Substrate and annealing temperature dependent electrical resistivity of sputtered titanium nitride thin films

We have studied the electrical resistivity and the temperature coefficient of resistance (TCR) of titanium nitride (TiNx) thin films deposited by radio-frequency (RF) reactive magnetron sputtering from a high purity titanium target in a nitrogen-argon gas mixture environment with high nitrogen-to-argon ratio (20:1). The electrical resistivity and TCR are measured from room temperature to 500 degrees C for films deposited with substrate temperatures of 25 degrees C, 350 degrees C and 600 degrees C. After deposition, some films are annealed at 600 degrees C for four hours either with or without breaking the vacuum. The structural stability of the films was examined by measuring electrical resistivity from room temperature to 500 degrees C repeatedly up to four cycles. Selected films were further characterized by Rutherford backscattering, X-Ray diffraction, and Raman spectroscopy. Our results show that RF sputtered TiNx films with good electrical resistivity and temperature-stable TCR for high-temperature applications of conducive diffusion barrier and temperature sensing can be produced. We conclude that high substrate temperature, high annealing temperature, and annealing without breaking the vacuum yield optimal structural stability and electrical resistivity. High mass density is also important to prevent oxidation and degradation of electrical performance.