Effect of surface preparation on Ni Ohmic contact to 3C-SiC

The effect of roughness and chemical treatment of 3C-SiC film surface on Ni ohmic contact was studied in this work. 3C-SiC(1 1 1) film was grown on Si(1 1 1) in a chemical vapor deposition reactor. The 3C-SiC surface was polished using a chemical mechanical polishing (CMP) technique to get a smooth and flat surface. The polished surface was oxidized and then was etched in BHF solution to remove subsurface damages formed during the CMP process. The morphology of thus prepared silicon carbide (SiC) surfaces was investigated using SEM and AFM. Ni contact resistance to the 3C-SiC films was evaluated using linear transmission line method pattern. The formation of good ohmic contact characteristics was observed from Ni contact to all the tested SiC samples. After the CMP process, it was found that the RMS roughness of 3C-SiC surface apparently reduces and the specific contact resistance to 3C-SiC decreases as well, in proportion to the SiC surface roughness. The sacrificial oxidation and etching of the polished SiC surface abruptly decrease the contact resistance to be 3.7 x 10(-4) Omega cm(2). It was shown that the surface morphology and subsurface damage concentration of 3C-SiC films are important factors to give a great effect on the contact characteristic of the 3C-SiC films. However, it was considered that the reduction of subsurface damage concentration is essential to get better contact resistance to 3C-SiC surface. (C) 2002 Elsevier Science Ltd. All rights reserved.