3D CHARACTERIZATION OF A W TIN/TI/SI CONTACT STRUCTURE USING MULSAM/

The W/TiN/Ti/Si contact structures needed for ultra-large-scale integr ated circuits have been studied using cross-sectional transmission ele ctron microscopy (TEM) and multi-spectral Auger electron microscopy, A ccess to the Ti/Si interface for chemical characterization using SEM, Anger and electron energy-loss imaging and spectroscopy has been achie ved by using a novel method of bevelled polishing of the silicon subst rate material, Cross-sectional TEM was used to calibrate the depth sca le in the MULSAM image sets, so allowing measurements of the thickness es of various interfacial layers and the penetration of the ohmic cont acts into the silicon. The TiN layer, providing adhesion of the tungst en as well as acting as a diffusion barrier, appears to have a domed s hape, which penetrates the tungsten overlayer to a greater extent in t he contact centres. The results of this work, combined with earlier, r elated, studies, enable a three-dimensional characterization of the bo ttom and sidewall structures in these contacts. (C) 1998 John Wiley & Sons, Ltd.