Barrier Layer Morphological Stability and Adhesion to Porous LOW-κ Dielectrics

Abstract

Two particularly important reliability issues facing the integration of low- κ dielectric films are the fracture energy of the barrier-dielectric interface and the barrier layer integrity during processing. We have noticed that the compressive stresses in the barrier layers on low- κ dielectrics lead to spontaneous delamination and formation of telephone-cord like morphologies. These morphologies allow the measurement of fracture energy and are advantageous over artificially contrived features to yield realistic debonding parameters. The fracture energy of common barrier films, TaN and Ta, was determined using this method for varying porosity nanoporous silica and MSQ. Detailed characterization of the telephone cord morphology using a combination of Optical Microscopy, SEM and Profilometry was done. The fracture energy for Ta on different low-κ dielectrics was evaluated using a 1-D model for straight buckles. The kinetic coefficient of buckling was also evaluated.