Fatty Acid Quaternary Ammonium Surfactants Based on Renewable Resources as a Leveler for Copper Electroplating

et al. 2022

ACS Omega

Highly uniform Cu micropillars were electrodeposited on a Cu seed layer in a micropatterned photoresist in the presence of binary levelers containing pyrrolidine and pyridine functional groups. The adsorption behaviors of binary levelers, i.e., 3hydroxy-6-(tert-butyl)pyridine and pyridinium tribromide in an electroplating bath were investigated by chronopotentiometry with sequential injection of levelers and linear sweep voltammetry with a rotating disk electrode. From electrochemical analysis, pyridinium tribromide composed of a positively charged pyridine ring was strongly adsorbed on the Cu seed surface, relative to 3hydroxy-6-(tert-butyl)pyridine. Additional microscopy, surface roughness, and nitrogen concentration analyses revealed that the binary levelers were preferentially adsorbed on the center and the edge region of the Cu seed, resulting in a uniform Cu pillar profile. The possible mechanism of highly uniform Cu pillar deposition was discussed in terms of the adsorption behaviors of the levelers dependent on their molecular structures.

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Complementary Adsorption of Binary Levelers for Highly Uniform Cu Micropillars

Kim

et al. 2022

ACS Omega

“…The throwing power ( TP ), a crucial indicator to characterize the thickness uniformity of the copper coating in the THs, was obtained according to the cross‐section images [46–48] . The throwing power ( TP ) value was calculated by the Equation (5).…”

Section: Methodsmentioning

confidence: 99%

“…The throwing power (TP), a crucial indicator to characterize the thickness uniformity of the copper coating in the THs, was obtained according to the cross-section images. [46][47][48] The throwing power (TP) value was calculated by the Equation ( 5). The H a , H b , H c , H d , H e and H f in the formula were the electroplated copper coating thickness presented in the Figure 8.…”

Section: Electroplating Experimentsmentioning

confidence: 99%

Toward Preeminent Throwing Power from a Novel Alkaline Copper Electronic Electroplating Bath with Composite Coordination Agents

Yang

et al. 2022

ChemElectroChem

In this work, an electronic copper electroplating bath with low copper ion concentration and preeminent throwing power in through hole (TH) thickening of the printed circuit board (PCB) was successfully developed. Based upon the weak alkaline bath containing the composite complexants of citrate (Cit) and ethylenediamine (En), their synergistic effects on the preeminent bath throwing power were carefully investigated and theoretically proved. The UV‐vis spectroscopy results illustrated that En exhibited a stronger coordination ability with Cu (II) ion than citrate, and the stoichiometric coordination ratio between En and Cu (II) ion was 2 : 1. The linear sweep voltammetry (LSV) results showed that the electro‐reduction peak potential of Cit−Cu coordination ion was −0.55 V (vs. Hg/HgO), whereas that of En−Cu ion was at a more negative potential of −0.82 V. The in situ Fourier transform infrared (FTIR) spectroscopy revealed that the adsorptions of the Cit−Cu and En−Cu coordination ions were potential dependent on the copper electrode. The Cit−Cu coordination ion was easily adsorbed at the interior sites of through holes with lower over‐potential to promote the growth of copper coating. Moreover, the En−Cu coordination ion adsorbed preferably on the surface and the edge of through hole for its higher electro‐reduction overpotential, to hinder the germinating of copper nuclear. The cross‐section observation of optical microscope proved that the throwing power of novel copper electroplating bath behaved surpassingly, up to 105.8 %.

“…Copper is chosen as the filling metal on account of its high electromigration resistance and an excellent thermal (401 W·m –1 K –1 ) and electrical conductivity (1.67 μΩ·cm). Acidic sulfate copper electronic electroplating is the most popular process to realize void-free filling. − …”

Section: Introductionmentioning

confidence: 99%

Novel, Simple, and Green Citrate-Based Copper Electronic Electroplating Bath in Microvia Void-Free Filling for Printed Circuit Board Application

ACS Sustainable Chem. Eng.

Wang

et al. 2022

In this work, a novel, simple, and green citrate-based copper electronic electroplating bath with the characteristics of weak corrosion, low copper ion concentration, and simple composition is developed in microvia void-free filling for printed circuit board application. Succinimide (SM), regarded as a leveler, is the core component of the bath. The action mechanisms of SM on microvia void-free copper filling are carefully expounded. UV–vis spectroscopy and theoretical calculations demonstrate that only the [Cu2(Cit)2]2– coordination ion exists in the bath containing SM at pH 9.0. Linear sweep voltammetry and in situ Fourier transform infrared spectroscopy combined with X-ray photoelectron spectroscopy experiments illustrate that SM can inhibit the electroreduction of the [Cu2(Cit)2]2– coordination ion and promote the electroreduction of intermediate Cu(I) to Cu(0), resulting in the improvement of coating quality. Galvanostatic measurements reveal that the reduction of the [Cu2(Cit)2]2– coordination ion is electrochemically controlled, and SM is diffusion-controlled. The leveler properties of SM (diffusion control and inhibition of [Cu2(Cit)2]2– coordination ion electroreduction) promote copper in bottom-up growing and void-free filling of microvias.