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Probing Pore Characteristics in Low-K Thin Films Using Positronium Annihilation Lifetime Spectroscopy

Published online by Cambridge University Press:  17 March 2011

D. W. Gidley ,
W. E. Frieze ,
T. L. Dull ,
J. N. Sun  and
A. F. Yee
D. W. Gidley
Affiliation:
Department of Physics, University of Michigan, Ann Arbor, MI 48109
W. E. Frieze
Affiliation:
Department of Physics, University of Michigan, Ann Arbor, MI 48109
T. L. Dull
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109
J. N. Sun
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109
A. F. Yee
Affiliation:
Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109
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Abstract

Depth profiled positronium annihilation lifetime spectroscopy (PALS) has been used to probe the pore characteristics (size, distribution, and interconnectivity) in thin, porous films, including silica and organic-based films. The technique is sensitive to all pores (both interconnected and closed) in the size range from 0.3 nm to 300 nm, even in films buried under a diffusion barrier. PALS may be particularly useful in deducing the pore-size distribution in closed-pore systems where gas absorption methods are not available. In this technique a focussed beam of several keV positrons forms positronium (Ps, the electron-positron bound state) with a depth distribution that depends on the selected positron beam energy. Ps inherently localizes in the pores where its natural (vacuum) annihilation lifetime of 142 ns is reduced by collisions with the pore surfaces. The collisionally reduced Ps lifetime is correlated with pore size and is the key feature in transforming a Ps lifetime distribution into a pore size distribution. In thin silica films that have been made porous by a variety of methods the pores are found to be interconnected and an average pore size is determined. In a mesoporous methyl-silsesquioxane film with nominally closed pores a pore size distribution has been determined. The sensitivity of PALS to metal overlayer interdiffusion is demonstrated. PALS is a non-destructive, depth profiling technique with the only requirement that positrons can be implanted into the porous film where Ps can form.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 612: Symposium D – Materials, Technology & Reliability for Advanced Interconnects.. , 2000 , D4.3.1
Copyright
Copyright © Materials Research Society 2000

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References

1. Wu, W.-L., Wallace, W. E., Lin, E. K., Lynn, G. W., Glinka, C. J., Ryan, E. T. and Ho, H.-M., Appl. Phys. 87, 1193 (2000).10.1063/1.371997Google Scholar
2. 2.Gidley, D. W., Frieze, W. E., Yee, A. F., Dull, T. L., Ryan, E. T., and Ho, H.-M., Phys. Rev. B. 60 (Rapid Comm.), R5157 (1999).Google Scholar
3. Petkov, M. P., Weber, M. H., Lynn, K. G., Rodbell, K. P., and Cohen, S. A., J. Appl. Phys. 86, 3104 (1999).10.1063/1.371174Google Scholar
4. Gidley, D. W., Frieze, W. E., Dull, T. L., Sun, J., Yee, A. F., Nguyen, C. V., and Yoon, D. Y., Appl. Phys. Lett. 76, 1282 (2000).10.1063/1.126009Google Scholar
5. Gidley, D. W., Marko, K. A., and Rich, A., Phys. Rev. Lett. 36, 395 (1976).10.1103/PhysRevLett.36.395Google Scholar
6. Tao, S. J., J. Chem. Phys. 56, 5499 (1972).10.1063/1.1677067Google Scholar
7. Eldrup, M., Lighbody, D., and Sherwood, J. N., Chem. Phys. 63, 51 (1981).10.1016/0301-0104(81)80307-2Google Scholar
8. Wang, Y. Y., Nakanishi, Y., Jean, Y. C., and Sandreczki, T. C., J. Polym. Sci., Part B: Polym. Phys. 28, 1431 (1990).10.1002/polb.1990.090280902Google Scholar
9. Ito, K., Nakanishi, H., and Ujihira, Y., J. Phys. Chem. B 103, 4555 (1999) and references therein.10.1021/jp9831841Google Scholar
10. Provencher, S. W., Comput. Phys. Commun. 27, 213 (1982).10.1016/0010-4655(82)90173-4Google Scholar