1-Dodecyl-2-methyl-3-benzylimidazolium chloride as a novel leveler: Towards simultaneously both the microvia void-free filling and through hole conformal thickening

Abstract

In this work, an organic additive, 1-Dodecyl-2-methyl-3-benzylimidazolium chloride (DMBI), is explored as a novel leveler with excellent property in simultaneous microvia and through hole copper metallization. Studies of galvanostatic measurements (GM) and cyclic voltammetry stripping (CVS) demonstrate that DMBI exhibits the necessary fundamental leveler’s characteristics of convection-dependent adsorption, and the stronger inhibition effect on copper ions electroreduction at a higher electrode rotating rate. Moreover, the combination of DMBI and SPS behaves a stronger convection diffusion effect than that of DMBI and PEG. In situ attenuated total reflectance-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) spectroscopic analysis illustrates that DMBI affects the electroreduction of copper ions by competing with bis-(sodium sulfopropyl) disulfide (SPS), and polyethylene glycol (PEG) can slightly weaken the decrease of DMBI adsorption cross section on copper surface. Based on the outstanding characteristics of DMBI as a novel leveler, we develop an advanced DMBI-based formula for Cu electronic plating, and achieve the microvia void-free filling and through hole conformal thickening simultaneously in a printed circuit board (PCB).