Thermally-induced stresses in thin aluminum layers grown on silicon

Abstract

Elevated-temperature X-ray diffraction (XRD) was used to evaluate residual stresses in aluminum thin films on Si(100). The films with a thickness of 2 μm were deposited by magnetron sputtering at different temperatures, and XRD measurements were carried out with the heating stage DHS 900 mounted on a Seifert 3000 PTS diffractometer. The strains were characterized always in temperature cycles from room temperature up to 450 °C with steps of 50 °C. Stress values in weakly textured thin films were calculated using the Hill model, applying temperature-dependent X-ray elastic constants of aluminum. The thin films exhibit specific temperature hysteresis of stresses depending on the deposition temperature (being from the range of 50 °C–300 °C). The results allow us to quantify contributions of intrinsic and extrinsic stresses to the total stress in the layers as well as to evaluate phenomena related to plastic yield. The comparison of the data from thin films deposited at different temperatures indicate a dependence of intrinsic stresses on the substrate temperature during deposition as well as the presence of the plastic yield in films during the cool-down after deposition