Thermally stable low ohmic contacts to p-type 6H-SiC using cobalt silicides

Cobalt silicide (CoSi2) ohmic contacts possessing low specific contact resistivity (rho(c) < 4.0 +/- 0.7 x 10(-6) Omega cm(2)) to p-type 6H-SiC are reported. The contacts were fabricated through sequential electron-beam evaporation of Co and Si layers forming a Si/Co/SiC structure, followed by a two-step vacuum annealing process at 500 and 900 degrees C, respectively. Specific contact resistivities were extracted from transmission line model (TLM) structures at temperatures ranging from 22 to 200 degrees C. rho(c) is investigated as a function of current density, temperature and ageing in a vacuum furnace at 1100 degrees C. Furthermore, comparison with a Co/SiC contact structure subjected to an identical annealing process revealed higher rho(c) and a modified sheet resistance requiring a different method of contact parameter extraction. Copyright (C) 1996 Published by Elsevier Science Ltd