Bottom-up filling in Cu electroless deposition using bis-(3-sulfopropyl)-disulfide (SPS)

The effect of bis-(3-sulfopropyl)-disulfide (SPS) in Cu electroless deposition was investigated. Quartz crystal microbalance (QCM) was used to measure the current density in a complete electroless bath, and the accelerating and suppressing effect of SPS were confirmed according to its concentration. The highest acceleration effect appeared at 0.5 mg l−1 of SPS with 4.24 mA cm−2 of current density while the current density decreased to 0.485 mA cm−2 at 5.0 mg l−1 of SPS. From differences in the effect of SPS according to the concentration, Cu bottom-up filling was achieved using electroless deposition. The adsorbed sulfur compounds on the surface produced CuS, which acted as an impurity to cause an increase of the film resistivity.