Strong Convection-Dependent Adsorption of Phenothiazine Skeleton Levelers and Their Application in Copper Electroplating

The design and synthesis of high-performance levelers remain a major challenge to date. Herein, a series of phenothiazine (PTZ) derivatives were designed and synthesized, and they had a butterfly conformation, and their adsorption capacities were easier to modulate. To check out the inhibition capabilities among these eight PTZ derivatives, electrochemical measurements and theoretical calculations were carried out, and PTZ-8 indicated the strongest inhibition capabilities among these PTZ derivatives. Besides, galvanostatic measurements were also carried out to evaluate the overall performance of the levelers. The results showed that PTZ-8 had a potential oscillation, but PTZ-6 had strong convection-dependent adsorption. Due to the potential oscillation of PTZ-8, PTZ-6 as the representative leveler was selected for through-hole electrodeposition. In addition, field-emission scanning electron microscope images and X-ray diffraction results displayed the surface morphology, which indicated that the addition of PTZ-6 could lead to a fine copper deposit and cause the preferential orientations of copper deposits to change from [220] to [111]. This study might lay the foundation for the design of high-performance levelers.