Journal of ELECTRONIC MATERIALS, Vol. 48, No. 4, 2019 https://doi.org/10.1007/s11664-019-07020-0 Ó 2019 The Author(s) Investigation of a Self-Aligned Cobalt Silicide Process for Ohmic Contacts to Silicon Carbide MATTIAS EKSTRO¨ M ,1,2 ANDREA FERRARIO ,1 and CARL-MIKAEL ZETTERLING 1 1.—Department of Electronics, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, 164 40 Kista, Sweden. 2.—e-mail:
[email protected] Previous studies showed that cobalt silicide can form ohmic contacts to p-type 6H-SiC by directly reacting cobalt with 6H-SiC. Similar results can be achieved on 4H-SiC, given the similarities between the different silicon car- bide polytypes. However, previous studies using multilayer deposition of sil- icon/cobalt on 4H-SiC gave ohmic contacts to n-type. In this study, we investigated the cobalt silicide/4H-SiC system to answer two research ques- tions. Can cobalt contacts be self-aligned to contact holes to 4H-SiC? Are the self-aligned contacts ohmic to n-type, p-type, both or neither? Using x-ray diffraction, it was found that a mixture of silicides (Co2Si and CoSi) was reliably formed at 800C using rapid thermal processing. The cobalt silicide mixture becomes ohmic to epitaxially grown n-type (1 Â 1019cmÀ3) if annealed at 1000C, while it shows rectifying properties to epitaxially grown p-type (1 Â 1019cmÀ3) for all tested anneal temperatures in the range 800–1000C. À4 2 The specific contact resistivity (qC)ton-type was 4:3 Â 10 X cm . This work opens the possibility to investigate other self-aligned contacts to silicon car- bide.