Materials Science Forum, Vol.457-460, 833-836, 2004
Comparison of different surface pre-treatments to n-type 4H-SiC and their effect on the specific contact resistance of Ni ohmic contacts
SiC power devices are becoming more common in the power electronics industry. Paramount to the development of good quality power devices is the ability to create low resistive device contacts. Many metals have been experimented with in an effort to fabricate such contacts although Ni has been the metal of choice in recent years. In addition to the choice of contact metal, the pre-treatment of the semiconductor surface and the annealing of the contact play a vital role in achieving low resistive contacts. In the most instances, a complicated acid treatment and etching process is used to provide a clean surface prior to metal deposition. The contact is subsequently annealed at high temperatures (1000degreesC) in either an inert gas ambient or under high vacuum conditions to produce an ohmic contact. This work details the fabrication of Ni ohmic contacts to n-type 4H-SiC using different surface preparation techniques. Specific contact resistances, obtained from Circular Transfer Length Measurements (CTLM), of contacts fabricated using a standard RCA are compared to results for the different surface pre-treatments.