Simultaneous Formation of Ohmic Contacts on p (+)- and n (+)-4H-SiC Using a Ti/Ni Bilayer

Abstract

In this work, Ti/Ni bilayer contacts were fabricated on both p (+)- and n (+)-4H-SiC formed by ion implantation, and the effects of the Ti interlayer on the contact resistance and interfacial microstructure were studied. Adoption of a thin (10 nm) Ti interlayer resulted in specific contact resistance of 4.8 mu a"broken vertical bar cm(2) and 1.3 ma"broken vertical bar cm(2) on n (+)- and p (+)-4H-SiC, respectively, comparable to the values for contacts using only Ni. Moreover, contacts using Ti/Ni provide a flat and uniform interface between Ni2Si and SiC, whereas discontinuous, agglomerated Ni2Si islands are formed without the use of a Ti interlayer. In addition, the Ti interlayer was demonstrated to effectively dissociate the thin oxide film on SiC, which is advantageous for low-resistance, reliable ohmic contact formation. In summary, use of a Ti/Ni bilayer is a promising solution for one-step formation of ohmic contacts on both p (+)- and n (+)-4H-SiC, being especially suitable for SiC n-channel metal-oxide-semiconductor field-effect transistor (nMOSFET) fabrication.