Vapor- and impurity-controlled growth regimes during deposition of thin noble metal films on weakly-interacting substrates

We study the effect of impurities on the morphological evolution of thin silver (Ag) and copper (Cu) films deposited by direct current and high-power impulse magnetron sputtering on weakly-interacting silicon dioxide and amorphous carbon substrates. We systematically vary the ratio of impurity-to-metal particle flux J imp J metal arriving at the substrate in the range ∼ 10 − 4 − 10 and assess the character of film morphological evolution and the overall growth dynamics by means of real-time in-situ diagnostic tools and ex-situ analyses. We find that both thin-film materials exhibit a three-dimensional morphological evolution, which for the case of Ag is governed by the effect of metal vapor flux magnitude on the dynamic competition among island nucleation, growth, and coalescence ( vapor-controlled growth regime ). At all deposition conditions, small amounts (of the order of 1 at . % ) of impurities (comprising oxygen, carbon, and hydrogen) are incorporated in the Ag films, while an increase of J imp J metal suppresses three-dimensional growth for layers deposited on silicon dioxide. Cu exhibits a similar ( vis-à-vis Ag) behavior with respect to the overall morphology and impurity incorporation for J imp J metal below a critical value of ∼ 1 . For J imp J metal above ∼ 1 , the impurity content in the Cu layers increases sharply (reaching ∼ 10 at . % for J imp J metal ∼ 10 ) and film morphological evolution is seemingly determined by the effect of impurities on the fundamental structure-forming process of island nucleation, grain growth, and crystal growth ( impurity-controlled growth regime ). • Ag and Cu films exhibit 3D morphological evolution on SiO 2 and a-C substrates. • Control of deposition rate and base pressure allows tuning impurity-to-metal flux ratio during film growth. • Ag morphological evolution is controlled by the magnitude of metal vapor flux. • Impurities largely function as surfactant during Ag film growth. • Cu morphological evolution is controlled by the degree of impurity incorporation in the film.