The Evolution Of Intragranular And Transgranular Microcracks Induced By Electromigration And Stress Migration

At present, the integrated circuits are applied to all walks of life, such as aerospace, medical andhealth, and weaponry, etc. The reliability of the metal thin film interconnect wires in integratedcircuits has became a hot research. In this paper, based on the free energy variation principle of themicrostructure, the evolution of intragranular and transgranular microcracks induced byelectromigration and stress migration are simulated by finite element method.First, based on the classical theory and the weak statement of surface diffusion andevaporation-condensation, the evolution equations for finite element method under the stress field areestablished. The finite element program is coded to simulate the evolution of the two-dimensionalmicrocrack. The reliability and accuracy of the program is also verified.Then, a model of intragranular microcrack within the metal materials is presented under externalloads and internal pressure. The effects of the aspect ratio, the internal pressure q, and themagnitude of the stress0on the microcrack evolution are discussed in detail.Finally, based on the theory of surface diffusion and grain boundary diffusion induced byelectromigration and stress migration, a simplified model of transgranular microcrack undermulti-physical fields is established. A finite element scheme is implemented and a program isdeveloped for simulating the evolution of two-dimensional transgranular microcracks under stressfield and electric field. The effect of two diffusion coefficient ratio, the magnitude and the state of thestress, electric field and the initial aspect ratio on the microcrack evolution are investigated detailedlyin the dissertation.