Experimental and Theoretical Study of the New Leveler Basic Blue 1 during Copper Superconformal Growth.

A novel chlorinated functional group-modified triphenylmethane derivative leveler BB1 is used to achieve superconformal electrodeposition in microvias. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are performed to study the suppressing effect of BB1, while the convection-dependent adsorption of BB1 on the copper surface is analyzed by galvanostatic measurement, and a BB1 concentration window between 100 and 200 mg/L is beneficial for superfilling. The interactions among BB1, bis-(sodium sulfopropyl) disulfide (SPS), and poly(ethylene glycol) (PEG) are also investigated. Density functional theory (DFT) calculation and Raman spectroscopy are coupled to study the suppression mechanism and synergistic suppression mechanism, namely, the adsorption effect between BB1 and copper substrate, as well as the coordination effect between the modified chlorinated functional group and Cu, is proposed. The copper layer becomes smoother and more compact with an increase in BB1 concentration, according to scanning electron microscopy (SEM) and atomic force microscopy (AFM), while X-ray diffraction (XRD) analysis shows that the introduction of BB1 is conducive to the formation of the copper (220) plane. Besides, the solution wettability is boosted by BB1. A copper interconnecting layer with high quality is achieved with 150 mg/L BB1, while the surface deposition thickness (SDT) is about 34 μm and filling percentages (FPs) for microvias with diameters of 100, 125, and 150 μm are 81.34, 82.72, and 81.39%, respectively.