Electromigration and residual resistivity of cobalt in gold

Abstract

The electromigration of 57Co in gold is investigated by two methods (profile shift, steady‐state) at different temperatures. From this the effective charge of the gold matrix can be evaluated in good agreement with earlier results. Taking into account the vacancy flux effect the temperature dependence of the effective charge of Co in Au is given by zCoeff(T) = (1.1 ± 2.7) – (161 ± 30) μΩcm/ϱ resulting in a residual resistivity ϱd = (3.2 ± 0.6) μΩcm/at% of the thermally activated cobalt ions. Additionally performed resistivity measurements show a strong decrease of the atomic residual resistivity Δϱ (Co) with increasing temperature of cobalt atoms dissolved in gold. In the temperature range of the electromigration runs ϱd ≈ Δϱ(Co) is found. The experiments are compared to results of non‐transition metal impurities in gold.

The stress-induced escape of migrating aluminium from silicide interconnects

“…kT is the common expression for the thermal energy, and F is the electric-field force. The drift velocity v e of the migrating atoms due to the electric-field force, as contained in (1), is given by…”

“…Aluminium metallization has been widely used for interconnect lines in silicon based interconnects. The adverse effect of matter migration due to momentum exchange between the conduction electrons and the matrix or alloying atoms has been studied extensively [1][2][3][4][5]. The existence of an electromigration threshold in pure aluminium interconnects was investigated first by Blech and Herring [6,7].…”