Abstract

We have extended the use of a dispersive white-light interferometer for absolute distance measurement to include effects of dielectric multilayer systems on the target. The phase of the reflected wave changes as a function of wavelength and layer thickness and causes errors in the interferometric distance measurement. With dispersive white-light interferometry these effects can be measured in situ, and the correct mechanical distance can be determined. The effects of thin films deposited upon the target have been investigated for one and two layers (photoresist and SiO2 upon Si). Experimental results show that the thicknesses of these layers can also be determined with an accuracy of the order of 10 nm.

© 1996 Optical Society of America

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References

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1995 (2)

U. Schnell, E. Zimmermann, R. Dändliker, Pure Appl. Opt. 4, 643 (1995).
[CrossRef]

C. L. Mitsas, D. I. Siapkas, Appl. Opt. 34, 1678 (1995).
[CrossRef] [PubMed]

1994 (1)

1992 (1)

1990 (1)

1989 (1)

J. Mannhardt, T. Fuchs, M. Mächler, Feinwerk-technik & Messtechnik 97, 269 (1989).

1987 (1)

M. Davidson, K. Kaufman, K. Mazor, F. Cohen, Proc. SPIE 775, 233–247 (1987).

1985 (1)

K.-P. Koch, M. Maechler, F. Glueck, Rev. Sci. Instrum. 56, 2243 (1985).
[CrossRef]

1983 (1)

1973 (1)

Azzam, R. M. A.

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light (North-Holland, Amsterdam, 1987), pp. 153–416.

Bashara, N. M.

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light (North-Holland, Amsterdam, 1987), pp. 153–416.

Cohen, F.

M. Davidson, K. Kaufman, K. Mazor, F. Cohen, Proc. SPIE 775, 233–247 (1987).

Dändliker, R.

U. Schnell, E. Zimmermann, R. Dändliker, Pure Appl. Opt. 4, 643 (1995).
[CrossRef]

Davidson, M.

M. Davidson, K. Kaufman, K. Mazor, F. Cohen, Proc. SPIE 775, 233–247 (1987).

Dobrowolski, J. A.

Fuchs, T.

J. Mannhardt, T. Fuchs, M. Mächler, Feinwerk-technik & Messtechnik 97, 269 (1989).

Glueck, F.

K.-P. Koch, M. Maechler, F. Glueck, Rev. Sci. Instrum. 56, 2243 (1985).
[CrossRef]

Ho, F. C.

Kaufman, K.

M. Davidson, K. Kaufman, K. Mazor, F. Cohen, Proc. SPIE 775, 233–247 (1987).

Koch, K.-P.

K.-P. Koch, M. Maechler, F. Glueck, Rev. Sci. Instrum. 56, 2243 (1985).
[CrossRef]

Mächler, M.

J. Mannhardt, T. Fuchs, M. Mächler, Feinwerk-technik & Messtechnik 97, 269 (1989).

Maechler, M.

K.-P. Koch, M. Maechler, F. Glueck, Rev. Sci. Instrum. 56, 2243 (1985).
[CrossRef]

Mannhardt, J.

J. Mannhardt, T. Fuchs, M. Mächler, Feinwerk-technik & Messtechnik 97, 269 (1989).

Mazor, K.

M. Davidson, K. Kaufman, K. Mazor, F. Cohen, Proc. SPIE 775, 233–247 (1987).

Merklein, T. M.

Mitsas, C. L.

Polhemus, C.

Schnell, U.

U. Schnell, E. Zimmermann, R. Dändliker, Pure Appl. Opt. 4, 643 (1995).
[CrossRef]

Schwider, J.

Siapkas, D. I.

Waldorf, A.

Zhou, L.

Zimmermann, E.

U. Schnell, E. Zimmermann, R. Dändliker, Pure Appl. Opt. 4, 643 (1995).
[CrossRef]

Appl. Opt. (5)

Feinwerk-technik & Messtechnik (1)

J. Mannhardt, T. Fuchs, M. Mächler, Feinwerk-technik & Messtechnik 97, 269 (1989).

Opt. Lett. (1)

Proc. SPIE (1)

M. Davidson, K. Kaufman, K. Mazor, F. Cohen, Proc. SPIE 775, 233–247 (1987).

Pure Appl. Opt. (1)

U. Schnell, E. Zimmermann, R. Dändliker, Pure Appl. Opt. 4, 643 (1995).
[CrossRef]

Rev. Sci. Instrum. (1)

K.-P. Koch, M. Maechler, F. Glueck, Rev. Sci. Instrum. 56, 2243 (1985).
[CrossRef]

Other (2)

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light (North-Holland, Amsterdam, 1987), pp. 153–416.

Levenberg–Marquardt algorithm implemented in the MATLAB function leastsq, in Optimization Toolbox for Use with MATLAB (MathWorks, Natick, Mass., 1994).

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Figures (3)

Fig. 1
Fig. 1

Dispersive white-light interferometer to measure the absolute distance L between two surfaces with a dielectric multilayer system (MLS) on the object target: WLS, white-light source; BS, beam splitter.

Fig. 2
Fig. 2

Processing of the channeled spectrum: the observed interference signal s(ν) in the spectrum is synchronously detected with four samples per fringe period to calculate the fringe phases Φn. The variation of the average level of s(ν) is due to the change of |R| in Eq. (2) as a function of ν.

Fig. 3
Fig. 3

(a) Comparison of measured and calculated nonlinear phase contribution fnl versus optical frequency ν (wavelength λ) for photoresist (dr) upon a Si substrate. (b) Comparison of measured and calculated nonlinear phase contribution fnl versus optical frequency ν (wavelength λ) for photoresist (dr ) upon SiO2 (dSiO2 ) upon a Si substrate.

Tables (1)

Tables Icon

Table 1 Comparison of Mechanical and Optical Measurements of Layer Thickness (dr, Photoresist; dSiO2, SiO2) and Measured Distance L without (Luc) and with Correction (Lc) for Effects of the Thin Layers (ΔL = Luc − Lc)a

Equations (7)

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Φ ( ν ) = ( 2 π / c ) 2 L ν + δ r ( ν ; d m , n m ) ,
R = S 21 / S 11 = R exp ( i δ r ) ,
δ r ( ν ) = 2 π c ( m = 1 M 2 d m n m ) ν + f n l ( ν ; d m , n m ) ,
s ( ν ) = A ( ν ) + B ( ν ) cos  Φ ( ν ) ,
Δ Φ s = Φ n - Φ n - 1 4 π c L Δ ν .
S n = s n - 1 - s n + 2 = 2 B sin Δ Φ s sin  Φ n , C n = s n - s n + 2 + s n - 1 2 = 2 B sin 2 Δ Φ s cos  Φ n , Φ n = tan - 1 [ S n / C n sin  Δ Φ s ] ,
χ 2 = n = 1 N [ Φ n ( ν ) - Φ ( ν ; L , d m ) ] 2 .

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