Measurements of residual stresses in Al film/silicon nitride substrate microcantilever beam systems

Abstract

Microcantilevers fabricated by microelectromechanical system processes were used to study the residual stresses in the film/substrate systems. Aluminum films were deposited on silicon nitride substrates by thermal evaporation at room and elevated temperatures, and residual stresses were characterized from the deflection profiles of the Al/SiN x microcantilevers. The Al/SiN x microcantilever beam made of room-temperature-deposited Al film was found to deflect toward the substrate side, which in turn resulted in compressive residual stress in the film. In contrary, the microcantilever of Al film deposited at 105°C was found to deflect toward the side of Al film when the thickness ratio of film to substrate was greater than 0.31 and the residual film stresses were tensile. The axes with zero bending strain component and zero stresses, i.e., the bending and the neutral axes in the film/substrate system were also investigated. The results can be applied to the arm of the atomic force microscope to characterize its deflection and stresses.

Morphology and Residual Stress of Ultrathin Al Films Confined by AlN Layers

“…Instead of observing its electrical properties, it also becomes necessary to study its morphology and residual stress since they will affect the functional properties. C. C. Lin, et al who studied residual stress in Al film deposited on Si 3 N 4 substrate reported that room-temperature-deposited Al film had compressive residual stress in the film, while the residual stresses of Al film deposited at 105 °C were tensile [6]. J. H. Lee, et al who studied the mechanical properties of Al/AlN multilayer thin films, reported that measurement result on residual stress showed Al layers were subjected to compressive stress which was induced by the interface which caused overall increase of the compressive stress in the multilayer thin films [7].…”