Physical Vapor Deposition Barriers for Cu metallization - PVD Barriers

  • Junichi KoikeEmail author


Cu is an interstitial impurity in Si and its diffusivity in Si is faster than other transition metals and of the order of 10−5 to 10−7 cm2/s in the temperature range of 200–500°C [1]. Electronically, Cu is a deep-level dopant in Si and forms various donor and acceptor levels, inducing current leakage [2, 3]. In a multilayered device structure, Cu diffuses through a dielectric layer and reaches a Si substrate under electric bias field [4]. In order to prevent Cu diffusion, a barrier layer is necessary at an interface between Cu and the dielectric layers. By the use of high-resistivity barrier metal, the effective resistivity of interconnect lines increases with the advancement of the technology node as shown in Fig. 21.1 [5, 6]. For a fixed barrier thickness of 10 nm, for example, effective resistivity increases rapidly from 2.35 μΩ cm for the 65 nm node to 2.85 μΩ cm for the 32 nm node. Meanwhile, the effective resistivity of 2.2 μΩ cm should be maintained in order to minimize RC delay [7]. This recommendation by the International Technology Roadmap for Semiconductors (ITRS) determines a required barrier thickness at a given technology node. In the 32 nm node, the barrier thickness should be 3.5 nm, approximately 10 atomic layers to prevent interdiffusion between Cu and the dielectric layer. In order to achieve this requirement, a proper barrier material should be deposited using proper deposition techniques and conditions. Wang et al. summarized the published data as of the year 1993 together with their investigation of TiW barrier [8]. Kaloyeros and Eisenbraun [9] published an excellent review of barrier materials as of 2000. In their review article, advantages and limitations of various barrier materials were described in detail based on numerous experimental works by others. Readers can find in this article how and why Ta/TaN barrier had come to use for the Cu interconnect. Since then, technology has rapidly advanced along the line of the ITRS roadmap. Once the technology node entered to a sub-micrometer range, barrier thickness becomes a critical issue to ensure expected performance and reliability of advanced devices. Barrier materials and processes need to be revisited from fundamental viewpoint. In this chapter, the issues of physical vapor deposited (PVD) barrier will be discussed in terms of metallurgical and thermodynamic aspects.


Contact Angle Activity Coefficient Barrier Layer Barrier Material Barrier Thickness 
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  1. 1.
    Graff, K.: Metal Impurities in Silicon-Device Fabrication, Springer-Verlag, Berlin, 29 (1999)Google Scholar
  2. 2.
    Collins, C. B. and Carlson, R. O.: Properties of silicon doped with iron or copper. Phys. Rev. 108, 1405 (1957)CrossRefGoogle Scholar
  3. 3.
    Toyama, N.: Copper impurity levels in silicon. Solid State Electron. 26(1), 37 (1983)CrossRefGoogle Scholar
  4. 4.
    Shacham-Diamond, Y.; Dedhia, A.; Hoffstetter, D.; and Oldham, W. G.: Copper transport in thermal SiO2. J. Electrochem. Soc. 140(8), 2427 (1993)CrossRefGoogle Scholar
  5. 5.
    Kapur, P.; McVittie, J. P.; and Saraswat, K. C.: Technology and reliability constrained future copper interconnects-part I: Resistance modeling. IEEE Trans. Electron Devices 49(4), 590 (2002)CrossRefGoogle Scholar
  6. 6.
    Shibata, H.: Practical roadmap and approach of multi-level interconnect technology for realizing over GHz system-on-chip. Proceedings of International Symposium on ULSI Process Integration of the 199th Electro-Chemical Society Meeting. 430 (2001)Google Scholar
  7. 7.
    International Technology Roadmap for Semiconductors (2003)Google Scholar
  8. 8.
    Wang, S-Q.; Suthat, S.; Hoeflich, K.; and Burrow, B. J.: Diffusion barrier properties of TiW between Si and Cu. J. Appl. Phys. 73(5), 2301 (1993)CrossRefGoogle Scholar
  9. 9.
    Kaloyeros, A. E. and Eisenbraun, E.: Ultrathin diffusion barriers/liners for gigascale copper metallization. Annu. Rev. Mater. Sci. 30, 363 (2000)CrossRefGoogle Scholar
  10. 10.
    Iwamori, S.; Miyashita, T.; Fukuda, S.; Fukuda, N.; and Sudoh, K.: Effect of a metallic interfacial layer on peel strength deterioration between a Cu thin film and a polyimide substrate. J. Vac. Sci. Technol. B 15(1), 53 (1997)CrossRefGoogle Scholar
  11. 11.
    Gjostein, N. A.: Diffusion in Metals. Westerville, OH, ASM (1973)Google Scholar
  12. 12.
    Holloway, K.; Fryer, P. M.; Cabral. C.; Harper, J. M.; Bailey, P. J.; and Kelleher, K. H.: Tantalum as a diffusion barrier between copper and silicon: Failure mechanism and effect of nitrogen additions. J. Appl. Phys. 71(11), 5433 (1992)CrossRefGoogle Scholar
  13. 13.
    Choe, H. S. and Danek, M.: MOCVD TiN diffusion barriers for copper interconnects. Proc. IEEE Int. Interconnect Technology Conference 62 (1999)Google Scholar
  14. 14.
    Olowolafe, J.; Mogab, C.; Gregory, R.; and Kottke, M.: Interdiffusions in Cu/reactive-ion-sputtered TiN, Cu/chemical-vapor-deposited TiN, Cu/TaN, and TaN/Cu/TaN thin-film structures: Low temperature diffusion analyses. J. Appl. Phys. 72(9), 4099 (1992)CrossRefGoogle Scholar
  15. 15.
    Ko, D.; Park, B.; Kim, Y.; Ha, J.; and Park, Y.: Advanced Metallization and Interconnect Systems for ULSI Applications in 1995, Mater. Res. Soc., Pittsburgh, 257 (1996)Google Scholar
  16. 16.
    Bai, G.; Wittenbrock, S.; Ochoa, V.; and Bohr, M.: Effectiveness and reliability of metal diffusion barriers for copper interconnects. Mater. Res. Soc. Symp. Proc. 403, 501 (1996)Google Scholar
  17. 17.
    Kim, K.: Advanced Metallization and Interconnect Systems for ULSI Applications. Mater. Res. Soc., Pittsburgh, 281 (1995)Google Scholar
  18. 18.
    Min, K.-H.; Chun, K.-C.; and Kim, K.-B.: Comparative study of tantalum and tantalum nitrides (Ta2N and TaN) as a diffusion barrier for Cu metallization. J. Vac. Sci. Technol. B 14(5), 3263 (1996)CrossRefGoogle Scholar
  19. 19.
    Eustathopoulos, N.; Nicholas, M. G.; and Drevet, B.: Wettability at High Temperatures, Pergamon, Amsterdam (1999)Google Scholar
  20. 20.
    Naidich, Yu. V.: Wettability of solids by molten metals. In Progress in Surface and Membrane Science. Cadenhead, D. A. and Danielli, J. F., Eds. Academic Press, New York, 14, 353 (1981)Google Scholar
  21. 21.
    Chatain, D.; Rivollet, I.; and Eustathopoulos, N.: Thermodynamic adhesion in nonreactive liquid metal-alumina systems. J. Chem. Phys. 83, 561 (1986)Google Scholar
  22. 22.
    Naidich, Yu. V.: Contact phenomena in molten metals. Naukova Dumka; Kiev (1972)Google Scholar
  23. 23.
    Naidich, Yu. V.: Wettability of halides with molten metals, Physico-chemical and practical aspects. Powder Metallurgy and Metal Ceramics 39, 355 (2000)CrossRefGoogle Scholar
  24. 24.
    Naidich, Yu. V. and Taranets, N. Y.: Wettability of aluminum nitride by tin aluminum melts. J. Mater. Sci. 33, 3993 (1998)CrossRefGoogle Scholar
  25. 25.
    Ljunberg, L. and Warren, R.: Wetting of silicon nitride with. selected metals and alloys. Ceram. Eng. Sci. Proc. 10, 1655 (1989)CrossRefGoogle Scholar
  26. 26.
    Nicholas, M. G.; Mortimer, D. A.; Jones, L. M.; and Crispin, R. M.: Some observations on the wetting and bonding of nitride ceramic. J. Mater. Sci. 25, 2679 (1990)CrossRefGoogle Scholar
  27. 27.
    Ramqvist, L.: Wetting of Metallic Carbides by Liquid Copper, Nickel, Cobalt and Iron. Int. J. Powder Metall. 1(4), 2 (1965)Google Scholar
  28. 28.
    Sinke, W.; Frijlink, P.; and Saris, F.: Oxygen in titanium nitride diffusion barriers. Appl. Phys. Lett. 47(5), 471 (1985)CrossRefGoogle Scholar
  29. 29.
    Park, K. and Kim, K.: Comparative Study on the Titanium Nitride (TiN) As a diffusion Barrier Between Al/Si and Cu/Si: Failure Mechanism and Effect of `Stuffing. Mater. Res. Soc. Symp. Proc. 391, 211 (1995)Google Scholar
  30. 30.
    Doussin, L. and Omnes, J.: Technical report (report 1/1259 M), Office National d’Etudes et de Recherches Aerospariales, Direction des Materiaux, Chatillon, France (1967)Google Scholar
  31. 31.
    Nicholas, M. and Poole, D. M.: The influence of oxygen on wetting and bonding in Cu-W sys-. Tem. J. Mater. Sci. 2(3), 269 (1967)CrossRefGoogle Scholar
  32. 32.
    Lane, M. W.; Liniger, E. G.; and Lloyd, J. R.: Relationship between interfacial adhesion and electromigration in Cu metallization. J. Appl. Phys. 93(3), 1417 (2003)CrossRefGoogle Scholar
  33. 33.
    Rossnagel, S. M.: Sputter deposition for semiconductor: Manufacturing. IBM J. Res. Develp. 43, 163 (1999)CrossRefGoogle Scholar
  34. 34.
    Cuomo, J. J. and Rossnagel, S. M.: Hollow Cathode Enhanced Magnetron Sputtering. J. Vac. Sci. Technol. A 4, 393 (1986)CrossRefGoogle Scholar
  35. 35.
    Liu, D.; Dew, S. K.; Brett, M. J.; Janacek, T.; Smy, T.; and Tsai, W.: Experimental study and computer simulation of collimated sputtering of titanium thin films over topographical features. J. Appl. Phys. 74(2), 1339 (1993)CrossRefGoogle Scholar
  36. 36.
    Mayo, A. A.; Hamaguchi, S.; Joo, J. H.; and Rossnagel, S. M.: Across-wafer nonuniformity of long throw sputter deposition. J. Vac. Sci. Technol. B 15, 1788 (1997)CrossRefGoogle Scholar
  37. 37.
    Smy, T.; Tang, L.; Chan, K.; Tait, R. N.; Broughton, J. N.; Dew, S. K.; and Brett, M. J.: A simulation study of long throw sputtering for diffusion barrier deposition into high aspect vias and contacts. IEEE Trans. Electron Devices 45, 1414 (1998)CrossRefGoogle Scholar
  38. 38.
    Rossnagel, S.; Mikalsen, D.; Kinoshita H.; and Cuomo, J. J.: Collimated magnetron sputter deposition. J. Vac. Sci. Technol. A 9(2), 261 (1991)CrossRefGoogle Scholar
  39. 39.
    Motegi, N.; Kahimoto, Y.; Nagatani, K.; Takahashi, S.; Kondo, T.; Mizusawa, Y.; and Nakayama, I.: Long-throw low-pressure sputtering technology for very large-scale integrated devices. J. Vac. Sci. Technol. B 13(4), 1906 (1995)CrossRefGoogle Scholar
  40. 40.
    Broughton, J. N.; Brett, M. J.; Dew, S. K.; and Este, G.: Titanium sputter deposition at low pressures and long throw distances. IEEE Trans. Semiconduct. Manufact. 96, 122 (1996)CrossRefGoogle Scholar
  41. 41.
    Yamashita, M.: Sputter Type High Frequency Ion Source for Ion Beam … Sputtering Apparatus. J. Vac. Sci. Technol. A 7, 151 (1989)CrossRefGoogle Scholar
  42. 42.
    Rossnagel, S. M. and Hopwood, J. H.: Magnetron sputter deposition with levels of metal ionization. Appl. Phys. Lett. 63, 3285 (1993)CrossRefGoogle Scholar
  43. 43.
    Hamaguchi, S. and Rossnagel, S. M.: Liner conformality in ionized magnetron sputter metal deposition process. J. Vac. Sci. Technol. B 14, 2603 (1996)CrossRefGoogle Scholar
  44. 44.
    Sugiyama, K.; Pac, S.; Takahashi, Y.; and Motojima, S.: LowTempera-ganometallic. Compounds. J. Electrochem. Soc. 122, 1545 (1975)CrossRefGoogle Scholar
  45. 45.
    Fix, R.; Gordon, R.; and Hoffman, D.: Chemical vapor deposition of vanadium and tantalum nitride thin films. Chem. Matter. 5, 614 (1993)CrossRefGoogle Scholar
  46. 46.
    Tsai, M.; Sun, S.; Tsai, C.; Chuan, S.; and Chiu, H.: Comparison of the diffusion barrier properties of chemical-vapor-deposited TaN and sputtered TaN between Cu and Si. J. Appl. Phys. 79(9), 6932 (1996)CrossRefGoogle Scholar
  47. 47.
    Kim, H.: Atomic layer deposition of metal and nitride thin films: Current research efforts and applications for semiconductor device processing. J. Vac. Sci. Technol. B 21(6), 2231 (2003)CrossRefGoogle Scholar
  48. 48.
    Krishnamoothy, A.; Chanda, K.; Murarka, S. P.; Ryan, J.; and Ramanath, G.: Self-assembled near-zero-thickness molecular layers as diffusion barriers for Cu metallization. Appl. Phys. Lett. 78(17), 2467 (2001)CrossRefGoogle Scholar
  49. 49.
    Ganesan, P. G.; Gamba, J.; Ellis, A.; Kane, R. S.; and Ramanath, G.: Polyelectrolyte nanolayers as diffusion barriers for Cu metallization. Appl. Phys. Lett. 83(16), 3302 (2003)CrossRefGoogle Scholar
  50. 50.
    Mikami, N.; Hata, N.; Kikkawa, T.; and Machida, H.: Robust self-assembled monolayer as diffusion barrier for copper metallization. Appl. Phys. Lett. 83(25), 5181 (2003)CrossRefGoogle Scholar
  51. 51.
    Ding, P. J.; Lanford, W. A.; Hymes, S.; and Murarka, S. P.: Room-temperature continuous-wave operation of a single-layered 1.3 μm quantum dot laser. Appl. Phys. Lett. 75(21), 3267 (1994)Google Scholar
  52. 52.
    Lanford, W. A.; Ding, P. J.; Wang, W.; Hymes, S.; and Murarka, S. P.: Low-temperature passivation of copper by doping with Al or Mg. Thin Solid Films 62(1–2), 234 (1995)CrossRefGoogle Scholar
  53. 53.
    Smithells Metals Reference Book, 7th Ed., Brandes, E. A.; and Brook, G. B., eds. Butterworth Heinemann (1992)Google Scholar
  54. 54.
    Frederick, M. J. and Ramanath, G.: Kinetics of interfacial reaction in Cu–Mg alloy films on SiO2. J. Appl. Phys. 95(1), 363 (2004)CrossRefGoogle Scholar
  55. 55.
    Hino, M.; Nagasaka T.; and Takehama, R.: Activity measurement of the constituents in liquid Cu-Mg and Cu-Ca alloys with mass spectrometry. Metall. Mater. Trans. 31B, 927 (2000)Google Scholar
  56. 56.
    Jacob, K. T.; Priya, S.; and Waseda, Y.: A thermodynamic study of liquid Cu-Cr alloys and metastable liquid immiscibility. Z. Metallkd. 91(7), 594 (2000)Google Scholar
  57. 57.
    Lewin, K.: Thermodynamic study of the Cu-Mn system. Scan. J. Metall. 22, 310 (1993)Google Scholar
  58. 58.
    Oyamada, H.; Nagasaka, T.; and Hino, M.: Activity measurement of the constituents in liquid Cu-Al alloy with mass-spectrometry. Mater. Trans. 12, 1225 (1998)Google Scholar
  59. 59.
    Witusiewicz, V; Arpshofen, I; and Sommer, F.: Thermodynamics of liquid Cu-Si and Cu-Zr alloys. Z. Metallkd. 91, 594 (2000)Google Scholar
  60. 60.
    Katayama, I.; Shimatani, H.; and Kouzuka, Z.: Thermodynamic Study of Solid Cu-Ni and Ni-Mo Alloys by E. M. F. Measurements using the solid electrolyte. J. Jpn. Inst. Metall. 37(5), 509 (1973)Google Scholar
  61. 61.
    Azakami T. and Yazawa. A.: Activity measurements of liquid copper binary alloys. Can. Metall. Quart. 15, 111 (1976)Google Scholar
  62. 62.
    Hondros, E. D. and Seah, M. P.: In Physical Metallurgy. Cahn, R. W. and Haasen, P., Eds. North-Holland, Amsterdam 855 (1983)Google Scholar
  63. 63.
    Landolt-Bornstein: Numerical Data and Functional Relationships in Science and Technology, New Series, Group III: Crystal and Solid State Physics, Vol. 26, Diffusion in Solid Metals and Alloys, ed. by H. Mehrer, Springer, Berlin, 185 (1990)Google Scholar
  64. 64.
    Koike, J. and Wada, M.: Self-forming diffusion barrier layer in Cu–Mn alloy metallization. Appl. Phys. Lett. 87(4), 041911 (2005)CrossRefGoogle Scholar
  65. 65.
    Koike, J.; Haneda, M.; Iijima, J.; Otsuka, Y.; Sako, H.; Neishi, K.: Growth kinetics and thermal stability of a self-formed barrier layer at Cu-Mn/SiO2 interface. J. Appl. Phys. 102(4), 043527 (2007)CrossRefGoogle Scholar
  66. 66.
    Usui, T.; Nasu, H.; Takahashi, S.; Shimizu, N.; Nishikawa, T.; Yoshimaru, M.; Shibata, H.; Wada, M.; and Koike, J.: Highly reliable copper dual-damascene interconnects with self-formed MnSixOy barrier Layer. IEEE Trans Electron Devices 53(10), 2492 (2006)CrossRefGoogle Scholar

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© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Department of Materials ScienceTohoku UniversitySendaiJapan

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