Influence of underlayer and encapsulation process on texture in polycrystalline silver thin films

The texture in polycrystalline Ag thin films prepared by e-beam evaporation has been characterized by an x-ray diffraction technique as a function of underlayers and encapsulation temperatures. The Ag films deposited on Ti layers showed a strong <111> fiber texture with a fiber axis parallel to the film normal, whereas an almost random orientation was observed in the Ag films on Cr layers. This underlayer dependence of texture is associated with the lattice match between Ag and underlayer metal. In addition to <111> texture, the Ag films on Ti also exhibited a <511> texture component, which is the result of twinning of <111>-oriented grains. After the encapsulation process, the <111> texture in the Ag films on Ti was significantly improved, as evidenced by an increased (111) diffraction intensity and a slightly narrower space distribution of the texture along the fiber axis. The highly textured Ag films are expected to exhibit an improved electromigration resistance.