Microscopic mapping of specific contact resistances and long-term reliability tests on 4H-silicon carbide using sputtered titanium tungsten contacts for high temperature device applications

Abstract

We report on the microscopic mapping of specific contact resistances (ρc) and long-term reliability tests using sputtered titanium tungsten (TiW) ohmic contacts to highly doped n-type epilayers of 4H-silicon carbide. The TiW ohmic contacts showed good uniformity with low contact resistivity of 3.3×10−5 Ω cm2. Microscopic mapping of the ρc showed that the ρc had a distribution that decreased from the center to the edge of the wafer. This distribution of the ρc is caused by variation of the doping concentration of the wafer. Sacrificial oxidation at high temperature partially recovered inductively coupled plasma etch damage. TiW contacts with platinum and gold capping layers have stable specific contact resistance at 500 and 600 °C in a vacuum chamber for 308 h.