Stress Migration Induced Formation of Voids / Hillocks in Tungsten Films

Stress migration behaviors in Tungsten (W) films were investigated according to morphological characteristics and residual stress analysis. Results show that stress relaxtion induced formation of voids and hillocks strips, which resembles the void / hillock pair observed in Cu film electromigration experiments. Analysis indicate that the formation of chocolate sphere shaped W hillocks is intimately related to the atoms diffusivity.