Electromigration and the Current Density Dependence

The empirical expression used to predict metallization resistance to electromigration failure involves the current density raised to the power n. A value for n of 1.5 was obtained from stressing unpassivated Al 1% Si metallization test structures over a range of current densities from 0.5 to 2.5 MA/cm2. The steps taken to ensure an accurate estimate of the metallization stress conditions of temperature and current density to obtain this value are described in detail.