As conventional 2D scaling of microelectronic devices shows limitations, 3D chip stacking is clearly identified as a solution for performance gain at lower cost in applications such as image sensors, stacked memories, high performance processor-memory assemblies and advanced system in package (SiP) leading to heterogeneous integration. In that respect, Through Silicon Via (TSV) technology is one on the key process step to enable new interconnection schemes. Metallization of TSV structures is currently attracting a lot of attention due to the multiple technical challenges associated with this new technology [K. Kondo, T. Yonezawa, D. Mikami, T. Okubo, Y. Taguchi, K. Takahashi, D.P. Barkey, J. Electrochem. Soc. 152 (2005) H173; O. Lühn, C. Van Hoof, W. Ruythooren, J.-P. Celis, Electrochim. Acta 2007, doi:10.1016/j.electacta.2008.04.002]. Copper electrodeposition has soon been identified as a technique of choice for such connections based on the widely acceptance of copper as wiring material for submicronic interconnections [T.P. Moffat, D. Wheeler, M. Edelstein, D. Josell, IBM J. Res. Dev. 49 (2005) 19; J. Reid, Jpn. J. Appl. Phys. – Part 1 40 (2001) 2650]. However, the specificity of TSV structures, combining both high aspect-ratios and via depth ranging from tenth to several hundred microns, implies the development of new deposition methodologies and chemistries. In particular, the mode of action of organic additives (accelerator, suppressor and leveller) promoting the so-called “bottom-up filling” can be greatly affected by mass transportation and convection effects associated with large volumes TSV vias compared to Damascene structures. Here we present a study aiming at optimizing the accelerator concentration in the plating bath in order to maximise the copper deposition rate while preserving a reduced overburden at the via mouth. Cyclic voltammetry data correlated with filling experiments conducted on 150 μm vias with an aspect-ratio of 2, will be presented in order to better understand the relationship between chemical composition and process efficiency in such TSV structures.