Real-time observation of Cu electroless deposition: Effect of EDTA on removing of Cu oxide and adsorption of formaldehyde

During Cu electroless deposition (Cu ELD), the effect of ethylenediaminetetraacetic acid (EDTA) on the adsorption of formaldehyde on pre-oxidized Cu surface was investigated in real time by open-circuit potential measurement assisted by quartz crystal microbalance. It was found that formaldehyde alone rarely adsorbed on the oxidized Cu surface. However, in the presence of EDTA, the adsorption of formaldehyde occurred as EDTA removed the Cu oxide from the surface. On an oxidized Cu surface, the oxide removal by EDTA occurred predominantly in the initial stages of ELD. Subsequently, deposition began when formaldehyde was able to be adsorbed on the Cu surface. The process was also characterized using sheet resistance measurement and X-ray photoelectron spectroscopy. EDTA facilitated the Cu ELD process even in the presence of Cu oxide at the surface.