Influence of Deposition Parameters on Surface Evolution of Sputtered Tantalum Thin Films

Tantalum thin films with different thicknesses varying from 50nm to 600nm were deposited on Si substrates by radio frequency magnetron sputtering as functions of deposition temperature(Ts) and bias voltage(Ub). Surface roughness and its dynamic evolution behavior were quantitatively investigated by using atomic force microscopy(AFM). With increasing Ts from 300K to 600K, surface roughness Rrms and dynamic exponent β decreases gradually. With the increase of Ub from 0V to -150V, Rrms and β first decrease and then increase. The dependence of Ts and Ub on the film surface evolution has been discussed in terms of surface diffusion, mound growth, and ion impinging effect.