Effect of Grain Boundary/Interface Network on Fracture Due to Atom Migration Induced by Stress in an LSI Conductor

Abstract

Atom migration induced stress in an LSI conductor is analyzed on the basis of diffusion along grain boundary (GB) and interface. The focus is put on the network of GB and interface, which strongly affect the atom flux near the cavity. The numerical analyses are conducted for the conductors with polycrystalline network, bamboo structure and near-bamboo structure. Results obtained are as follows. (i) In a conductor with polycrystalline, the atom migration along GBs is activated near a cavity while there is little flow in a conductor without the cavity. This is due to the stress distribution, which is introduced by the cavity. The cavity grows by the atom transport. (ii) Interface difiusion between the conductor and the surrounded passivation activates the atom migration along GBs inside of a conductor for all simulations. This implies that the cavity grows under the interaction between GB diffusion and interface one. (iii) Growth rate of a cavity in a conductor with the near-bamboo structure, which contains a few triple junctions of GB, is faster than that in a one with the bamboo structure. This shortens the life of conductor, which is correspondent with experimental observation reported before.