Ni Si Alloy/4H-SiC Reaction and Silicide Formation under Excimer Laser Annealing for Ohmic Contact
Publication date: 18 Mag 2026
Laser annealing is considered an enabling process for a new generation of SiC power devices, since it allows the formation of ohmic contacts on very thin wafers, significantly reducing their total ON resistance. Ni silicide and Ti silicide ohmic contacts have been widely investigated and reported in literature, exploring in detail the role of laser features, metal thickness and thinning process. Nevertheless, adding a small amount of Si to the contact layer could represent an opportunity to increase process options. In this work, a NiSi alloy has been used as a contact metal to study the role of the addition of Si to Ni in the reaction process under UV laser irradiation. Morphological and structural properties of the reacted layers have been investigated by means of Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) analyses. The electrical characterization of reacted contacts has been performed by measuring their Sheet Resistance (R s ) by Four Point Probe (FPP) method and, at device level, by measuring the forward voltage drop (V f ) of Schottky Barrier Diodes (SBDs) fabricated on 150 mm-diameter 4H-SiC wafers. Furthermore, a comparison has been made between Ni and NiSi alloy under the same irradiation conditions. It has been found that adding Si to Ni in the contact metal layer moves the silicide reaction forward, driving the strong relationship observed between structural, morphological and electrical properties of the reacted contacts.