Abstract

Measurement and control of high-aspect-ratio structures such as dynamic random-access memory trenches is an important step in the manufacture of modern memory devices. We present a novel technique based on infrared interferometry that has been implemented in manufacturing and is capable of measuring sub- 0.25µm-wide and 10µm-deep trenches nondestructively and with an accuracy of better than 0.1 µm.

© 1999 Optical Society of America

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References

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  1. G. S. Kino, J. Vac. Sci. Technol. B 8, 1652 (1990).
    [Crossref]
  2. F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
    [Crossref]
  3. T. R. Corle and G. S. Kino, Confocal Scanning Optical Microscopy and Related Techniques (Academic, San Diego, Calif., 1996).
  4. F. C. Chang and G. S. Kino, Appl. Opt. 37, 3471 (1998).
    [Crossref]
  5. N. Balasubramanian, “Optical system for surface topography measurement,” U.S. patent4,340,306 (July20, 1982).
  6. P. de Groot and L. Deck, Opt. Lett. 18, 1462 (1993).
    [Crossref] [PubMed]
  7. H. K. Wickramasinghe, “Method for measuring a trench depth parameter of a material,” U.S. patent5,392,118 (February21, 1995).

1998 (1)

1993 (2)

F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
[Crossref]

P. de Groot and L. Deck, Opt. Lett. 18, 1462 (1993).
[Crossref] [PubMed]

1990 (1)

G. S. Kino, J. Vac. Sci. Technol. B 8, 1652 (1990).
[Crossref]

Balasubramanian, N.

N. Balasubramanian, “Optical system for surface topography measurement,” U.S. patent4,340,306 (July20, 1982).

Chang, F. C.

F. C. Chang and G. S. Kino, Appl. Opt. 37, 3471 (1998).
[Crossref]

F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
[Crossref]

Chim, S. S. C.

F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
[Crossref]

Chou, C.-H.

F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
[Crossref]

Corle, T. R.

T. R. Corle and G. S. Kino, Confocal Scanning Optical Microscopy and Related Techniques (Academic, San Diego, Calif., 1996).

de Groot, P.

Deck, L.

Kino, G. S.

F. C. Chang and G. S. Kino, Appl. Opt. 37, 3471 (1998).
[Crossref]

F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
[Crossref]

G. S. Kino, J. Vac. Sci. Technol. B 8, 1652 (1990).
[Crossref]

T. R. Corle and G. S. Kino, Confocal Scanning Optical Microscopy and Related Techniques (Academic, San Diego, Calif., 1996).

Studenmund, W. R.

F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
[Crossref]

Wickramasinghe, H. K.

H. K. Wickramasinghe, “Method for measuring a trench depth parameter of a material,” U.S. patent5,392,118 (February21, 1995).

Appl. Opt. (1)

J. Vac. Sci. Technol. B (1)

G. S. Kino, J. Vac. Sci. Technol. B 8, 1652 (1990).
[Crossref]

Opt. Lett. (1)

Proc. SPIE (1)

F. C. Chang, G. S. Kino, W. R. Studenmund, S. S. C. Chim, and C.-H. Chou, Proc. SPIE 1926, 464 (1993).
[Crossref]

Other (3)

T. R. Corle and G. S. Kino, Confocal Scanning Optical Microscopy and Related Techniques (Academic, San Diego, Calif., 1996).

N. Balasubramanian, “Optical system for surface topography measurement,” U.S. patent4,340,306 (July20, 1982).

H. K. Wickramasinghe, “Method for measuring a trench depth parameter of a material,” U.S. patent5,392,118 (February21, 1995).

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Figures (5)

Fig. 1
Fig. 1

Typical SEM cross section of a DRAM trench.

Fig. 2
Fig. 2

Scheme for infrared interferometric measurement of trench depth.

Fig. 3
Fig. 3

Typical interference output versus wavelength obtained for an 8µm-deep, 0.25µm-wide trench array in silicon; the trench depth is derived from the distance between maxima in the curves.

Fig. 4
Fig. 4

Comparison of cross-section measurements and infrared interference measurements of trench depths for several samples.

Fig. 5
Fig. 5

Map of trench depth variation across an entire DRAM wafer for 0.25µm-wide trenches with a nominal depth of 8 µm.

Equations (3)

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Ef=RfEi expjϕf,
Eb=RbEi expj2knd,
I=Rf2Ei2+Rb2Ei2+2RfRb cos2knd-ϕf.

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