Abstract

A derivative technique is developed for measuring the material response of photosensitive films. The method consists of recording a low modulated grating superimposed with different uniform preexposures. The modulation of the resulting shallow gratings recorded on the photosensitive film is measured by diffraction techniques and the derivative response is thus computed. Compared with other diffraction-based methods, this one is not affected by nonlinearities. Qualitative visual monitoring of these diffraction data may be used for optimizing materials and processes in photolithography and optical recording. Some experimental results concerning positive and negative photoresists are presented.

© 1985 Optical Society of America

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References

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    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  11. M. Françon, Progress in Microscopy (Row, Peterson, Elmsford, N.Y., 1961), Chap. 6.

1984 (2)

1982 (1)

1976 (1)

R. Grousson, S. Mallick, “Multiple Image Storage Using a Crossed Grating,” Nouv. Rev. Opt. 2, 77 (1976).
[CrossRef]

1974 (1)

1972 (1)

1971 (1)

1970 (1)

1969 (1)

Bartolini, R. A.

Beesley, M. J.

Castledine, J. G.

Cescato, L.

Françon, M.

M. Françon, Progress in Microscopy (Row, Peterson, Elmsford, N.Y., 1961), Chap. 6.

Frejlich, J.

Goodman, J. W.

J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, New York, 1968).

Grousson, R.

R. Grousson, S. Mallick, “Multiple Image Storage Using a Crossed Grating,” Nouv. Rev. Opt. 2, 77 (1976).
[CrossRef]

Jenney, J. A.

Johnson, L. F.

Lin, L. H.

Mallick, S.

R. Grousson, S. Mallick, “Multiple Image Storage Using a Crossed Grating,” Nouv. Rev. Opt. 2, 77 (1976).
[CrossRef]

Meier, R. W.

Mendes, G. F.

Urbach, J. C.

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Figures (4)

Fig. 1
Fig. 1

Derivative technique schema. A low-modulated (ΔE) lamellar pattern of light of period 1/f and average energy E is projected on a photoresist thin film having a material response curve (h vs E) as represented. After exposure and developing a lamellar grating results of period 1/f, thickness modulation Δh, and average thickness h. The quantity ΔhE represents the response curve derivative.

Fig. 2
Fig. 2

Derivative response curves for AZ-1350B photoresist. Experimentally measured derivatives and their computed integral curves are shown for a film coated using a spinner at 1000 rpm and developed with NaOH 1.06-N water solution diluted (A) 1:8 and (B) 1:14. The same curves are shown for another film coated at 4000 rpm and developed with the same NaOH solution diluted (C) 1:8 and (D) 1:14. The derivative and etched thicknesses are represented on the ordinate on the left- and right-hand sides, respectively; h represents the remaining film thickness. The reported initial film thickness h0 was measured by interferential microscopy as described in the text, with an estimated ±150-Å uncertainty.

Fig. 3
Fig. 3

Response curve for KMR-747 negative resist. The derivative curve is shown as measured for a film coated with a spinner at 4000 rpm (A). The integral response curves were independently measured by recording full modulated lamellar gratings and measuring their diffraction spectra (B).

Fig. 4
Fig. 4

Normalized response curves. The curves appearing in Figs. 2 and 3 are now normalized on their respective h0 and represented here for comparison.

Equations (2)

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β = g ( E ) ,
η = J 1 2 ( ϕ / 2 ) with ϕ 2 π ( n 1 ) h / λ ,

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