Abstract
The efficiency of Ta and Nb films as diffusion barriers between thin Cu film and Si substrate has been studied using Auger electron spectroscopy, X-ray diffraction, optical microscopy, scanning electron microscopy and sheet resistance measurements. Two kinds of system were prepared by electron-beam evaporation: Cu/Ta (or Nb)/Si and Cu/Ta (or Mb) SiO2/Si. The samples were annealed at temperatures from 400 to 800‡C in a vacuum of 1 × 10−7 torr (13 ΜPa) for 30 min. In the Cu/Ta (or Nb)/Si system, the thermal stability was determined by interdiffusion at local sites, forming suicides, whereas the Cu/Ta (or Nb)/SiO2/Si system degraded by interdiffusion at the interface between Ta (or Nb) and Cu. It appears that Ta is a more effective diffusion barrier than Nb for both kinds of system. This difference in the barrier effect of the transition metals is attributed to differences between oxygen segregation at grain boundaries of barrier layers and differences between diffusion coefficients through barrier layers. It is suggested that the driving force for interdiffusion may play a major role in the reaction that determines the thermal stability of a given contact system; this suggestion is based on the fact that the interdiffusion in Cu/barrier/Si systems is suppressed by interposing an SiO2 layer in the Si substrate.
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H. MIYAZAKI, K. HINODE, Y. HOMMA and K. MUKAI, Jpn. J. Appl. Phys. 48 (1987) 329.
J. D. MCBRAYER, R. M. SWANSON and T. W. SIGMON, J. Electrochem. Soc. 123 (1986) 1242.
C.-A. CHANG, J. Appl. Phys. 67 (1990) 566.
L. STOLT, F. M. D'HEURLE and J. M. E. HARPER, Thin Solid Films 200 (1991) 147.
A. CROS, M. O. ABOELFOTOH and K. N. TU, J. Appl. Phys 67 (1990) 3328.
J. LI, Y. SHACHAM-DIAMOND and J. W. MAYER, Mater. Sci. Rep. 9 (1992) 1.
S. Q. WANG, MRS Bull. AuG. (1994) 30.
H. P. KATTELUS, and M.-A. NICOLET, in “Diffusion Phenomena in Thin Films and Microelectronic Materials”, edited by D. Gupta and P. S. Ho (Noyes, NJ, 1988) p. 432.
C.-A. CHANG, J. Vac. Sci. Technol. A8 (1990) 3796.
K. HOLLOWAY, P. M. FRYER, C. CABRAL Jr, J. M. E. HARPER, P. J. BAILEY and K. H. KELLEHER, J. Appl. Phys. 71 (1992) 5433.
L. A. CLEVENGER, N. A. BOJARCZUK, K. HOLLOWAY, J. M. E. HARPER, C. CABRAL Jr, R. G. SCHAD, F. CARDONE and L. STOLT, J. Appl. Phys. 73 (1993) 300.
K. HOLLOWAY and P. M. FRYER, Appl. Phys. Lett. 57 (1990) 1736.
E. KOLAWA, J. S. CHEN, J. S. REID, P. J. POKELA and M.-A. NICOLET, J. Appl. Phys. 70 (1991) 1369.
P. CATANIA, J. P. DOYLE and J. CUOMO, J. Vac. Sci. Technol. A10 (1992) 3318.
H. ONO, T. NAKANO and T. OHTA, Appl. Phys. Lett. 64 (1994) 1511.
N. Mattoso FILHO, C. ACHETE and F. L. FREIRE Jr., Thin Solid Films 220 (1992) 184.
C.-A. CHANG, J. Appl. Phys. 67 (1990) 6184.
L. C. LANE, T. C. NASON, G.-R. YANG, T.-M. LU and H. BAKHRU, J. Appl. Phys. 69 (1991) 6716.
A. J. BEVOLE, G. J. CAMPISI, H. R. SHANKS and F. A. SCHMIDT, J. Appl. Phys. 51 (1980) 5390.
S. Q. WANG and J. W. MAYER, J. Appl. Phys. 67 (1990) 2932.
K. N. TU and J. W. MAYER, in Thin Films — interdiffusion and reactions, edited by J. M. Poate, K. N. Tu and J. W. Mayer (Wiley, New York, 1978) Ch. 12.
G. OTTAVIANI and J. W. MAYER, in Reliability and Degradation: Device and Circuits, edited by M. J. Howes and D. V. Morgan (Wiley, New York, 1981) p.
O. KUBASCHEWSKI and B. E. Hopkins (eds) Oxidation of Metals and Alloys, 2nd Edn(Butterworth, London, 1962).
R. P. ELLIOTT, “Constitution of Binary Alloys, First Supplement” (McGraw-Hill, New York, 1965).
D. A. PORTER and K. E. EASTERLING (eds) Phase Transformation in Metals and Alloys (Van Nostrand Reinhold, New York, 1981).
T. B. MASSALSKI, “Binary Alloy Phase Diagram”, 2nd Edn (ASM/NIST, town, 1986).
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Jang, SY., Lee, SM. & Baik, HK. Tantalum and niobium as a diffusion barrier between copper and silicon. J Mater Sci: Mater Electron 7, 271–278 (1996). https://doi.org/10.1007/BF00188954
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DOI: https://doi.org/10.1007/BF00188954