| AVS 62nd International Symposium & Exhibition | |
| Electronic Materials and Processing | Wednesday Sessions |
| Session EM-WeA |
| Session: | Interconnects: Methods and Materials for Removing Connectivity Constraints |
| Presenter: | Yusuke Abe, Santa Clara University |
| Authors: | Y. Abe, Santa Clara University A. Vyas, Santa Clara University R. Senegor, Santa Clara University C. Yang, Santa Clara University |
| Correspondent: | Click to Email |
Nanocarbons such as carbon nanotubes (CNTs) and graphene are candidate materials for next-generation integrated circuit technologies due to their high current-carrying capacities and excellent electrical, thermal, and mechanical properties [1,2]. The key performance-limiting factor continues to be the high contact resistance at the interface with metal electrodes [3]. Metal depositions are frequently used during post-fabrication contact engineering for these nanocarbons to mitigate the high resistances between these materials and metal electrodes, with various degrees of success in achieving stable low-resistance contacts [4]. We have fabricated test devices for CNT vias, and measured their current-voltage (I-V) characteristics [5]. In this study, post-fabrication contact engineering is performed using electron-beam induced deposition of tungsten (EBID-W) [6] to improve the electrode contacts and hence reduce the total device resistance.
Fabrication of these via test structures without top contact metallization was described elsewhere [5]. In the present study, EBID-W is used to form the via top contacts (Fig. 1). From I-V and resistance measurements on 500 nm x 500 nm CNT vias with and without EBID-W top contact metallization, the effect of EBID-W contact on resistance reduction is clearly demonstrated (Fig. 2). While similar improvement can be obtained by current stressing without contact metallization [5], such technique would introduce an additional thermal cycle to the chip fabrication process and hence undesirable. On the other hand, the resistance of a via with W top contact is shown to have reached its minimum which is unaffected by further annealing (Fig. 3). Thus the contact resistance of the CNT via is indeed improved by top contact metallization with W, and that the resistance is stable. Without increasing the thermal budget from current stressing in chip fabrication, the use of EBID-W for via top contact metallization could facilitate the eventual functionalization of CNT via interconnects.
REFERENCES
[1] T. Saito, T. Yamada, D. Fabris, H. Kitsuki, P. Wilhite, M. Suzuki, and C.Y. Yang, Appl. Phys. Lett. 93, 102108 (1-3), 2008.
[2] M. S. Dresselhaus, G. Dresselhaus, and P. Avouris, Berlin, New York, Springer, 2001.
[3] F. Wakaya, K. Katayama, and K. Gamo, Microel. Eng. 67–68, 853–857, 2003.
[4] P. Wilhite, A.A. Vyas, J. Tan, J. Tan, T. Yamada, P. Wang, J. Park, and C.Y. Yang, Semicond. Sci. Technol. 29, 054006 (16pp), 2014.
[5] C. Zhou, A.A. Vyas, P. Wilhite, P. Wang, M. Chan, and C.Y. Yang, Electron Device Lett. 36, 71-73, 2015.
[6] S.J. Randolph, J.D. Fowlkes, and P.D. Rack, Crit. Rev. Solid State Mater. Sci. 31, 55-89, 2006.