Abstract

The accurate determination of critical dimensions and roughness is necessary to ensure the quality of photoresist masks that are crucial for the operational reliability of electronic components. Scatterometry provides a fast indirect optical nondestructive method for the determination of profile parameters that are obtained from scattered light intensities using inverse methods. We illustrate the effect of line roughness on the reconstruction of grating parameters employing a maximum likelihood scheme. Neglecting line roughness introduces a strong bias in the parameter estimations. Therefore, such roughness has to be included in the mathematical model of the measurement in order to obtain accurate reconstruction results. In addition, the method allows to determine line roughness from scatterometry. The approach is demonstrated for simulated scattering intensities as well as for experimental data of extreme ultraviolet light scatterometry measurements. The results obtained from the experimental data are in agreement with independent atomic force microscopy measurements.

© 2012 Optical Society of America

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  2. C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
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  4. F. Scholze and C. Laubis, Proc. SPIE 6792, 67920U (2008).
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]

2012 (3)

2010 (1)

2009 (1)

T. Schuster, S. Rafler, V. F. Paz, F. Frenner, and W. Osten, Microelectron. Eng. 86, 1029 (2009).
[CrossRef]

2008 (2)

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

F. Scholze and C. Laubis, Proc. SPIE 6792, 67920U (2008).
[CrossRef]

2007 (1)

2004 (3)

B. D. Bunday, M. Bishop, and D. McCormack, Proc. SPIE 5375, 515 (2004).
[CrossRef]

J. Perlich, F. Kamm, J. Rau, F. Scholze, and G. Ulm, J. Vac. Sci. Technol. B 22, 3059 (2004).
[CrossRef]

H. Huang and F. Terry, Thin Solid Films 455, 828 (2004).
[CrossRef]

1997 (1)

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

Bär, M.

Bishop, M.

B. D. Bunday, M. Bishop, and D. McCormack, Proc. SPIE 5375, 515 (2004).
[CrossRef]

Bunday, B. D.

B. D. Bunday, M. Bishop, and D. McCormack, Proc. SPIE 5375, 515 (2004).
[CrossRef]

Burger, S.

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

Chen, W.-Y.

W.-Y. Chen and C.-H. Lin, Thin Solid Films 522, 79 (2012).
[CrossRef]

Dersch, U.

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

Elster, C.

Frenner, F.

T. Schuster, S. Rafler, V. F. Paz, F. Frenner, and W. Osten, Microelectron. Eng. 86, 1029 (2009).
[CrossRef]

Germer, T. A.

Gross, H.

Heidenreich, S.

Henn, M.-A.

Horsch, J.

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

Huang, H.

H. Huang and F. Terry, Thin Solid Films 455, 828 (2004).
[CrossRef]

Kamm, F.

J. Perlich, F. Kamm, J. Rau, F. Scholze, and G. Ulm, J. Vac. Sci. Technol. B 22, 3059 (2004).
[CrossRef]

Kato, A.

Laubis, C.

F. Scholze and C. Laubis, Proc. SPIE 6792, 67920U (2008).
[CrossRef]

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

Lin, C.-H.

W.-Y. Chen and C.-H. Lin, Thin Solid Films 522, 79 (2012).
[CrossRef]

Mc Neil, J.

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

McCormack, D.

B. D. Bunday, M. Bishop, and D. McCormack, Proc. SPIE 5375, 515 (2004).
[CrossRef]

Millar, R.

R. Millar, Maximum Likelihood Estimation and Inference(Wiley, 2011).

Murane, M.

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

Navi, H.

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

Osten, W.

T. Schuster, S. Rafler, V. F. Paz, F. Frenner, and W. Osten, Microelectron. Eng. 86, 1029 (2009).
[CrossRef]

Paz, V. F.

T. Schuster, S. Rafler, V. F. Paz, F. Frenner, and W. Osten, Microelectron. Eng. 86, 1029 (2009).
[CrossRef]

Perlich, J.

J. Perlich, F. Kamm, J. Rau, F. Scholze, and G. Ulm, J. Vac. Sci. Technol. B 22, 3059 (2004).
[CrossRef]

Pomplun, J.

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

Prins, S.

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

Rafler, S.

T. Schuster, S. Rafler, V. F. Paz, F. Frenner, and W. Osten, Microelectron. Eng. 86, 1029 (2009).
[CrossRef]

Rathsfeld, A.

Rau, J.

J. Perlich, F. Kamm, J. Rau, F. Scholze, and G. Ulm, J. Vac. Sci. Technol. B 22, 3059 (2004).
[CrossRef]

Raymond, C.

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

Schmidt, F.

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

Scholze, F.

M.-A. Henn, H. Gross, F. Scholze, M. Wurm, C. Elster, and M. Bär, Opt. Express 20, 12771 (2012).
[CrossRef]

A. Kato and F. Scholze, Appl. Opt. 49, 6102 (2010).
[CrossRef]

F. Scholze and C. Laubis, Proc. SPIE 6792, 67920U (2008).
[CrossRef]

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

J. Perlich, F. Kamm, J. Rau, F. Scholze, and G. Ulm, J. Vac. Sci. Technol. B 22, 3059 (2004).
[CrossRef]

Schuster, T.

T. Schuster, S. Rafler, V. F. Paz, F. Frenner, and W. Osten, Microelectron. Eng. 86, 1029 (2009).
[CrossRef]

Sohail, S.

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

Terry, F.

H. Huang and F. Terry, Thin Solid Films 455, 828 (2004).
[CrossRef]

Ulm, G.

J. Perlich, F. Kamm, J. Rau, F. Scholze, and G. Ulm, J. Vac. Sci. Technol. B 22, 3059 (2004).
[CrossRef]

Wurm, M.

Appl. Opt. (2)

J. Opt. Soc. Am. A (1)

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

C. Raymond, M. Murane, S. Prins, S. Sohail, H. Navi, J. Mc Neil, and J. Horsch, J. Vac. Sci. Technol. B 15, 361 (1997).
[CrossRef]

J. Perlich, F. Kamm, J. Rau, F. Scholze, and G. Ulm, J. Vac. Sci. Technol. B 22, 3059 (2004).
[CrossRef]

Microelectron. Eng. (1)

T. Schuster, S. Rafler, V. F. Paz, F. Frenner, and W. Osten, Microelectron. Eng. 86, 1029 (2009).
[CrossRef]

Opt. Express (1)

Proc. SPIE (3)

F. Scholze and C. Laubis, Proc. SPIE 6792, 67920U (2008).
[CrossRef]

J. Pomplun, S. Burger, F. Schmidt, F. Scholze, C. Laubis, and U. Dersch, Proc. SPIE 7028, 70280P (2008).
[CrossRef]

B. D. Bunday, M. Bishop, and D. McCormack, Proc. SPIE 5375, 515 (2004).
[CrossRef]

Thin Solid Films (2)

W.-Y. Chen and C.-H. Lin, Thin Solid Films 522, 79 (2012).
[CrossRef]

H. Huang and F. Terry, Thin Solid Films 455, 828 (2004).
[CrossRef]

Other (2)

R. Millar, Maximum Likelihood Estimation and Inference(Wiley, 2011).

J. Elschner, R. Hinder, A. Rathsfeld, and G. Schmidt, http://www.wias-berlin.de/software /DIPOG .

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Figures (3)

Fig. 1.
Fig. 1.

(a) EUV-mask geometry with 280 nm pitch. Angle between the horizontal line and the sidewall of TaN layer is called sidewall angle (SWA); design value is 90°. (b) Sketch of line edge and linewidth roughness (LEWR). Line positions and widths are varying randomly around periodic design values within computational domains containing 24 lines.

Fig. 2.
Fig. 2.

Profile reconstructions for the sidewall angle (SWA, upper panels) and the top width (top CD, lower panels). (a) Boxplots of a set of 100 reconstructions. Reference efficiency data are obtained by simulations of super cells with added noise. The green dashed lines indicate mean reference values. Model 1 (without roughness) yields a strong systematic bias from 90 deg for SWA and from 93.3 nm for top CD. Model 2 (with roughness) are distributed closely around reference values. (b) Boxplots of a set of 10 experimental data. The green dashed lines give averaged values of atomic force microscope measurements on an adjacent feature on the same mask [13]. Lower panel shows deviations of design values 180 and 540 nm, respectively. Model 1 shows unrealistic under etching (>90deg), small bias of the top CD and asymmetric distributions. Model 2, reconstructions are close to AFM measurements (boxes include 50% of all reconstructions, red line gives the median).

Fig. 3.
Fig. 3.

Determination of roughness variance σΔ form numerically calculated values and experimental data. (a) The mean value is close to the expected value σeff=6.26nm (green dashed line). (b) Roughness is in a magnitude typical for EUV masks [13].

Tables (1)

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Table 1. Mean Values and Standard Deviations

Equations (5)

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Δu(x,y)+k2(x,y)u(x,y)=0,
L(a,b,p)=j=1m12πσjexp[(fj(p)yj)22σj2].
θ^=argmaxa,b,pL(a,b,p).
f˜(p)j=exp(σΔ2kj2)fj(p).
σΔ2σeff2=σLER2+σLWR2/4.

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