Thermal Stability of Sputtered TiN as Metal Gate on 4H-SiC

MOS-structures were made with TiN as metal gate on 4H-SiC. The thermal stability and electrical properties of this gate was determined by CV-measurements. Comparison with Al gates showed that TiN worked well as a gate metal on 4H-SiC. The hysteresis and density of the interface states were comparable for the two gate types. The n-type samples had low leakage and a flatband voltage of a few volts, while the p-type samples had high leakage and a fiatband voltage of around -20 V. The structure showed poor characteristics after a 700°C anneal for one hour, which is probably caused by the formation of titanium silicide. The TiN films had a lower content of nitrogen than expected, which could influence the stability.