High temperature ohmic contacts to p-type SiC

Two high temperature ohmic contacts to epitaxial p-type SiC using Ti and CrB₂ will be discussed. Fabrication techniques are described along with the results of electrical and physical characterization of these contacts. Transmission line measurements show that these contacts have specific contact resistances almost as low as contacts using Al-Ti; however these contacts exhibit much more reproducibility and are more stable at elevated temperatures. Physical analysis will also show that the surface morphology of these contacts is superior to conventional Al-Ti ohmic contacts. The Ti contact is well suited for use in device fabrication processes since it requires a relatively low temperature (800°C) anneal for only one minute to form the ohmic contact. The CrB₂ on the other hand requires an 1100°C anneal for 30 minutes to form the ohmic contact, although shorter annealing times yield linear contacts with much higher contact resistances. In addition, Ti ohmic contacts to implanted p-type material will be discussed. The implanted SiC used in this work consists of Al only and Al plus C co-implanted material. The specific contact resistances obtained to implanted SiC are found to vary considerably depending on the type of implant and the post activation anneal process that is used