Electromigration Study of Plasma Etched Copper Lines with Copper Oxide Capping Layers

Abstract

The electromigration failure phenomena of the plasma etched copper line with a copper oxide capping layer has been studied. The copper oxide prepared by the oxygen plasma oxidation method covers the entire copper stack. The failure of this kind of structure was determined from the resistance change with the stress time. The line temperature was calculated accordingly assuming the adiabatic condition, i.e., the dissipation of Joule heat to the glass substrate and environment was negligible. The surface color of the line changes with the stress time. The composition and color of the copper oxide passivation layer were characterized and correlated to the Joule heating. The color change can be an effective reference to predict the line failure location and time. In summary, the copper oxide passivation layer can be easily formed into the self-aligned structure and the line failure process can be detected from the color change.