Hostname: page-component-8448b6f56d-sxzjt Total loading time: 0 Render date: 2024-04-17T21:35:05.490Z Has data issue: false hasContentIssue false
  • English
  • Français

Nitrogen Passivation of the Interface States Near the Conduction Band Edge in 4H-Silicon Carbide

Published online by Cambridge University Press:  21 March 2011

J. R. Williams ,
G. Y. Chung ,
C. C. Tin ,
K. McDonald ,
D. Farmer ,
R. K. Chanana ,
R. A. Weller ,
S. T. Pantelides ,
O. W. Holland  and
M. K. Das
...Show all authors
J. R. Williams
Affiliation:
Physics Department, Auburn University, AL 36849
G. Y. Chung
Affiliation:
Physics Department, Auburn University, AL 36849
C. C. Tin
Affiliation:
Physics Department, Auburn University, AL 36849
K. McDonald
Affiliation:
Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235
D. Farmer
Affiliation:
Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235
R. K. Chanana
Affiliation:
Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235
R. A. Weller
Affiliation:
Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN 37235
S. T. Pantelides
Affiliation:
Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
O. W. Holland
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
M. K. Das
Affiliation:
Cree Research, Inc., Durham, NC 27713
L. A. Lipkin
Affiliation:
Cree Research, Inc., Durham, NC 27713
L. C. Feldman
Affiliation:
Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
Get access

Abstract

This paper describes the development of a nitrogen-based passivation technique for interface states near the conduction band edge [Dit(Ec)] in 4H-SiC/SiO2. These states have been observed and characterized in several laboratories for n- and p-SiC since their existence was first proposed by Schorner, et al. [1]. The origin of these states remains a point of discussion, but there is now general agreement that these states are largely responsible for the lower channel mobilities that are reported for n-channel, inversion mode 4H-SiC MOSFETs. Over the past year, much attention has been focused on finding methods by which these states can be passivated. The nitrogen passivation process that is described herein is based on post-oxidation, high temperature anneals in nitric oxide. An NO anneal at atmospheric pressure, 1175°C and 200–400sccm for 2hr reduces the interface state density at Ec-E ≅0.1eV in n-4H-SiC by more than one order of magnitude - from > 3×1013 to approximately 2×1012cm−2eV−1. Measurements for passivated MOSFETs yield effective channel mobilities of approximately 30–35cm2/V-s and low field mobilities of around 100cm2/V-s. These mobilities are the highest yet reported for MOSFETs fabricated with thermal oxides on standard 4H-SiC and represent a significant improvement compared to the single digit mobilities commonly reported for 4H inversion mode devices. The reduction in the interface state density is associated with the passivation of carbon cluster states that have energies near the conduction band edge. However, attempts to optimize the the passivation process for both dry and wet thermal oxides do not appear to reduce Dit(Ec) below about 2×1012cm−2eV−1 (compared to approximately 1010cm−2eV−1 for passivated Si/SiO2). This may be an indication that two types of interface states exist in the upper half of the SiC band gap – one type that is amenable to passivation by nitrogen and one that is not. Following NO passivation, the average breakdown field for dry oxides on p-4H-SiC is higher than the average field for wet oxides (7.6MV/cm compared to 7.1MV/cm at room temperature). However, both breakdown fields are lower than the average value of 8.2MV/cm measured for wet oxide layers that were not passivated. The lower breakdown fields can be attributed to donor-like states that appear near the valence band edge during passivation.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 640: Symposium H – Silicon Carbide-Materials, Processing, and Devices , 2000 , H3.5
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. Schorner, R., Friedrichs, P., Peters, D. and Stephani, D., IEEE Electron Device Lett. 20, 241 (1999).Google Scholar
2. EMIS Data Reviews Series No. 13, ed. Harris, G. L. (Short Run Press, Exeter, England, 1995).Google Scholar
3. Chung, G.Y., Tin, C.C., Won, J.H. and Williams, J.R., Materials Science Forum 338–342, 1097 (2000).Google Scholar
4. Das, M.K., Um, B.S. and Cooper, J.A. Jr, Materials Science Forum 338–342, 1069 (2000).Google Scholar
5. Saks, N.S., Mani, S.S. and Agarwal, A.K., Appl. Phys. Lett. 76(10), 2250 (2000).Google Scholar
6. Afanasev, V.V., Bassler, M., Pensl, G. and Schulz, M., Phys. Stat. Sol. (A) 162, 321 (1997).Google Scholar
7. Jernigan, G.G., Stahlbush, R.E., Das, M.K., Cooper, J.A. and Lipkin, L.A., Appl. Phys. Lett. 74(10), 1448 (1999).Google Scholar
8. Sridevan, S. and Baliga, B.J., IEEE Electron Device Lett. 19(7), 228 (1998).Google Scholar
9. Ogino, S., Oikawa, T. and Ueno, K., Materials Science Forum 338–342, 1101 (2000).Google Scholar
10. Yano, H., Hirao, T., Kimoto, T., Matsunami, H., Asano, K. and Sugawara, Y., Materials Science Forum 338–342, 1105 (2000).Google Scholar
11. Ghibaudo, G., Electronics Letters 24(9), 543 (1988).Google Scholar
12. Li, H., Dimitrijev, S., Harrison, H.B. and Sweatman, D., Appl. Phys. Lett. 70(15), 2028 (1997).Google Scholar
13. Chung, G.Y., Tin, C.C., Williams, J.R., McDonald, K., Ventra, M. Di, Pantelides, S.T., Feldman, L.C. and Weller, R.A., Appl. Phys. Lett. 76.,(13). 543. (1988)Google Scholar
14. Chung, G.Y., Tin, C.C., Williams, J.R., McDonald, K., Chanana, R.K., Weller, R.A., Ventra, M. Di, Pantelides, S.T., Feldman, L.C., Holland, O.W., Das, M.K. and Palmour, J.W., “Improved inversion channel mobility for 4H-SiC MOSFETs following high temperature anneals in nitric oxide”, IEEE Electron Device Lett., in press.Google Scholar
15. Chung, G.Y., Tin, C.C., Williams, J.R., McDonald, K., Weller, R.A., Ventra, M. Di, Pantelides, S.T. and Feldman, L.C., Appl. Phys. Lett. 77(22), 3601 (2000).Google Scholar
16. McDonald, K., Chanana, R.K., Weller, R.A., Feldman, L.C., Chung, G.Y., Tin, C.C. and Williams, J.R., “Nitrogen incorporation in 4H-SiC/SiO2 by NO and NH3 anneals”, submitted to Proc. Fall, 2000 Meeting of the Matls. Res. Soc.Google Scholar
17. Chung, G.Y., Tin, C.C., Won, J. H., Williams, J.R., McDonald, K., Weller, R.A., Pantelides, S.T. and Feldman, L.C., Proc. 2000 IEEE Aerospace Conf. 1, 1001 (2000).Google Scholar
18. Lipkin, L.A. and Palmour, J.W., J. Electronic Materials 25(5), 909 (1996).Google Scholar
19. Das, M.K., Cooper, J.A. and Melloch, M.R., J. Electronic Materials 27(4), 353 (1998).Google Scholar
20. Pantelides, S.T., Buczko, R., Duscher, G., Pennycook, S.J., Feldman, L.C., Ventra, M. Di, Wang, S., Kim, S., McDonald, K., Channa, R.K., Weller, R.A., Chung, G.Y., Tin, C.C., Isaacs-Smith, T. and Williams, J.R., “Bonding, defects and defect dynamics in the SiC-SiO2 system”, submitted to Proc. Fall, 2000 Meeting of the Matls. Res. Soc.Google Scholar
21. Lipkin, L.A. and Palmour, J.W., IEEE Trans. Elect. Dev. 46(3), 525 (1999).Google Scholar
22. Klein, N., Advances in Physics 21, 605 (1972).Google Scholar
23. Cooper, J.A., Purdue University, private communication.Google Scholar