Texture inheritance in Al(Cu) interconnect materials

Abstract

Deposition surface morphology plays a major role in governing the texture within sputter deposited Al (0.5% wt., Cu) films. The presence of a thin Ti barrier layer provides an epitaxial template for Al(Cu) atoms to grow. However, the topography of the surface on which the Ti is deposited also influences Al(Cu) film texture. Through a combination of x-ray pole figure analysis and scanning electron microscopy, we observed that the behavior of (111) texture of Al(Cu) films deposited on Ti is dictated by the underlying surface roughness. A quantitative link between the offset in maximum Al (111) texture from the substrate normal and the average surface orientation of the deposition surface has been established. Information from atomic force microscope scans of the underlying surface has been used to construct a surface offset distribution (SOD), which contains the distribution of local orientations within a surface. Above a threshold roughness of the deposition surface, the SOD maxima correspond to the observed offset Al (111) texture in Al(Cu)/Ti films deoosited on a variety of interlevel dielectric layers. © 2001 American Institute of Physics.