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. © 2005 Elsevier Ltd. All rights reserved.