How Pore Size and Surface Roughness Affect Diffusion Barrier Continuity on Porous Low-k Films

The structural features that affect continuity of ultrathin diffusion barriers on porous low-dielectric-constant ~k! thin films has been investigated. The dimensions of interconnected nanopores in a series of Dow Corning XLK films are found to increase as the dielectric constant becomes smaller. The minimum thickness required for tantalum ~Ta! to form a continuous barrier layer is affected by the pore size and surface roughness of the porous low-k films according to positronium annihilation lifetime spectroscopy analysis. The films with large pores require thick barrier layers to form effective diffusion barriers. The surface roughness of the porous films as observed by atomic force microscopy has a significant influence on the continuity of diffusion barriers. © 2003 The Electrochemical Society. @DOI: 10.1149/1.1566415# All rights reserved.