Interaction between electrostatic discharge and electromigration on copper interconnects for advanced CMOS technologies

The effects of electrostatic discharge (ESD), electromigration (EM) and their interdependence on Cu interconnects are studied in this work. Transmission line pulse (TLP) stress verified that metal lines fail when they are Joule heated up to a critical temperature (T/sub crit/). Failure analysis (FA) showed the gradual growth of failure sites appearing above the Cu melting point (T/sub m/=1084/spl deg/C) and leading the metal line to open failure when T/sub crit/ is reached. The pulse width dependence was investigated and the new data starting from 1.5 ns showed agreement with the theoretical model and supported the existence of non-sharp transitions between the three main regimes in the Wunch-Bell like curve (adiabatic, thermal diffusion and steady state). It was shown for the first time that the latent damage caused by TLP could degrade EM lifetime, depending on the wafer temperature and the applied current during EM stress. Lastly, to determine the current carrying capability near end of life (EOL) for the metal line, pre-EM stress followed by TLP (ESD) was performed for the first time.