FEA study on the TSV copper filling influenced by the additives and electroplating process

Through-Silicon Via (TSV) is a key technology of three-dimensional (3D) integration. However, Voids are usually found in the Cu filling process of TSV, and lead to lower reliability. Additives and optimized filling process are used to solve this problem. However, the comprehensive analysis of these affecting parameter needs many experiments and cost much time. Thus, the finite element analysis (FEA) for the mass transferring of electroplating is carried out by the COMSOL software in the work. Different inhibitor concentrations in filling process are first studied and the most suitable density of 64 mol/m² is obtained. However, high inhibitor concentration will lead to much lower plating speed. Thus, the effect of filling process such as current density and plating bath flow velocity on the voids are investigated under the optimized concentrations above. The best filling quality is obtained at the inhibitor concentration of 64 mol/m², current density of 1.4 ASD and the bath stirring velocity of 0.4 m/s. The underlying growth mechanism of these influencing factors are also analyzed and revealed.