Copper Underpotential Deposition on Gold in the Presence of Polyethylene Glycol and Chloride

Chiu, Yong Da; Dow, Wei Ping; Liu, Yung Fang; Lee, Yuh Lang; Yau, Shueh Lin; Huang, Su

doi:10.1016/s1452-3981(23)18261-7

Cited by 11 publications

(1 citation statement)

References 51 publications

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“…The accelerator promotes Cu reduction on the bottoms of vias or trenches, while the suppressor and the leveler restrain Cu deposition on the sides of vias or trenches and the superfluous Cu bumps. Among them, the suppressor plays an indispensable role in achieving “bottom-up” filling in Cu interconnects in the presence of chloride ions. − In most cases, suppressors are large alkyl-ether polymers or copolymers, such as polyethylene glycol (PEG), polypropylene glycol (PPG), or triblock copolymer composed of ethylene oxide (EO)–propylene oxide (PO)–ethylene oxide (EO) …”

Section: Introductionmentioning

confidence: 99%

Revisiting the Polyethylene Glycol-Chloride Adsorption Structure on Cu Electrode in Sulfuric Acid Solution by Wide-Frequency ATR-SEIRAS

Wu,

Mao,

Jiang

et al. 2023

J. Phys. Chem. C

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Polyethylene glycol (PEG) is a typical suppressor in the presence of chloride anions for Cu interconnect electroplating in the field of microelectronics manufacture, yet its adsorption structure and its correlation with the inhibition effect remain controversial and unclear. In this work, wide-frequency attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is utilized to clarify the interfacial adsorption structure of PEG with Cl– on a Cu electrode, providing direct molecular-level evidence for the inhibition effect. Time-resolved spectroscopic results show that the OC–CO subunit of PEG transforms from trans to gauche conformation with the addition of Cl– in a way favoring the hydrocarbon sections of PEG to lean toward the Cl–-covered Cu surface, as demonstrated by the evolution of characteristic peaks at 1134, 1090, and 848 cm–1 as well as that of interfacial water stretching vibration bands (ca. 3400–3650 cm–1). Moreover, a comparison of spectra for adsorbed PEG and dissolved PEG shows that more OC–CO and CC-OC gauche conformations are present in the former, in favor of PEG chain coiling to form mounds on the Cl–-covered Cu electrode. The steric hindrance of as-formed PEG mounds may account for the strong interfacial inhibition effect of the PEG-Cl– adstructure, as supported by the electrochemical quartz crystal microbalance (EQCM) measurement. A series of potential-dependent ATR-SEIRAS spectra reveal that with decreasing potential, the coiled PEG chains become loosened due to gradual desorption of the underlying Cl– adlayer.

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