Abstract

For quality control in high volume manufacturing of thin layers and for tracking of physical and chemical processes, ellipsometry is a common measurement technology. For such kinds of applications we present a novel approach of fast ellipsometric measurements. Instead of a conventional setup that uses a standard photo-elastic modulator, we use a 92 kHz Single Crystal Photo-Elastic Modulator (SCPEM), which is a LiTaO3 crystal with a size of 28 × 9 × 4 mm. This small, simple, and cost-effective solution also offers the advantage of direct control of the retardation via the current amplitude, which is important for repeatability of the measurements. Instead of a Lock-In Amplifier, an automated digital processing based on a fast analog to digital converter controlled by a highly flexible Field Programmable Gate Array is used. This and the extremely compact and efficient polarization modulation allow fast ellipsometric testing where the upper limit of measurement rates is mainly limited by the desired accuracy and repeatability of the measurements. The standard deviation that is related to the repeatability +/–0.002° for dielectric layers can be easily reached.

© 2010 OSA

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References

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  1. H. G. Tompkins, A Users's Guide to Ellipsometry, Academic Press Inc., London (1993).
  2. B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
    [CrossRef]
  3. Product bulletin, http://www.hindsinstruments.com/wp-content/uploads/Abrio-Product-Bulletin.pdf
  4. C.-Y. Han and Y.-F. Chao, “Photoelastic modulated imaging ellipsometry by stroboscopic illumination technique,” Rev. Sci. Instrum. 77(2), 023107 (2006).
    [CrossRef]
  5. M. V. Khazimullin and Y. A. Lebedev, “Fourier transform approach in modulation technique of experimental measurements,” Rev. Sci. Instrum. 81(4), 043110 (2010).
    [CrossRef] [PubMed]
  6. J. C. Kemp, “Piezo-optical birefringence modulators: new use for a long-known effect,” J. Opt. Soc. Am. 59, 950–954 (1969).
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  8. A. Zeng, L. Huang, Z. Dong, J. Hu, H. Huang, and X. Wang, “Calibration method for a photoelastic modulator with a peak retardation of less than a half-wavelength,” Appl. Opt. 46(5), 699–703 (2007).
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  9. F. Bammer, B. Holzinger, and T. Schumi, “A single crystal photo-elastic modulator,” Proc. SPIE 6469, 1–8 (2007).
  10. S.-M. F. Nee, “Error analysis of null ellipsometry with depolarization,” Appl. Opt. 38(25), 5388–5398 (1999).
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  11. H. Zhu, L. Liu, Y. Wen, Z. Lü, and B. Zhang, “High-precision system for automatic null ellipsometric measurement,” Appl. Opt. 41(22), 4536–4540 (2002).
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  12. S. N. Jasperson and S. E. Schnatterly, “An improved method for high reflectivity ellipsometry based on a new polarization modulation technique,” Rev. Sci. Instrum. 40(6), 761–767 (1969).
    [CrossRef]
  13. R. Petkovsek, F. Bammer, D. Schuöcker, and J. Mozina, “Dual-mode single-crystal photo-elastic modulator and possible applications,” Appl. Opt. 48(7), C86–C91 (2009).
    [CrossRef] [PubMed]
  14. K. Postava, A. Maziewski, T. Yamaguchi, R. Ossikovski, S. Višnovsky, and J. Pištora, “Null ellipsometer with phase modulation,” Opt. Express 12(24), 6040–6045 (2004), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-12-24-6040 .
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2010 (1)

M. V. Khazimullin and Y. A. Lebedev, “Fourier transform approach in modulation technique of experimental measurements,” Rev. Sci. Instrum. 81(4), 043110 (2010).
[CrossRef] [PubMed]

2009 (1)

2007 (2)

2006 (1)

C.-Y. Han and Y.-F. Chao, “Photoelastic modulated imaging ellipsometry by stroboscopic illumination technique,” Rev. Sci. Instrum. 77(2), 023107 (2006).
[CrossRef]

2004 (1)

2002 (1)

1999 (1)

1983 (1)

1982 (1)

B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
[CrossRef]

1969 (2)

S. N. Jasperson and S. E. Schnatterly, “An improved method for high reflectivity ellipsometry based on a new polarization modulation technique,” Rev. Sci. Instrum. 40(6), 761–767 (1969).
[CrossRef]

J. C. Kemp, “Piezo-optical birefringence modulators: new use for a long-known effect,” J. Opt. Soc. Am. 59, 950–954 (1969).

Badoz, J.

Bammer, F.

Canit, J. C.

Chao, Y.-F.

C.-Y. Han and Y.-F. Chao, “Photoelastic modulated imaging ellipsometry by stroboscopic illumination technique,” Rev. Sci. Instrum. 77(2), 023107 (2006).
[CrossRef]

Dalby, J. L.

B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
[CrossRef]

Dong, Z.

Drévillon, B.

B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
[CrossRef]

Han, C.-Y.

C.-Y. Han and Y.-F. Chao, “Photoelastic modulated imaging ellipsometry by stroboscopic illumination technique,” Rev. Sci. Instrum. 77(2), 023107 (2006).
[CrossRef]

Holzinger, B.

F. Bammer, B. Holzinger, and T. Schumi, “A single crystal photo-elastic modulator,” Proc. SPIE 6469, 1–8 (2007).

Hu, J.

Huang, H.

Huang, L.

Jasperson, S. N.

S. N. Jasperson and S. E. Schnatterly, “An improved method for high reflectivity ellipsometry based on a new polarization modulation technique,” Rev. Sci. Instrum. 40(6), 761–767 (1969).
[CrossRef]

Kemp, J. C.

Khazimullin, M. V.

M. V. Khazimullin and Y. A. Lebedev, “Fourier transform approach in modulation technique of experimental measurements,” Rev. Sci. Instrum. 81(4), 043110 (2010).
[CrossRef] [PubMed]

Lebedev, Y. A.

M. V. Khazimullin and Y. A. Lebedev, “Fourier transform approach in modulation technique of experimental measurements,” Rev. Sci. Instrum. 81(4), 043110 (2010).
[CrossRef] [PubMed]

Liu, L.

Lü, Z.

Marbot, R.

B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
[CrossRef]

Maziewski, A.

Mozina, J.

Nee, S.-M. F.

Ossikovski, R.

Perrin, J.

B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
[CrossRef]

Petkovsek, R.

Pištora, J.

Postava, K.

Schnatterly, S. E.

S. N. Jasperson and S. E. Schnatterly, “An improved method for high reflectivity ellipsometry based on a new polarization modulation technique,” Rev. Sci. Instrum. 40(6), 761–767 (1969).
[CrossRef]

Schumi, T.

F. Bammer, B. Holzinger, and T. Schumi, “A single crystal photo-elastic modulator,” Proc. SPIE 6469, 1–8 (2007).

Schuöcker, D.

Violet, A.

B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
[CrossRef]

Višnovsky, S.

Wang, X.

Wen, Y.

Yamaguchi, T.

Zeng, A.

Zhang, B.

Zhu, H.

Appl. Opt. (5)

J. Opt. Soc. Am. (1)

Opt. Express (1)

Proc. SPIE (1)

F. Bammer, B. Holzinger, and T. Schumi, “A single crystal photo-elastic modulator,” Proc. SPIE 6469, 1–8 (2007).

Rev. Sci. Instrum. (4)

S. N. Jasperson and S. E. Schnatterly, “An improved method for high reflectivity ellipsometry based on a new polarization modulation technique,” Rev. Sci. Instrum. 40(6), 761–767 (1969).
[CrossRef]

B. Drévillon, J. Perrin, R. Marbot, A. Violet, and J. L. Dalby, “Fast polarization modulated ellipsometer using a microprocessor system for digital Fourier analysis,” Rev. Sci. Instrum. 53(7), 969–977 (1982).
[CrossRef]

C.-Y. Han and Y.-F. Chao, “Photoelastic modulated imaging ellipsometry by stroboscopic illumination technique,” Rev. Sci. Instrum. 77(2), 023107 (2006).
[CrossRef]

M. V. Khazimullin and Y. A. Lebedev, “Fourier transform approach in modulation technique of experimental measurements,” Rev. Sci. Instrum. 81(4), 043110 (2010).
[CrossRef] [PubMed]

Other (2)

Product bulletin, http://www.hindsinstruments.com/wp-content/uploads/Abrio-Product-Bulletin.pdf

H. G. Tompkins, A Users's Guide to Ellipsometry, Academic Press Inc., London (1993).

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Figures (7)

Fig. 1
Fig. 1

Schematic diagram of a PEM-based ellipsometer

Fig. 2
Fig. 2

Influence of initial retardation inaccuracy (a) and inaccuracy of I 1/I 2 (b); measurement on absolute deviation of ellipsometric angle Δ.

Fig. 3
Fig. 3

Influence of initial retardation inaccuracy (a) and inaccuracy of I 1/I 0 (b) as well I 2/I 0 (c); measurement on absolute deviation of ellipsometric angle ψ.

Fig. 4
Fig. 4

Relation between SCPEM retardation amplitude and amplitude of the driving current.

Fig. 5
Fig. 5

Schematic diagram of driver and measuring unit

Fig. 6
Fig. 6

Typical waveform corresponding to reflection from: dielectric surfaces: sapphire and glass (upper two graphs); metal surfaces: stainless steel and copper (lower two graphs). Vertical axes represent amplitude normalized to 1.

Fig. 7
Fig. 7

Typical repeatability of ellipsometric angles measurement for dielectric surfaces (glass, sapphire) for acquisition times of 0.3 ms and 20 ms (in degrees).

Tables (2)

Tables Icon

Table 1 Influence of acquisition time on repeatability of results for Δ obtained from measurement for different dielectric and metallic surfaces. In general a longer acquisition time corresponds to a lower standard deviation and therefore to better repeatability of the results.

Tables Icon

Table 2 Results obtained from measurement of ellipsometric angles for different dielectric and metallic surfaces. The acquisition time for one single measurement was 20 ms.

Equations (9)

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δ = δ 0 + δ 1 sin Ω t
tan ψ = | R p | / | R s | ,     Δ = arg R p arg R s ,
T = ( 1 + tan 2 ψ + 2 tan ψ cos ( Δ S + δ 1 sin ω t ) ) / 4
I 1 I 0 = 4 J 1 ( δ 1 )sin Δ S tanψ 1+ tan 2 ψ2 J 0 ( δ 1 )tanψcos Δ S I 2 I 0 = 4 J 2 ( δ 1 )sin Δ S tanψ 1+ tan 2 ψ2 J 0 ( δ 1 )tanψcos Δ S I 1 I 2 = J 1 ( δ 1 ) J 2 ( δ 1 ) tan  Δ S
I 1 I 0 = 4 J 1 ( δ B ) sin Δ S tan ψ 1 + tan 2 ψ , I 2 I 0 = 4 J 2 ( δ B ) cos Δ S tan ψ 1 + tan 2 ψ
I ˜ = ( 1 J 1 ( δ B ) I 1 I 0 ) 2 + ( 1 J 2 ( δ B ) I 2 I 0 ) 2 = 4 tan ψ 1 + tan 2 ψ
tan ψ = 2 ± 4 I ˜ 2 I ˜ ,     tan Δ S = J 2 ( δ 1 ) I 1 J 1 ( δ 1 ) I 2
I 0 ( δ 1 ) I 0 ( 0 ) = 1 + J 0 ( δ 1 ) 2
δ 1 i 1 c o n s t     for     f R f FWHM 2 < f < f R + f FWHM 2

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