Effect of Chloride on Microstructure in Cu Filled Microscale Through Silicon Vias.

The microstructure of copper filled through silicon vias deposited in a CuSO4 + H2SO4 electrolyte containing micromolar concentrations of deposition rate suppressing poloxamine and chloride additives is explored using electron backscatter diffraction. Regions with distinct microstructures are observed in the vias, including conformal deposition and seam formation localized adjacent to the bottom that can transition to bottom-up filling higher in the features. The presence and extent of each microstructure depends on applied potential as well as additive concentration. Deposition in the presence of higher chloride concentration yields a strong (110) growth texture in regions where bottom-up filling exhibits a horizontal growth front profile while (110) textured or untextured growth is observed for different conditions where upward growth proceeds with a v-notch profile.