Stress tuning in sputter-grown Cu and W films for Cu/W nanomultilayer design

Abstract

Controlling growth stresses during thin film fabrication is of paramount importance to solve reliability issues during operation of functional thin films in harsh environments. A combination of different methods for thin-film stress determination, such as in situ wafer curvature and ex situ x-ray diffraction, is usually required to reveal and tailor growth stresses in thin film systems, as well as to extract interface stress contributions in multilayered coatings. In this article, the tuning of intrinsic growth stresses in thin films of Cu and W, as grown by magnetron sputtering, was performed by varying the Ar pressure and gun power during thin-film deposition. The average growth stress in Cu and W thin films could be tuned between tensile and compressive. Next, the thus obtained knowledge on stress engineering of Cu and W single layers was applied to investigate the corresponding intrinsic stresses in Cu/W nanomultilayer coatings, for which interface stress was found to play an important role.