A study of bottom-up electroplated copper filling by the potential difference between two rotating speeds of a working electrode

Abstract

In order to achieve a bottom-up plated copper filling with a minimal surface thickness, an additive system containing a pluronic triblock copolymers, ethylene oxide terminal blocks termed EPE as a suppressor, bis(3-sulfopropyl) disulfide (SPS) as accelerator, Janus Green B (JGB) as leveler, and Cl− was used to investigated bottom-up filling by galvanostatic measurements method and cross-sectional OM observation. The EPE-8000 not only was a stronger inhibition for electrodeposition copper reaction, but also had a stronger forced convection with JGB and Cl− in copper electroplating solution than PEG-8000 for copper deposition. The potential difference obtained from two different rotating speeds of a copper working electrode by galvanostatic measurements reached positive 20mV with an addition of the EPE-8000 and was much higher than that with an addition of PEG-8000 (about 12mV), which led to a high filling performance with a minimal surface copper thickness. The effects of additives SPS, JGB, and Cl− on the potential difference and bottom-up filling behavior were investigated in detail. With an addition of EPE-8000, the filling performance of the plating copper solution was enhanced, the surface thickness of deposited copper film was reduced, but also the operation windows of four additives were widened extensively.