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Study of copper-refractory metal interfaces via solid-state wetting for emerging nanoscale interconnect applications

Published online by Cambridge University Press:  01 January 2006

Oscar van der Straten ,
Yu Zhu ,
Jonathan Rullan ,
Kathleen Dunn  and
Alain E. Kaloyeros
Oscar van der Straten
Affiliation:
College of Nanoscale Science and Engineering, The University at Albany—State University of New York, Albany, New York 12203
Yu Zhu
Affiliation:
College of Nanoscale Science and Engineering, The University at Albany—State University of New York, Albany, New York 12203
Jonathan Rullan
Affiliation:
College of Nanoscale Science and Engineering, The University at Albany—State University of New York, Albany, New York 12203
Kathleen Dunn
Affiliation:
College of Nanoscale Science and Engineering, The University at Albany—State University of New York, Albany, New York 12203
Alain E. Kaloyeros*
Affiliation:
College of Nanoscale Science and Engineering, The University at Albany—State University of New York, Albany, New York 12203
*
a)Address all correspondence to this author. e-mail: AKaloyeros@uamail.albany.edu
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Abstract

Solid-state wetting experiments were carried out to derive the work of adhesion (adhesion energy) of pertinent Cu/liner interfaces via the Young–Dupré equation using contact-angle measurements of the Cu equilibrium crystal shape on Ta and TaNx liners. Four types of liner surfaces were examined: untreated sputtered Ta (uSp-Ta), untreated sputtered TaNx (uSp-TaN), untreated atomic layer deposited (ALD) TaNx (uALD-TaN), and indium surfactant-treated ALD TaNx (tALD-TaN). All Cu-liner stacks were subsequently annealed at 600 °C for 48 h in a forming gas (95% Ar/5% H2) ambient. For Cu/uSp-Ta, the work of adhesion was found to be 2170 mJ/m2, corresponding to an average contact angle of 74°, while for Cu/uSp-TaN, the work of adhesion amounted to 1850 mJ/m2 for an average contact angle of 85°. Alternatively, the work of adhesion for Cu/uALD-TaN was determined to be 1850 mJ/m2, corresponding to an average contact angle of 85°, while for Cu/tALD-TaN, the work of adhesion was 2280 mJ/m2, at an average contact angle of 70°. These findings indicate that the highest degree of surface wetting occurs for the indium surfactant-treated ALD TaNx. It is thus suggested that surfactant treatment causes a reduction in the energy barrier to Cu nucleation, resulting in an enhancement in Cu wetting characteristics and a more uniform concentration of Cu nucleation sites. A critical potential outcome is the formation of atomically smooth Cu-liner interfaces with enhanced adhesion characteristics.

Keywords

Cluster assemblyScanning electron microscopy (SEM)Transmission electron microscopy (TEM)
Type
Articles
Information
Journal of Materials Research , Volume 21 , Issue 1 , January 2006 , pp. 255 - 262
Copyright
Copyright © Materials Research Society 2006

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References

REFERENCES

1.Tesanović, Z. and Jarić, M.V.: Quantum transport and surface scattering. Phys. Rev. Lett. 57, 2760 (1986).CrossRefGoogle Scholar
2.Trivedi, N. and Ashcroft, N.W.: Quantum-size effects in transport properties of metallic films. Phys. Rev. B 38, 12298 (1988).CrossRefGoogle ScholarPubMed
3.Kaloyeros, A.E., Eisenbraun, E.T., Welch, J. and Geer, R.E.: Exploiting nanotechnology for terahertz interconnects. Semicond. Int. 26, 56 (2003).Google Scholar
4.Davis, J.A., Venkatesan, R., Kaloyeros, A., Belyansky, M., Souri, S.J., Banerjee, K., Saraswat, K.C., Rahman, A., Reif, R. and Meindl, J.D.: Interconnect limits on gigascale integration (GSI) in the 21st century. Proc. of the IEEE 89, 305 (2001).CrossRefGoogle Scholar
5.Rossnagel, S.M. and Kuan, T.S.: Alteration of Cu conductivity in the size effect regime. J. Vac. Sci. Technol. B 22, 240 (2004).CrossRefGoogle Scholar
6.Murarka, S.P., Verner, I.V. and Gutmann, R.J.: Copper—Fundamental Mechanisms for Microelectronic Applications (John Wiley & Sons, New York, 2000).Google Scholar
7.Kaloyeros, A.E. and Eisenbraun, E.: Ultrathin diffusion barriers/liners for gigascale copper metallization. Annu. Rev. Mater. Sci. 30, 363 (2000).CrossRefGoogle Scholar
8.Peters, L.: Making a better copper barrier. Semicond. Int. 26, 50 (2003).Google Scholar
9.Wynblatt, P.: The effects of interfacial segregation on wetting in solid metal-on-metal and metal-on-ceramic systems. Acta Mater. 48, 4439 (2000).CrossRefGoogle Scholar
10.Murr, L.E.: Measurement of interfacial energy and energy of adhesion by scanning electron microscopy. Mater. Sci. Eng. 12, 277 (1973).CrossRefGoogle Scholar
11.Murr, L.E.: Interfacial energetics in the TD-nickel and TD-nichrome systems. J. Mater. Sci. 9, 1309 (1974).CrossRefGoogle Scholar
12.Murr, L.E.: Interfacial Phenomena in Metals and Alloys (Addison-Wesley, Reading, MA, 1975), p. 3.Google Scholar
13.Murr, L.E. Techniques for measuring adhesive energies in metal/ceramic systems, in Adhesion Measurement of Thin Films, Thick Films, and Bulk Coatings, edited by Mittal, K.L. (ASTM STP 640 West Conshohocken, PA, 1978), pp. 82–98.CrossRefGoogle Scholar
14.Hondros, E.D.: Interfacial energies and composition in solids, in Precipitation Processes in Solids, Proceedings 1976 TMS Fall Meeting, edited by Russell, K.C. and Aaronson, H.I. (The Metallurgical Society of AIME, New York, 1978), p. 237.Google Scholar
15.Hondros, E.D.: Bonding of metal/ceramic interfaces, in Science of Hard Materials, (Inst. Phys. Conf. Ser. 75 Adam Hilger Ltd., Bristol and Boston, 1984), Chap. 2, p. 121.Google Scholar
16.Eustathopoulos, N., Nicholas, M.G. and Drevet, B.: Wettability at High Temperatures, Pergamon Materials Series, edited by Cahn, R.W. (Kidlington, Oxford, U.K., 1999), pp. 126–130.Google Scholar
17.Sundquist, B.E.: A direct determination of the anisotropy of the surface free energy of solid gold, silver, copper, nickel, and alpha and gamma iron. Acta Metall. 12, 67 (1964).CrossRefGoogle Scholar
18.Winterbottom, W.L.: Equilibrium shape of a small particle in contact with a foreign substrate. Acta Metall. 15, 303 (1967).CrossRefGoogle Scholar
19.Goodhew, P.J. and Smith, D.A.: On surface energy measurement from the shape of small crystals. Scripta Metall. 16, 69 (1982).CrossRefGoogle Scholar
20.Drechsler, M. On the equilibrium shape of metal crystals, in Surface Mobilities on Solid Materials: Fundamental Concepts and Applications, Proceedings of a NATO Advanced Study Institute, Series B: Physics, Vol. 86, edited by Binh, V.T. (Plenum Press, New York, 1983), pp. 405–457.CrossRefGoogle Scholar
21.Chatain, D., Ghetta, V. and Wynblatt, P.: Equilibrium shape of copper crystals grown on sapphire. Interface Sci. 12, 7 (2004).CrossRefGoogle Scholar
22.Desjonquères, M.C. and Spanjaard, D.: Concepts in Surface Physics, Springer Series in Surface Sciences, Vol. 30, edited by Ertl, G., Gomer, R., and Mills, D.L. (Springer-Verlag, New York (1993), pp. 230–234.Google Scholar
23.Bechstedt, F.: Principles of Surface Physics (Springer-Verlag, Berlin, Heidelberg, New York, 2003), pp. 45–63.CrossRefGoogle Scholar
24.Herring, C.: Some theorems on the free energies of crystal surfaces. Phys. Rev. 82, 87 (1951).CrossRefGoogle Scholar
25.Hondros, E.D. The measurement of liquid-vapor and solid-vapor surface energies, in Techniques of Metals Research Vol. IV: Physicochemical Measurements in Metals Research, Part 2, edited by Rapp, R.A. (Interscience Publishers, New York, 1970), pp. 293–348.Google Scholar
26.Foiles, S.M., Baskes, M.I. and Daw, M.S.: Embedded-atom-method functions for the fcc metals Cu, Ag, Au, Ni, Pd, Pt and their alloys. Phys. Rev. B 33, 7983 (1986).CrossRefGoogle ScholarPubMed
27.Vitos, L., Ruban, A.V., Skriver, H.L. and Kollár, J.: The surface energy of metals. Surf. Sci. 411, 186 (1998).CrossRefGoogle Scholar
28.Appelbaum, J.A. and Hamann, D.R.: Electronic structure of the Cu(111) surface. Solid State Comm. 27, 881 (1978).CrossRefGoogle Scholar
29.Gay, J.G., Smith, J.R., Richter, R., Arlinghaus, F.J. and Wagoner, R.H.: Surface energies in d-band metals. J. Vac. Sci. Technol. A 2, 931 (1984).CrossRefGoogle Scholar
30.Howe, J.M.: Interfaces in Materials (Wiley-Interscience, New York, 1997), p. 176.Google Scholar
31.Somorjai, G.A.: Chemistry in Two Dimensions: Surfaces (Cornell University Press, Ithaca, New York, 1981), p. 31.Google Scholar
32.Pilliar, R.M. and Nutting, J.: Solid-solid interfacial energy determinations in metal-ceramic systems. Philos. Mag. 16, 181 (1967).CrossRefGoogle Scholar
33.Gutowski, W. Thermodynamics of adhesion, in Fundamentals of Adhesion, edited by Lee, L-H. (Plenum Press, New York, 1991), Chap. 2, p. 117.Google Scholar
34.Schultz, J. and Nardin, M. Theories and mechanisms of adhesion, in Adhesion Promotion Techniques edited by Mittal, K.L. and Pizzi, A. (Marcel Dekker, New York, 1999), Chap. 1, p. 8.Google Scholar
35.Gangopadhyay, U. and Wynblatt, P.: Modification of the gold/graphite interfacial energy by interfacial adsorption of nickel. J. Mater. Sci. 30, 94 (1995).CrossRefGoogle Scholar
36.Erb, U., Abel, W. and Gleiter, H.: The significance of atomic matching for the structure of interphase boundaries. Scripta Metall. 16, 1317 (1982).CrossRefGoogle Scholar
37.Hermann, G., Gleiter, H. and Baro, G.: Investigation of low energy grain boundaries in metals by a sintering technique. Acta Metall. 24, 353 (1976).CrossRefGoogle Scholar
38.Shirokoff, J. and Erb, U.: Detection of the complete set of preferred orientations of silver on sodium chloride. Scripta Metall. 20, 1607 (1986).CrossRefGoogle Scholar
39.Shirokoff, J., Cheung, J. and Erb, U.: On the usefullness of epitaxy experiments in evaluating interface models. Acta Metall. Mater. 38, 1273 (1990).CrossRefGoogle Scholar
40.Goodhew, P.J. and Smith, D.A.: Grooving at grain boundaries in thin films. Scripta Metall. 16, 91 (1982).CrossRefGoogle Scholar
41.Sprenger, J.W., Shirokoff, J. and Erb, U.: Preferred orientations of fcc metals on amorphous silica. Scripta Metall. 23, 1531 (1989).CrossRefGoogle Scholar
42.Kennefick, C.M. and Raj, R.: Copper on sapphire: Stability of thin films at 0.7 Tm. Acta Metall. 37, 2947 (1989).CrossRefGoogle Scholar
43.Soper, A., Gilles, B. and Eustathopoulos, N.: Work of adhesion and orientation relationships at the solid Cu/Al2O3 interface. Mater. Sci. Forum. 207–209, 433 (1996).CrossRefGoogle Scholar
44.McCafferty, K., Soper, A., Cheung, C., Shirokoff, J. and Erb, U.: Effect of temperature on preferred orientation of FCC metals on amorphous silica. Scripta Metall. Mater. 26, 1215 (1992).CrossRefGoogle Scholar
45.Soper, A., McCafferty, K. and Erb, U.: The effects of temperature and bismuth impurities on preferred orientations of copper and silver on amorphous silica. Phys. Status Solidi A 139, 371 (1993).CrossRefGoogle Scholar
46.Wang, Z. and Wynblatt, P.: Study of a reaction at the solid Cu/α–SiC interface. J. Mater. Sci. 33, 1177 (1998).CrossRefGoogle Scholar
47.Cheng, W-R. and Wu, Z-Q.: The TEM and SEM observations of the high temperature behavior of copper alloy films. Chin. Phys. 3, 299 (1983).Google Scholar
48.Ko, Y.K., Jang, J.H., Lee, S., Yang, H.J., Lee, W.H., Reucroft, P.J. and Lee, J.G.: Effects of molybdenum, silver dopants and a titanium substrate layer on copper film metallization. J. Mater. Sci. 38, 217 (2003).CrossRefGoogle Scholar
49.Masten, A. and Wissman, P.: Optical studies on thin copper films on Si(111). Appl. Surf. Sci. 179, 68 (2001).CrossRefGoogle Scholar
50.van der Straten, O., Zhu, Y., Dunn, K., Eisenbraun, E.T. and Kaloyeros, A.E.: Atomic layer deposition of tantalum nitride for ultrathin liner applications in advanced copper metallization schemes. J. Mater. Res. 19, 447 (2004).CrossRefGoogle Scholar
51.Chopra, H.D., Yang, D.X., Chen, P.J. and Egelhoff, W.F. Jr.: Surfactantassisted atomic-level engineering of spin valves. Phys. Rev. B 65, 094433–1 (2002).CrossRefGoogle Scholar
52.McLean, M.: Determination of the surface energy of copper as a function of crystallographic orientation and temperature. Acta Metall. 19, 387 (1971).CrossRefGoogle Scholar
53.Johnston, I.A., Dobson, P.S. and Smallman, R.E.: Void shrinkage and growth in quenched copper, and a determination of the surface energy. Cryst. Latt. Def. 1, 47 (1969).Google Scholar
54.Hara, T., Uchida, M., Fujimoto, M., Doy, T.K., Balakumar, S. and Babu, N.: Measurement of adhesion strength in copper interconnection layers. Electrochem. Solid-State Lett. 7, G28 (2004).CrossRefGoogle Scholar