The Role of Organic Additives in the Localized Copper Plating: Flat, Dish, and Domed Shape Copper Bumps

Abstract

not Available.

Complementary Adsorption of Binary Levelers for Highly Uniform Cu Micropillars

“…In fine pitch, a uniform profile of Cu pillars has been critical for ensuring good electrical connections and reliability of the solder joint, since poor coplanarity of Cu pillars results in short circuits or irregular bumps in the solder bonding process . Many factors influencing Cu electrodeposition related to inorganic-based electrolyte chemistry, organic additive species, applied current density, and the bath convection environment have been reported in the context of achieving uniform pillar shape. − In particular, organic additives in the plating bath play a very important role in controlling the shape and coplanarity of deposited Cu pillars …”

“…To ensure good electrical connections and reliability of the solder joint, the coplanarity of Cu pillars is controlled through the synergistic effect of three additives: an accelerator, a suppressor, and a leveler. ,, Typically, bis-(sodium sulfopropyl)-disulfide (SPS) as an accelerator and poly­(ethylene glycol) (PEG) as a suppressor are basic additives that have been reported in multiple studies. , Levelers composed of specific chemical structures containing nitrogen could be preferentially adsorbed on the protrusions of the substrate on which the current concentrates, since the positively charged nitrogen-based functional groups of levelers are electrostatically attracted. Through such a process, the uniform surface can be achieved by the increase in overpotential on the protrusion and prevention of Cu deposition.…”