Titanium nitride thin film for temperature sensing and its conductive mechanism in the cryogenic region

Titanium nitride (TiNx) thin films were deposited by DC magnetron sputtering on polished and oxidized silicon wafers under different N-2 flow rates, and temperature sensors based on the TiNX films were fabricated. The performance of three typical sensors were measured in the temperature range of 4.2 K-300 K, and the results indicate that TiNx thin film sensors are suitable for cryogenic temperature measurements. Furthermore, the conduction mechanism of TiNX thin film in the temperature range of 4.2 K-300 K was studied for the first time, and it can be described by an impurity conduction mechanism. Finally, the contribution of the grain and grain boundary on the film resistance and temperature coefficient of resistance was studied by AC impedance analysis, and the characterization result indicates that the impurity conduction mechanism of the TiNX thin film is dominated by the grain.