRef]
  4. J. P. Kirk, “Measurement of astigmatism in microlithography lenses”, in Optical Lithography 11, L. V. den Hove, ed., Proc. SPIE3334, 848–854 (1998)
  5. M. S. Yeung, “Measurement of wave-front aberrations in high-resolution optical lithographic systems from printed photoresist patterns,” IEEE Trans. Semicond. Manuf. 13, 24–32 (2000).
    [CrossRef]
  6. H. Nomura, T. Sato, “Techniques for measuring aberrations in lenses used in photolithography with printed patterns,” Appl. Opt. 38, 2800–2807 (1999).
    [CrossRef]
  7. J. P. Kirk, G. Kunkel, A. K. Wong, “Aberration measurement using in-situ two beam interferometry,” in Optical Microlithography 14, (Proc. SPIE, 4346, Bellingham, Wash., 2001) pp. 8–14.
    [CrossRef]
  8. H. Nomura, “New phase-shift gratings for measuring aberrations,” in Optical Microlithography 14, (Proc. SPIE, 4346, Bellingham, Wash, 2001) pp. 25–35.
    [CrossRef]
  9. H. Nomura, K. Tawarayama, T. Kohno, “Aberration measurement from specific photolithographic images: a different approach,” Appl. Opt. 39, 1136–1147 (2000).
    [CrossRef]
  10. G. H. Golub, C. H. van Loan, Matrix Computations, 3rd ed. (Johns Hopkins U. Press, Baltimore, Md.1996).

2000

M. S. Yeung, “Measurement of wave-front aberrations in high-resolution optical lithographic systems from printed photoresist patterns,” IEEE Trans. Semicond. Manuf. 13, 24–32 (2000).
[CrossRef]

H. Nomura, K. Tawarayama, T. Kohno, “Aberration measurement from specific photolithographic images: a different approach,” Appl. Opt. 39, 1136–1147 (2000).
[CrossRef]

1999

1997

T. Brunner, “Impact of lens aberrations on optical lithography,” IBM J. Res. Dev. 41, 57–67 (1997).
[CrossRef]

Born, M.

M. Born, E. Wolf, Principles of Optics, 6th ed. (Pergamon, Oxford, 1980), pp. 459–490.

Brunner, T.

T. Brunner, “Impact of lens aberrations on optical lithography,” IBM J. Res. Dev. 41, 57–67 (1997).
[CrossRef]

Golub, G. H.

G. H. Golub, C. H. van Loan, Matrix Computations, 3rd ed. (Johns Hopkins U. Press, Baltimore, Md.1996).

Kirk, J. P.

J. P. Kirk, “Measurement of astigmatism in microlithography lenses”, in Optical Lithography 11, L. V. den Hove, ed., Proc. SPIE3334, 848–854 (1998)

J. P. Kirk, G. Kunkel, A. K. Wong, “Aberration measurement using in-situ two beam interferometry,” in Optical Microlithography 14, (Proc. SPIE, 4346, Bellingham, Wash., 2001) pp. 8–14.
[CrossRef]

Kohno, T.

Kunkel, G.

J. P. Kirk, G. Kunkel, A. K. Wong, “Aberration measurement using in-situ two beam interferometry,” in Optical Microlithography 14, (Proc. SPIE, 4346, Bellingham, Wash., 2001) pp. 8–14.
[CrossRef]

Nomura, H.

Sato, T.

Tawarayama, K.

van Loan, C. H.

G. H. Golub, C. H. van Loan, Matrix Computations, 3rd ed. (Johns Hopkins U. Press, Baltimore, Md.1996).

Wolf, E.

M. Born, E. Wolf, Principles of Optics, 6th ed. (Pergamon, Oxford, 1980), pp. 459–490.

Wong, A. K.

J. P. Kirk, G. Kunkel, A. K. Wong, “Aberration measurement using in-situ two beam interferometry,” in Optical Microlithography 14, (Proc. SPIE, 4346, Bellingham, Wash., 2001) pp. 8–14.
[CrossRef]

Wong, A. K. K.

A. K. K. Wong, Resolution Enhancement Techniques in Optical Lithography, TT47 (SPIE Press, Bellingham, Wash.2001) Chap. 2.
[CrossRef]

Yeung, M. S.

M. S. Yeung, “Measurement of wave-front aberrations in high-resolution optical lithographic systems from printed photoresist patterns,” IEEE Trans. Semicond. Manuf. 13, 24–32 (2000).
[CrossRef]

Appl. Opt.

IBM J. Res. Dev.

T. Brunner, “Impact of lens aberrations on optical lithography,” IBM J. Res. Dev. 41, 57–67 (1997).
[CrossRef]

IEEE Trans. Semicond. Manuf.

M. S. Yeung, “Measurement of wave-front aberrations in high-resolution optical lithographic systems from printed photoresist patterns,” IEEE Trans. Semicond. Manuf. 13, 24–32 (2000).
[CrossRef]

Other

M. Born, E. Wolf, Principles of Optics, 6th ed. (Pergamon, Oxford, 1980), pp. 459–490.

A. K. K. Wong, Resolution Enhancement Techniques in Optical Lithography, TT47 (SPIE Press, Bellingham, Wash.2001) Chap. 2.
[CrossRef]

J. P. Kirk, “Measurement of astigmatism in microlithography lenses”, in Optical Lithography 11, L. V. den Hove, ed., Proc. SPIE3334, 848–854 (1998)

G. H. Golub, C. H. van Loan, Matrix Computations, 3rd ed. (Johns Hopkins U. Press, Baltimore, Md.1996).

J. P. Kirk, G. Kunkel, A. K. Wong, “Aberration measurement using in-situ two beam interferometry,” in Optical Microlithography 14, (Proc. SPIE, 4346, Bellingham, Wash., 2001) pp. 8–14.
[CrossRef]

H. Nomura, “New phase-shift gratings for measuring aberrations,” in Optical Microlithography 14, (Proc. SPIE, 4346, Bellingham, Wash, 2001) pp. 25–35.
[CrossRef]

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Figures (9)

Fig. 1
Fig. 1

Optical diagram of the photolithographic stepper.

Fig. 2
Fig. 2

Three-beam interference imaging through the pupil (H. Nomura, T. Sato6).

Fig. 3
Fig. 3

Binary phase diffractive profile and generated illumination patterns at the pupil: (a) circular plane, (b) square phase.

Fig. 4
Fig. 4

(a) Binary chrome mask, (b) 1X plate mask for patterning diffractive profile viewed from the top.

Fig. 5
Fig. 5

5. A simulated plot of line-width (CD) vs. defocus curves for many exposure doses (Bossung curves).

Fig. 6
Fig. 6

Microscope images of the fabricated diffractive masks: (a) circular phase grating, (b) square phase grating.

Fig. 7
Fig. 7

Microscope image of the printed focus micro-step exposure.

Fig. 8
Fig. 8

Bossung curves for three illumination cases obtained from the SEM measurement: (a) from conventional illumination, (b) quadrupole illumination, (c) annular illumination.

Fig. 9
Fig. 9

(a) Reconstructed wave front at the pupil, (b) simulated image of a line grating of 0.8λ of the line width.

Tables (4)

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Table 1 Aerial Image Calculation Algorithm

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Table 2 Focus Data Obtained From the Bossung Curves for Three Illuminations

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Table 3 Aberration Sensitivity Matrices Determined From the Aerial Image Simulationa

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Table 4 Zernike Coefficients Obtained for Astigmatism and Spherical Aberration From Our Measurement

Equations (11)

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Ĥfˆ, ĝ=H fˆ, ĝexpi 2πλ Wρ, θ,
fc=f2=12p.
Si,j=BFiZj,
Si,j=HV cosθiZj.
ΔBFi=BFiZ4 Z4+BFiZ9 Z9+BFiZ16 Z16,
λ1-σNA  p  3λ1 + σNA.
Ix,Δz=|A0+A1expjϕ1-expj2πxρ+A-1expjϕ-1exp-j2πx|2=A02+4A12cos22πxp+ϕ1-ϕ-12+4A0A1cos2πxp+ϕ1-ϕ-12cosϕ1+ϕ-12+κΔz.
X = S¯ · Z.
X = ΔBF1ΔBF2ΔBF3 = -0.25-0.30-0.10 = -5.010.5-9.0-6.011.3-7.5-5.010.5-7.0 · Z4Z9Z16Z9=0.1904λ, Z16=0.0752λ  (third and fifth order).
X = HVcosθ1HVcosθ2HVcosθ3=0.3620.3420.20 = 12.08-8.305.712.08-8.565.912.08-7.643.1 · Z4Z5Z12  Z5 = 0.1706λ, Z12 = 0.1068λ (third and fifth order).
fc2+ gc2  σ2 NA2 / λ2

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