Diffusional Creep Driven Deformantion Mechanism of Cu Through-Silicon Via

Through-silicon via is facilitating us designing 3D chip for next generation electronic application. But miniaturization of electronic packaging introduced serious reliability issues, e.g., warpage of TSV, interfacial sliding, delamination of Cu/ low-k dielectric in BEOL, growth of voids, etc under electromigration, thermal cycling, and thermal cycling. My goal is to experimental observation of the failure phenomena due to electromigration and thermal cycling and understanding the underlying physics and mechanics of these using finite element modeling.


Numerical Modeling of Interface Elasticity Problems for Orthotropic Structures

Interface, either as inclusions or layer, between two or more structural materials is being considered as one of the most vulnerable regions of failure. Mismatch of properties across the interface gives rise to the jumps in elastic field parameters. Hence, predicting the stress near the singularity regions is given utmost importance in the field of structural mechanics. A new finite difference computational scheme, based on displacement potential approach to elasticity, has been developed in order to predict the elastic field in the structure. Continuity of displacements and tractions in conjunction with the uniqueness of displacement potentials and their slopes along the interface were used to modify the regular finite difference form of displacement potential governing equation. Stencils of the boundary conditions are also modified for interfaces penetrating physical boundaries.

Calculation of stress and displacement revealed some important results for multi-material interfaces and inclusion in structures. Effect of materials and geometric proportion of constituent materials were also studied thoroughly to establish a new structural design guide for future applications.