Abstract

An original approach to measurement accuracy of a typical focus sensor in conventional integrated circuit lithographic equipment is introduced. Causes of measurement error in the focus sensor are theoretically analyzed and found to be generated mainly from interactions between imperfections of the optical system and the actual surface of processed wafers. We derive mathematical formulations describing these errors, which are confirmed by the experimental results performed by using an optical setup composed of the focus sensor and samples on which the wafer surface condition is reproduced. Furthermore, several novel techniques that are intended to reduce those measurement errors are successfully demonstrated.

© 2008 Optical Society of America

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References

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  1. J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
    [CrossRef]
  2. T. Matsuyama, Y. Ohmura, and D. M. Williamson, “The lithographic lens: its history and evolution,” Proc. SPIE 6154, 615403 (2006).
    [CrossRef]
  3. J. M. Bennett, V. Elings, and K. Kjoller, “Recent developments in profiling optical surfaces,” Appl. Opt. 32, 3442-3447 (1993).
    [CrossRef] [PubMed]
  4. F. Chen, G. M. Brown, and M. Song, “Overview of three-dimensional shape measurement using optical methods,” Opt. Eng. (Bellingham) 39, 10-22 (2000).
    [CrossRef]
  5. F. Blais, “Review of 20 years of range sensor development,” J. Electron. Imaging 13, 231-243 (2004).
    [CrossRef]
  6. P. J. Besl, “Active, optical range imaging sensors,” Mach. Vision Appl. 1, 127-152 (1988).
    [CrossRef]
  7. J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1-8 (1986).
    [CrossRef]
  8. P. Z. Takacs, E. L. Church, C. J. Bresloff, and L. Assoufid, “Improvements in the accuracy and the repeatability of long trace profiler measurements,” Appl. Opt. 38, 5468-5479 (1999).
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    [CrossRef]
  13. E. Hecht, Optics (Addison-Wesley, 1987).
  14. F. Goos and H. Hänchen, “Ein neuer und fundamentaler Versuch zur Totalreflexion,” Ann. Phys. 1, 333-346 (1947).
    [CrossRef]
  15. F. Pillon, H. Gilles, S. Girard, and M. Laroche, “Goos-Hänchen and Imbert-Fedorov shifts for leaky guided modes,” J. Opt. Soc. Am. B 22, 1290-1299 (2005).
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  16. H. M. Lai and S. W. Chan, “Large and negative Goos-Hänchen shift near the Brewster dip on reflection from weakly absorbing media,” Opt. Lett. 27, 680-682 (2002).
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  17. Y. Hidaka and T. Nagayama, “Surface position detection apparatus, exposure apparatus, and exposure method,” Patent Cooperation treaty Application WO/2007/007549 (2007).

2007 (1)

J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
[CrossRef]

2006 (2)

T. Matsuyama, Y. Ohmura, and D. M. Williamson, “The lithographic lens: its history and evolution,” Proc. SPIE 6154, 615403 (2006).
[CrossRef]

Y. Tanaka, T. Watanabe, K. Hamamoto, and H. Kinoshita, “Development of nanometer resolution focus detector in vacuum for extreme ultraviolet microscope,” Jpn. J. Appl. Phys., Part 1 45, 7163-7166 (2006).
[CrossRef]

2005 (1)

2004 (1)

F. Blais, “Review of 20 years of range sensor development,” J. Electron. Imaging 13, 231-243 (2004).
[CrossRef]

2002 (1)

2000 (1)

F. Chen, G. M. Brown, and M. Song, “Overview of three-dimensional shape measurement using optical methods,” Opt. Eng. (Bellingham) 39, 10-22 (2000).
[CrossRef]

1999 (1)

1994 (1)

1993 (1)

1988 (2)

1986 (1)

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1-8 (1986).
[CrossRef]

1947 (1)

F. Goos and H. Hänchen, “Ein neuer und fundamentaler Versuch zur Totalreflexion,” Ann. Phys. 1, 333-346 (1947).
[CrossRef]

Assoufid, L.

Basila, D.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1-8 (1986).
[CrossRef]

Bennett, J. M.

Besl, P. J.

P. J. Besl, “Active, optical range imaging sensors,” Mach. Vision Appl. 1, 127-152 (1988).
[CrossRef]

Bhushan, B.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1-8 (1986).
[CrossRef]

Blais, F.

F. Blais, “Review of 20 years of range sensor development,” J. Electron. Imaging 13, 231-243 (2004).
[CrossRef]

Bresloff, C. J.

Brown, G. M.

F. Chen, G. M. Brown, and M. Song, “Overview of three-dimensional shape measurement using optical methods,” Opt. Eng. (Bellingham) 39, 10-22 (2000).
[CrossRef]

Chan, S. W.

Chen, F.

F. Chen, G. M. Brown, and M. Song, “Overview of three-dimensional shape measurement using optical methods,” Opt. Eng. (Bellingham) 39, 10-22 (2000).
[CrossRef]

Church, E. L.

Elings, V.

Fujiwara, T.

J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
[CrossRef]

Gilles, H.

Girard, S.

Goos, F.

F. Goos and H. Hänchen, “Ein neuer und fundamentaler Versuch zur Totalreflexion,” Ann. Phys. 1, 333-346 (1947).
[CrossRef]

Hamamoto, K.

Y. Tanaka, T. Watanabe, K. Hamamoto, and H. Kinoshita, “Development of nanometer resolution focus detector in vacuum for extreme ultraviolet microscope,” Jpn. J. Appl. Phys., Part 1 45, 7163-7166 (2006).
[CrossRef]

Hänchen, H.

F. Goos and H. Hänchen, “Ein neuer und fundamentaler Versuch zur Totalreflexion,” Ann. Phys. 1, 333-346 (1947).
[CrossRef]

Hecht, E.

E. Hecht, Optics (Addison-Wesley, 1987).

Hidaka, Y.

Y. Hidaka and T. Nagayama, “Surface position detection apparatus, exposure apparatus, and exposure method,” Patent Cooperation treaty Application WO/2007/007549 (2007).

Ishii, Y.

J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
[CrossRef]

Ishikawa, J.

J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
[CrossRef]

Kinoshita, H.

Y. Tanaka, T. Watanabe, K. Hamamoto, and H. Kinoshita, “Development of nanometer resolution focus detector in vacuum for extreme ultraviolet microscope,” Jpn. J. Appl. Phys., Part 1 45, 7163-7166 (2006).
[CrossRef]

Kjoller, K.

Kohno, T.

Koliopoulos, C. L.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1-8 (1986).
[CrossRef]

Lai, H. M.

Laroche, M.

Matsuyama, T.

T. Matsuyama, Y. Ohmura, and D. M. Williamson, “The lithographic lens: its history and evolution,” Proc. SPIE 6154, 615403 (2006).
[CrossRef]

Miyamoto, K.

Mizutani, H.

H. Mizutani, “Surface position detecting apparatus and method,” U.S. Patent 5,602,399 (Jan. 2, 1996).

Musha, T.

Nagayama, T.

Y. Hidaka and T. Nagayama, “Surface position detection apparatus, exposure apparatus, and exposure method,” Patent Cooperation treaty Application WO/2007/007549 (2007).

Nei, M.

J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
[CrossRef]

Ohmura, Y.

T. Matsuyama, Y. Ohmura, and D. M. Williamson, “The lithographic lens: its history and evolution,” Proc. SPIE 6154, 615403 (2006).
[CrossRef]

Ozawa, N.

Pillon, F.

Shiraishi, K.

J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
[CrossRef]

Song, M.

F. Chen, G. M. Brown, and M. Song, “Overview of three-dimensional shape measurement using optical methods,” Opt. Eng. (Bellingham) 39, 10-22 (2000).
[CrossRef]

Takacs, P. Z.

Tanaka, Y.

Y. Tanaka, T. Watanabe, K. Hamamoto, and H. Kinoshita, “Development of nanometer resolution focus detector in vacuum for extreme ultraviolet microscope,” Jpn. J. Appl. Phys., Part 1 45, 7163-7166 (2006).
[CrossRef]

Tiziani, H. J.

Uhde, H. M.

Watanabe, T.

Y. Tanaka, T. Watanabe, K. Hamamoto, and H. Kinoshita, “Development of nanometer resolution focus detector in vacuum for extreme ultraviolet microscope,” Jpn. J. Appl. Phys., Part 1 45, 7163-7166 (2006).
[CrossRef]

Williamson, D. M.

T. Matsuyama, Y. Ohmura, and D. M. Williamson, “The lithographic lens: its history and evolution,” Proc. SPIE 6154, 615403 (2006).
[CrossRef]

Wyant, J. C.

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1-8 (1986).
[CrossRef]

Ann. Phys. (1)

F. Goos and H. Hänchen, “Ein neuer und fundamentaler Versuch zur Totalreflexion,” Ann. Phys. 1, 333-346 (1947).
[CrossRef]

Appl. Opt. (4)

J. Electron. Imaging (1)

F. Blais, “Review of 20 years of range sensor development,” J. Electron. Imaging 13, 231-243 (2004).
[CrossRef]

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

J. Tribol. (1)

J. C. Wyant, C. L. Koliopoulos, B. Bhushan, and D. Basila, “Development of a three-dimensional noncontact digital optical profiler,” J. Tribol. 108, 1-8 (1986).
[CrossRef]

Jpn. J. Appl. Phys., Part 1 (1)

Y. Tanaka, T. Watanabe, K. Hamamoto, and H. Kinoshita, “Development of nanometer resolution focus detector in vacuum for extreme ultraviolet microscope,” Jpn. J. Appl. Phys., Part 1 45, 7163-7166 (2006).
[CrossRef]

Mach. Vision Appl. (1)

P. J. Besl, “Active, optical range imaging sensors,” Mach. Vision Appl. 1, 127-152 (1988).
[CrossRef]

Opt. Eng. (Bellingham) (1)

F. Chen, G. M. Brown, and M. Song, “Overview of three-dimensional shape measurement using optical methods,” Opt. Eng. (Bellingham) 39, 10-22 (2000).
[CrossRef]

Opt. Lett. (1)

Proc. SPIE (2)

J. Ishikawa, T. Fujiwara, K. Shiraishi, Y. Ishii, and M. Nei, “Latest results from the hyper-NA immersion scanners S609B and S610C,” Proc. SPIE 6520, 65201W (2007).
[CrossRef]

T. Matsuyama, Y. Ohmura, and D. M. Williamson, “The lithographic lens: its history and evolution,” Proc. SPIE 6154, 615403 (2006).
[CrossRef]

Other (3)

H. Mizutani, “Surface position detecting apparatus and method,” U.S. Patent 5,602,399 (Jan. 2, 1996).

Y. Hidaka and T. Nagayama, “Surface position detection apparatus, exposure apparatus, and exposure method,” Patent Cooperation treaty Application WO/2007/007549 (2007).

E. Hecht, Optics (Addison-Wesley, 1987).

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Figures (15)

Fig. 1
Fig. 1

Optical system configuration of the focus sensor.

Fig. 2
Fig. 2

Beam shifts according to z displacement of the wafer surface.

Fig. 3
Fig. 3

Spectral reflectance of each polarization.

Fig. 4
Fig. 4

Various types of measurement errors predicted by theoretical estimation.

Fig. 5
Fig. 5

Explanation of the error induced by inhomogeneous reflectivity.

Fig. 6
Fig. 6

Schematic diagram of the experimental setup.

Fig. 7
Fig. 7

Explanation of experimental sample A.

Fig. 8
Fig. 8

Explanation of experimental sample B.

Fig. 9
Fig. 9

Top view of the samples and the projected slit in the experiment.

Fig. 10
Fig. 10

Explanation of experiment using sample B

Fig. 11
Fig. 11

Experimental results with sample B: (a) region 1; (b) region 2; (c) region 3; (d) region 4.

Fig. 12
Fig. 12

Reduction method for thickness-dependent errors.

Fig. 13
Fig. 13

Reduction method for pattern-dependent errors.

Fig. 14
Fig. 14

Schematic description of phase plates.

Fig. 15
Fig. 15

Slit images: left, conventional method; right, proposed method.

Tables (3)

Tables Icon

Table 1 Thickness of Si O 2 on Sample A Measured with Ellipsometry and Stylus Profiler

Tables Icon

Table 2 Line Width of Every Liner Pattern on Sample B

Tables Icon

Table 3 Summary of Experimental Results with Sample A

Equations (12)

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Δ Z ( C W S ) = L S ape [ R p ( λ , θ i , C W S ) δ z p ( λ , θ i ) + R s ( λ , θ i , C W S ) δ z s ( λ , θ i ) ] d λ d θ i L S ape [ R p ( λ , θ i , C W S ) + R s ( λ , θ i , C W S ) ] d λ d θ i ,
δ z p ( λ , θ i ) = δ z s ( λ , θ i ) = d C A w L w S ( λ w L + w S 2 ) 1 2 m sin θ a ,
Δ Z ( C W S ) = d C A 2 m ( w L w S ) sin θ a w S w L ape ( R fig 3 , p + R fig 3 , s ) ( λ w L + w S 2 ) d λ d θ i w S w L ape ( R fig 3 , p + R fig 3 , s ) d λ d θ i ,
δ z p ( λ , θ i ) = δ z s ( λ , θ i ) = d S A ( θ i ) tan ( θ i θ a ) 2 m 2 sin θ a ,
Δ Z ( C W S ) = 1 2 m 2 sin θ a w S w L ape ( R fig 3 , p + R fig 3 , s ) d S A ( θ i ) tan ( θ i θ a ) d λ d θ i w S w L ape ( R fig 3 , p + R fig 3 , s ) d λ d θ i .
δ z p ( λ , θ i ) = δ z s ( λ , θ i ) = d PDS - o ( θ i ) 2 m sin θ a ,
Δ Z ( C W S ) = 1 2 m sin θ a w S w L ape ( R fig 3 , p + R fig 3 , s ) d PDS - o ( θ i ) d λ d θ i w S w L ape ( R fig 3 , p + R fig 3 , s ) d λ d θ i .
S = d Φ k d θ i ,
Δ Z ( C W S ) = d Φ 2 k sin θ i d θ i .
δ L = L a + L b 2 R a L a + R b L b 2 R a ( R a L a R b L b ) ,
= L a + L b 2 R a L a + R b L b 2 R b ( R a L a R b L b ) ,
Δ Z ( C W S ) = δ L 2 tan θ i .

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