Investigation of the Interaction Effect Between the Microstructure Evolution and the Thermo-Mechanical Behavior of Cu-Filled Through Silicon Via

With the development of Cu-filled through silicon via (TSV) technology, more concerns should be given to the physical and mechanical behavior of the Cu filler in TSV, in particular, there is an intricate interaction between the grain morphology evolution and the thermo-mechanical behavior of the Cu filler, which can greatly affect mechanical properties and reliability of the TSV structure in integrated circuits due to the smaller size of TSV. In this work, a phase field model is employed to investigate the grain growth and thermo-mechanical behavior, and clarify their interaction effect in the Cu-filled TSV. It is found that the average stress in the TSV decreases with the grain growth in the Cu filler, due to the orientation dependence of mechanical properties of Cu grains. The stress drives the preferential growth of Cu grains with low Young's modulus, leading to a higher protrusion of Cu filler than that without considering the thermal stress effect on grain growth.