Study on the Electrical, Structural, Chemical and Optical Properties of PVD Ta(N) Films Deposited with Different N2 Flow Rates

By reactive DC magnetron sputtering from a pure Ta target onto silicon substrates, Ta(N) films were prepared with different N-2 flow rates of 0, 12, 17, 25, 38, and 58 sccm. The effects of N-2 flow rate on the electrical properties, crystal structure, elemental composition, and optical properties of Ta(N) were studied. These properties were characterized by the four-probe method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). Results show that the deposition rate decreases with an increase of N-2 flows. Furthermore, as resistivity increases, the crystal size decreases, the crystal structure transitions from beta-Ta to TaN(111), and finally becomes the N-rich phase Ta3N5(130, 040). Studying the optical properties, it is found that there are differences in the refractive index (n) and extinction coefficient (k) of Ta(N) with different thicknesses and different N-2 flow rates, depending on the crystal size and crystal phase structure.

Automated summary

The influence of different N-2 flow rates on Ta(N) films was studied, revealing that increasing N-2 flow rates decrease the deposition rate and increase resistivity. Crystal structure transitions from beta-Ta to TaN(111) and finally to the N-rich phase Ta3N5(130, 040) as N-2 flow rates increase. Optical properties, specifically refractive index and extinction coefficient of Ta(N), differ with thickness and N-2 flow rates, depending on crystal size and phase structure.