Behavior of the alloying element in Cu interconnects

We investigated the behavior of an alloying element in Cu alloy interconnects using CuAl seed from viewpoints of diffusion and reaction of aluminum. We attempted to make different type of CuAl alloy state by controlling heat treatment conditions. The results of this study elucidate the mechanism of reliability improvement and rise in resistivity by alloying element. Amount of dissolved aluminum in Cu grain affected Cu wiring resistance. EM lifetime was influenced by Al concentration at Cu/dielectric barrier interface. SIV failure rate just depended on Cu grain size, and independent on Al concentration at the Cu/dielectric barrier interface. Annealing at 250 °C in N₂/H₂ was the most preferable condition to achieve the high reliability with suppressing increase of wiring resistance in this work.