Analysis of Al/Ti, Al/Ni multiple and triple layer contacts to p-type 4H-SiC

This paper presents an experimental investigation into different metallisation structures aimed at reducing the contact resistance and morphology of p-type contacts to 4H-SiC. The structures are based on a combination of Al/Ni and Al/Ti layers. The lowest specific contact resistivity obtained was ba...

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Bibliographic Details
Published in:Solid-state electronics 2007-05, Vol.51 (5), p.797-801
Main Authors: Jennings, M.R., Pérez-Tomás, A., Davies, M., Walker, D., Zhu, L., Losee, P., Huang, W., Balachandran, S., Guy, O.J., Covington, J.A., Chow, T.P., Mawby, P.A.
Format: Article
Language:English
Subjects:
4H-SiC
Aluminium
Applied sciences
Electronics
Exact sciences and technology
Instruments, apparatus, components and techniques common to several branches of physics and astronomy
Interfaces
Microelectronic fabrication (materials and surfaces technology)
Nickel
Ohmic contact
p-type
Physics
Scanning probe microscopes, components and techniques
SEM
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Titanium
WDA
XRD
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Summary:This paper presents an experimental investigation into different metallisation structures aimed at reducing the contact resistance and morphology of p-type contacts to 4H-SiC. The structures are based on a combination of Al/Ni and Al/Ti layers. The lowest specific contact resistivity obtained was based on a triple layer Al/Ti/Al contact, measured at 5.0 × 10 −6 Ω cm 2. Analogously, for the triple layer contacts comprised of Al/Ni/Al, the lowest specific contact resistivity was measured at 4.9 × 10 −4 Ω cm 2. In all cases it was found that the multiple layer structures remained rectifying even after annealing. A range of physical characterisation techniques were used to investigate these different structures. X-ray diffraction (XRD) scans point to enhanced formation of silicides for triple layer contacts based on Al/Ti (Ti 3SiC 2) and Al/Ni (NiSi x ) when compared to multiple layer contacts. Scanning electron microscope (SEM) and wavelength dispersive analysis (WDA) measurements indicate that a multiple layer metallisation improves the morphology of the contact with respect to the Al spreading, which is known to be problematic during a high temperature anneal.
ISSN:0038-1101
1879-2405
DOI:10.1016/j.sse.2007.02.037