Interface study of thermally driven chemical kinetics involved in Ti/Si3N4 based metal-substrate assembly by X-ray photoelectron spectroscopy

Abstract: Diffusion mediated interaction in metal-substrate assembly during high temperature annealing leads to possible formation of new composite materials. Here, sputtered grown Ti films on Si3N4/Si substrate has been reported to produce titanium nitride and silicide based binary composites while undergoing high vacuum annealing process at temperatures 650{\deg}C and above. Diffusion of thermally decomposed Si and N atoms from Si3N4 and their subsequent chemical reaction with Ti have been probed by X-ray photo electron spectroscopy. For annealing at 800{\deg}C and above, most of the Si atoms show preferences to stay in elemental form rather than developing silicide phase with Ti. Whereas at lower annealing temperature, silicide becomes the dominant phase for decomposed Si atoms. However, N atoms react promptly with Ti and form TiN which appears as the majority phase for each of the studied annealing temperature. Further, the nitride and silicide phases across the films have been compared quantitatively for various annealing temperature and the maximum silicide formation is observed for the sample annealed at 780{\deg}C. Finally, the thermally anchored metal-substrate interaction mechanism can be exploited to fabricate disordered superconducting TiN films where TiSi2 and Si can be used to tune the level of disorder by altering the annealing temperature.