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Investigation of electromigration induced hillock and edge void dynamics on the interconnect surface by computer simulation

Çelik, Aytaç
The Electromigration-induced failure of metallic interconnects is a complicated process, which involves flux divergence, vacancy and atom accumulation with or without compositional variations, void and hillocks nucleation, growth and shape changes. Hillocks and surface void dynamics in connection with the critical morphological evaluation have been investigated in order to understand the conditions under which premature failure of metallic thin interconnects occur. In this thesis, an interconnect is idealized as a two dimensional electrically conducting strip which contains gaussian form hillock or edge void. Indirect boundary element is used to predict the evolution of the surface after the applied electric field. Computer simulation results show that the surface crystal structure of is extremely important in the determination of the life time of thin film single crystal interconnect lines. Under the applied electrostatic field not only the degree of rotational symmetry (parameter, m) but also the orientation of the surface plane play dominant role in the development of the surface topology and the formation of the fatal EM induced voids. The degree of anisotropy in the surface diffusion coefficient, and the intensity of the electron wind parameter may have great influence on the evolution regime actually taking place on the surfaces and at sidewalls of the interconnects.