ALD of Al2O3 for Carbon Nanotube vertical interconnect and its impact on the electrical properties


Because of their superior electronic properties and bottom-up growth mode, Carbon Nanotubes (CNT) may offer a valid alternative for high aspect ratio vertical interconnects in future generations of microchips. For being successful, though, CNT based interconnects must reach sufficiently low values of resistance to become competitive with current W or Cu based technologies. This essentially means that CMOS compatible processes are needed to produce dense CNT shells of extremely high quality with almost ideal contacts. Moreover, their electrical properties must be preserved at every process step in the integration of CNT into vertical interconnect structures. In this work this latter aspect is analyzed by studying the changes in the electrical characteristics when encapsulating CNT into different oxides. Oxide encapsulation is often exploited to hold the CNT in place and to avoid snapping during a polishing step. On the other hand, oxide encapsulation can influence the properties of the grown CNT which are directly exposed to possibly harmful oxidative conditions. Two different deposition techniques and oxides were evaluated: Chemical Vapor Deposition (CVD) of SiO2 (reference) and Atomic Layer Deposition (ALD) of Al2O3 in less aggressive oxidizing conditions. The two processes were transferred to CNT interconnect test structures on 200mm wafers and electrically benchmarked. The CNT resistance was measured in function of the CNT length which allows the extraction and individual distinction of the resistive contributions of the CNT and the contacts. It is shown that the encapsulating SiO2 deposited by CVD degrades the resistance of CNT by altering their quality. Directions for future improvements have been identified and discussed.

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


  1. [1]

    K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I. Katsnelson,I. V. Grigorieva, S. V. Dubonos, and A. A. Firsov, Nature 438, 197 (2005).

    Article  Google Scholar 

  2. [2]

    A. K. Geim, K.S. Novoselov The rise of graphene Nat. Mater. 6, 183 (2007).

    CAS  Article  Google Scholar 

  3. [3]

    K. S. Novoselov , A. K. Geim,S. V. Morozov,D.Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva and A. A. Firsov, Science 306, 666 (2004).

    CAS  Article  Google Scholar 

  4. [4]

    M. D. Stoller, S. J. Park, Y. W. Zhu, J. H. An, and R. S. Ruoff, Nano Lett. 8, 3498 (2008).

    CAS  Article  Google Scholar 

  5. [5]

    Y. M. Lin, K. A. Jenkins, A. Valdes-Garcia, J. P. Small, D. B. Farmer, and P. Avouris, Nano Lett. 9, 422 (2009).

    Article  Google Scholar 

  6. [6]

    F. Schedin, A. K. Geim, S. V. Morozov, E. W. Hill, P. Blake, M. I. Atsnelson and K. S. Novoselov Nat. Mater. 6, 652 (2007).

    Article  Google Scholar 

  7. [7]

    K. S. Kim, Y. Zhao, H. Jang, S. Y. Lee, J. M. Kim, K. S. Kim, J. H. Ahn, P. Kim, J. Y. Choi, and B. H. Hong, Nature 457, 706 (2009)

    CAS  Article  Google Scholar 

  8. [8]

    X. Wang, L. J. Zhi, and K. Mullen, Nano Lett. 8, 323 (2008).

    CAS  Article  Google Scholar 

  9. [9]

    S. Bae, H. Kim, Y. Lee, X. Xu, J. Park, Y. Zheng,J. Balakrishnan, T. Lei, H. R. Kim, Y. I. Song, Y. Kim, K. S. Kim, B. Ö zyilmaz, J. Ahn, B. H. Hong and S. Iijima, Nat. Nanotechonol., 5, 574–578 (2010)

    CAS  Article  Google Scholar 

  10. [10]

    G. Hwang, J. C. Acosta, E. Vela, S. Haliyo and S. Régnier, International Symposium on Optomechatronic Technologies, 21–23, 169–174 (2009).

    CAS  Article  Google Scholar 

  11. [11]

    J. Wu, H. A. Becerril, Z. Bao, Z. Liu, Y. Chen, and P. Peumans, Appl.Phys. Lett. 92, 263302 (2008).

    CAS  Article  Google Scholar 

  12. [12]

    H. Yamaguchi, G. Eda, C. Mattevi, H. Kim, and M. Chhowalla, ACS Nano 4, 524 (2010).

    Article  Google Scholar 

  13. [13]

    I. Lahiri, R. Seelaboyina, J. Y. Hwang, R. Banerjee, and W. Choi, Carbon 48, 1531 (2010).

    CAS  Article  Google Scholar 

  14. [14]

    X. S. Li, W. W. Cai, J. H. An, S. Kim, J. Nah, D. X. Yang, R. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, Science 324, 1312 (2009).

    CAS  Article  Google Scholar 

  15. [15]

    V. P. Verma, S. Das, I. Lahiri, and W. Choi, Appl.Phys. Lett. 96, 203108 (2010).

Download references

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

Chiodarelli, N., Delabie, A., Masahito, S. et al. ALD of Al2O3 for Carbon Nanotube vertical interconnect and its impact on the electrical properties. MRS Online Proceedings Library 1283, 1010 (2010).

Download citation