Complementary Studies of Aluminum Thin Films: Resistivity and Real Structure

The article presents the results of comprehensive studies on the temperature dependence of the electrical resistance of thin magnetron Al films, examining their structural characteristics, including morphology, surface roughness, microstructure, and density. To establish a fundamental relationship between the specific resistance and structural features of the films, they were deposited on standard Si(111) substrates in a two-stage growth mode with the formation of homobuffer layers in the temperature range from 293 to 800 K. Structural characterization of the samples was performed using scanning force and electron microscopy, X-ray diffractometry and X-ray reflectometry. It is demonstrated that the value and temperature dependence of the specific resistance of aluminium films can be altered by varying the growth conditions of the homobuffer layer, enabling the deposition of films with different density profiles across their thickness. The magnetron 120-nm aluminium film on a 700 K homobuffer layer with a constant density of 2.66 g/cm is found to have a specific resistance of ρ = 2.69 μΩ·cm and T = 1.22 K. Al films with variable density exhibited a residual resistivity of 30 μΩ·cm. The primary contribution to the resistance of such films is made by intergranular regions with lower density. These regions are reliably detected by the X-ray reflectometry technique.