The Evolution Of Intragranular Microcracks In Metal Interconnects Due To Surface Diffusion Induced By Stressmigration And Electromigration

With the continuing decrease of feature size on the integrated circuit, the reliability of electronic device draws more and more attention. However, the microstructure evolution in interconnect might greatly affect the reliability. Based on the theoretical framework of microstructure evolution dynamics, a finite-element method is developed for simulating the microcrack evolution in interconnects. The main contents and conclusions of this paper are as follows.We derive the governing equations of the finite-element incorporating surface diffusion and evaporation-condensation induced by stressmigration and electromigration, respectively. Then we develop the finite-element programs which are based on the model of an intragranular microcrack in interconnect under stress and electric field, respectively, for simulating the microcrack evolution. Of course, the validity of this method is verified in this paper.Through the simulation under surface diffusion induced by stressmigration, the paper arrives at the conclusions: there exist critical values of the linewidth, the stress and the aspect ratio for microcrack splitting. The splitting time of the microcrack increases as the linewidth increases, while it decreases with increasing the stress or the aspect ratio.After the simulation under surface diffusion induced by electromigration, this paper gets the results that there also exist critical values of the linewidth, the electric field and the aspect ratio for microcrack splitting. The decrease of the linewidth, the increase of the electric field or the aspect ratio is beneficial to microcrack splitting and might accelerate microcrack splitting.