CVD Boron Carbo-Nitride as Pore Sealant for Ultra Low-K Interlayer Dielectrics


Blanket porous methyl silsesquioxane (pMSQ) films on a Si substrate were studied with the intent to seal the pores and prevent penetration of a metallic precursor during barrier deposition. The blanket pMSQ films studied were approximately 220 nm thick and had been etched and ashed. When tantalum pentafluoride (TaF5) is exposed to an unsealed pMSQ sample, X-ray photoelectron spectroscopy (XPS) depth profiling and secondary ion mass spectroscopy (SIMS) depth profiling reveal penetration of Ta into the pores all the way to the pMSQ / Si interface. Boron carbo-nitride films were grown by thermal chemical vapor deposition (CVD) using dimethylamine borane (DMAB) precursor with Ar carrier gas and C2H4 coreactant. These films had a stoichiometry of BC0.9N0.07 and have been shown in a previous study to have a k value as low as 3.8. BC0.9N0.07 films ranging from 1.8 to 40.6 nm were deposited on pMSQ and then exposed to TaF5 gas to determine the extent of Ta penetration into the pMSQ. Ta penetration was determined by XPS depth profiling and sometimes SIMS depth profiling. XPS depth profiling of a TaF5 / 6.3 nm BC0.9N0.07 / pMSQ / Si film stack indicates the attenuation of the Ta signal to < 2 at. % throughout the pMSQ. Backside SIMS of this sample suggests that trace amounts of Ta (< 2 at. %) are due to knock-in by Ar ions used for sputtering. An identical film stack containing 3.9 nm BC0.9N0.07 was also successful at inhibiting Ta penetration even with a 370°C post-TaF5 exposure anneal, suggesting the stability of BC0.9N0.07 to thermal diffusion of Ta. All BC0.9N0.07 films thicker than and including 3.9 nm prevented Ta from penetrating into the pMSQ.

This is a preview of subscription content, access via your institution.


  1. 1

    International Technology Roadmap for Semiconductors 2004 update, SIA, San Jose, CA. 2004.

  2. 2

    W. Besling, A. Satta, J. Schuhmacher, T. Abell, V. Sutcliffe, A.-M. Hoyas, G. Beyer, D. Gravesteijn, and K. Maex , Proc. Inter. Interconnect Technol. Conf. (IITC) 2002, pp. 288–291.

  3. 3

    M.E. Thomas, D.M. Smith, S. Wallace, and N. Iwamoto, Proc. Inter. Interconnect Technol. Conf. (IITC) 2002, pp. 223–225.

  4. 4

    J. Rouquerol, D. Avnir, C.W. Fairbridge, D.H. Everett, J.H. Haynes, N. Pernicone, J.D.F. Ramsay, K.S.W. Sing, and K.K. Unger, Pure and Applied Chemistry 66 (8), 1739 (1994).

    CAS  Article  Google Scholar 

  5. 5

    T. Abell, D. Shamiryan, J. Schuhmacher, W. Besling, V. Sutcliffe, and K. Maex, Proceedings of Advanced Metallization Conference 2002, pp. 717–723.

  6. 6

    T. Abell and K. Maex, Microelectronic Engineering 76, 16 (2004).

  7. 7

    E.T. Ryan, J. Martin, K. Junker, J.J. Lee, T. Guenther, J. Wetzel, S. Lin, D.W. Gidley, and J. Sun, Proc. Inter. Interconnect Technol. Conf. (IITC) 2002, pp.27–29.

  8. 8

    J.J. Senkevich, C. Jezewski, D. Lu, W.A. Lanford, G.-C. Wang, and T.-M. Lu, Materials Researh Society 812, F.1.2.1 (2004).

    Google Scholar 

  9. 9

    F. Iacopi, Z. Tokei, Q.T. Le, D. Shamiryan, T. Conrad, B. Brijs, U. Kreissig, M. Van Hove, and K. Maex, Journal of Applied Physics 92 (3), 1548 (2002).

    CAS  Article  Google Scholar 

  10. 10

    F. Iacopi, M.R. Baklanov, E. Sleeckx, T. Conrad, H. Bender, H. Meynen, and K. Maex, Journal of Vacuum Science Technology B 20 (1), 109 (2002).

    Article  Google Scholar 

  11. 11

    K. Maex, M.R. Baklanov, D. Shamiryan, F. Iacopi, S.H. Brongersma, and Z.S. Yanovitskaya, Journal of Applied Physics 93 (11), 8793 (2003).

    CAS  Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to P. Ryan Fitzpatrick.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Fitzpatrick, P.R., Satyanarayana, S., Sun, Y. et al. CVD Boron Carbo-Nitride as Pore Sealant for Ultra Low-K Interlayer Dielectrics. MRS Online Proceedings Library 863, B6.8 (2004).

Download citation