Hostname: page-component-745bb68f8f-b6zl4 Total loading time: 0 Render date: 2025-01-26T05:03:43.739Z Has data issue: false hasContentIssue false
  • English
  • Français

Engineering the Al-Ti/p-SiC Ohmic Contact for Improved Performance

Published online by Cambridge University Press:  21 March 2011

J. Y. Lin ,
S. E. Mohney ,
M. Smalley ,
J. Crofton ,
J. R. Williams  and
T. Isaacs-Smith
J. Y. Lin
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802.
S. E. Mohney
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802.
M. Smalley
Affiliation:
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802.
J. Crofton
Affiliation:
Department of Physics and Engineering Physics, Murray State University, Murray, KY 42071 and Department of Electrical Engineering, The University of Kentucky, Lexington, KY 40506.
J. R. Williams
Affiliation:
Department of Physics, Auburn University, Auburn, AL 36849.
T. Isaacs-Smith
Affiliation:
Department of Physics, Auburn University, Auburn, AL 36849.
Get access

Abstract

The influence of composition on Al-Ti ohmic contacts to 4H p-SiC was studied. When NA was 7 x 1018 cm−3, contacts with 70 wt.% or more Al became ohmic when annealed at 1000°C for 2 min, whereas when there was 60 wt.% or less Al, the contacts did not become ohmic even when annealed under more severe conditions (longer times and/or higher temperatures). Spiking of the contact metallization always accompanied ohmic behavior and could be correlated with Al-Ti compositions that contain both an Al-rich liquid and solid TiAl3 at 1000°C prior to reaction with SiC or evaporative loss of Al. For the 70 wt.× contacts, a specific contact resistance of 1.5 × 10−4 Ω cm2 was measured along with spiking of the metallization into the SiC with a room-mean-square interfacial roughness of 150 Å and a maximum spiking depth of 1200 Å. Although still a concern, this spiking was less severe than observed for the 90 wt.× composition. A conductive CrB2 cap layer was next demonstrated to retard evaporation of Al during annealing of the Al-Ti contacts with 70 wt.× Al. The cap allowed use of thinner contact layers, reducing the depth of spiking and improving the surface morphology and edge definition of the ohmic contacts, with a one order of magnitude penalty in the specific contact resistance.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 640: Symposium H – Silicon Carbide-Materials, Processing, and Devices , 2000 , H7.3
Copyright
Copyright © Materials Research Society 2001

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Edmond, J. A., Ryu, J., Glass, J. T., and Davis, R. F., J. Electrochem. Soc. 135, 359 (1986).Google Scholar
2. Daimon, H., Yamanaka, M., Sakuma, E., Misawa, S., and Yoshida, S., Jpn. J. Appl. Phys. 25, L592 (1986).Google Scholar
3. Crofton, J., Barnes, P. A., Williams, J. R., and Edmond, J. A., Appl. Phys. Lett. 62, 384 (1993).Google Scholar
4. Dmitriev, V. A., Irvine, K., Spencer, M., Kelner, G., Appl. Phys. Lett. 64, 318 (1994).Google Scholar
5. Nordell, N., Savage, S., Schoner, A., Inst. Phys. Conf. Ser. 142, 573 (1996).Google Scholar
6. Crofton, J., Beyer, L., Williams, J. R., Luckowski, E. D., Mohney, S. E., and DeLucca, J. M., Solid-State Electron. 41, 1725 (1997).Google Scholar
7. Sam Liu and James Scofield, 4th International High Temperature Electronics Conference (IEEE, Piscataway, NJ, 1998), p. 88.Google Scholar
8. Kassamakova, L., Rakanakov, R., Nordell, N., and Savage, S., Mater. Sci. Forum 264–268, 787 (1998).Google Scholar
9. Braslau, N., J. Vacuum Sci. Technol. 19, 803 (1981).Google Scholar
10. Okamoto, H., J. Phase Equilibria 14, 120 (1993).Google Scholar
11. Villars, P., Prince, A., and Okamoto, H., Handbook of Ternary Alloy Phase Diagrams (ASM International, Materials Park, OH, 1995).Google Scholar
12. Villars, P. and Calvert, L. D., Pearson's Handbook of Crystallographic Data for Intermetallic Phases (ASTM International, Newbury, OH, 1991).Google Scholar
13. Ordan'yan, S. S., Dmitriev, A. I. and Kapitonova, I. M., Inorganic Materials 27, 134 (1991)Google Scholar
14. Cuttler, R. A., in Engineered Materials Handbook, Vol.4 (ASM International, Materials Park, OH, 1991), p. 787.Google Scholar