Temperature gradient impact on electromigration failure in VLSI metallization

A novel W-Ti self-heating structure was proposed which can generalize a temperature gradient and constant temperature along the metal stripe and can determine the failure location by electrical measurement. The effectiveness of this design is confirmed by different experiments. A metal line resistance method was used to determine the temperature distribution on the metal line. A series of electromigration tests were performed at positive and negative temperature gradients. The results indicate that the negative temperature gradient greatly improved the mean time to failure (MTF) of electromigration, changed the failure location distribution and caused a new tendency of resistance change which the authors dubbed the "new balance phase".