Wettability of electrodeposited copper films and correlation with morphology and surface chemistry

In this study, different forms of copper films were electrodeposited (ED) on silicon wafer, copper and brass foils. The effect of monocrystalline Si(111) surface cleaning method and electrodeposition conditions and regimes (frequency in the pulsating current (PC) regime, an addition of additives in electrolyte for the constant galvanostatic (DC) regime, and thickness) on surface morphology and wettability of copper films was investigated. Optical microscopy equipped with high-resolution camera, scanning electron microscopy (SEM) and an atomic force microscopy (AFM) were used for thin film characterization and to evaluate wettability of copper films. The sessile drop method was used for the measurement of water contact angle. According to the obtained results, choice of electrolyte used in ED greatly affects wettability of copper films. It was also shown that copper films electrodeposited from basic sulfate electrolyte with varying current regimes frequencies, thicknesses, and cathode types have opposite trends between roughness parameter values and the water contact angle value. Structural-morphological changes of a film or bulk solid surface are key parameters in determining wettability properties and the analysis of the wetting angle oscillations, but not the only one.