Void formation in the Cu layer during thermal treatment of SiNx/Cu/Ta73Si27/SiO2/Si systems

Abstract

AbstractThe thermal stability of a SiNx passivation layer and its influence on the annealing behavior of an amorphous Ta73Si27 diffusion barrier deposited between copper and SiO2 were analyzed by X‐ray diffraction, glow discharge optical emission spectroscopy, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. During heat treatment at a temperature Tan = 500 °C, diffusion of Cu atoms out of the Cu metallization into the SiNx passivation occurs. The Cu diffusion intensifies with increasing annealing temperature and annealing time and seems to be a necessary precondition for a defect formation process observed within the Cu metallization. Depending on the chemical composition of the SiNx/Cu interface, voids in the μm‐range can be formed within the Cu film. Compared to an unpassivated sample, heat treatment leads to a reduced diffusion of Ta atoms from the barrier through the copper into the SiNx/Cu interface. The barrier crystallization process into Ta5Si3 occurring during annealing at Tan = 600 °C is principally not affected by the presence of a SiNx passivation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)