Effect of Composition on Electrical Resistivity and Secondary Electron Emission Regularities of the Tantalum Nitride Films Fabricated by Sputtering with Various Nitrogen Partial Pressure

Tantalum nitride (TaN) is a typical transition metal nitride with the characteristic of adjustable resistivity over a wide range. Low-resistance TaN even exhibits a resistivity similar to that of metals. Since the electrical resistance of the compound can influence the secondary electron emission (SEE) behaviors, this study aims to investigate the relationship between the electrical resistivity and the SEE regularities of TaN films. We prepared five groups of TaN films by varying the N₂ partial pressure during sputtering. Microstructural analysis revealed that the film thickness ranged from approximately 197 to 281 nanometers. Results obtained by X-ray photoelectron spectroscopy (XPS) indicated that the Ta:N atomic ratio of the TaN films ranged from approximately 0.53 to 0.87. Additionally, XPS results indicated the presence of non-adsorbed oxygen on the surface of the TaN films, and Further accurate XPS analysis revealed that there was TaNO compounds formed on the TaN surfaces under the influence of oxygen. Square resistivity tests show that the resistivity of the TaN films ranges from 5.67×10⁻³ to 2.43 Ω·cm. Furthermore, the lower the Ti:N atomic ratio is, the lower the electrical resistivity of the TaN film becomes. SEE coefficient (SEEC) results indicate a clear positive correlation between SEEC and electrical resistivity of the TaN films, meaning that smaller SEEC can be acquired by film with lower electrical resistivity. When the N₂ gas flow rate was 16/0 sccm, SEEC of the TaN film was the smallest/largest, with a SEEC maximum of about 1.88/2.25. The research provides valuable reference for expanding the application of TaN films in engineering scenarios involving electrical resistivity adjustment and SEE applications.