Additional control of bombardment by deep oscillation magnetron sputtering: Effect on the microstructure and topography of Cr thin films

Abstract

In magnetron sputtering additional control of the bombarding species can be obtained by ionizing the sputtered flux as in high power impulse magnetron sputtering (HIPIMS). The main objective of this work is to evaluate the effectiveness of the additional control of bombardment in Deep Oscillations Magnetron Sputtering (DOMS), a variant of HIPIMS. For this purpose, Cr thin films were deposited by d. c. Magnetron Sputtering (DCMS), with and without substrate biasing, and by DOMS between 0.2 and 1.0Pa. The microstructure and topography of the deposited films were characterized by SEM and AFM. It was found that the shadowing effect is the dominant film formation mechanism in DCMS and that it is stronger along the substrate rotation direction, resulting in anisotropic surfaces. The DOMS process allows to overcome the shadowing effect by decreasing the strength of the shadowing effect rather than by decreasing its effectiveness, as is usually the case in magnetron sputtering when using high energetic bombardment. It also allows to minimize the effect of geometrical asymmetries of the deposition system in the films properties, which is of paramount technological importance as large substrate batches with several rotation degrees are usually processed in industrial conditions.