Yield Stress in Single Crystal and Polycrystalline Al Films

Abstract

The stresses in single crystal and polycrystalline Al films were determined by wafer curvature measurements during temperature cycling. Both elastic and plastic behavior was observed. The single crystal film exhibited anisotropic yield stresses indicating that dislocation glide is the dominant deformation mechanism. The polycrystalline film exhibited similar behavior, although without the anisotropy, indicating that it too deforms by dislocation glide. Unlike the single crystal film, the yield stress in the polycrystalline film varied depending on thermal and deformation history. These effects are attributed to the presence of grains and grain boundaries in the polycrystalline film.