The dissolution of copper in solutions containing Glutamic acid and hydrogen peroxide is analyzed using EIS. Potentiodynamic polarization studies show that there is no strong passivating layer formed on the copper surface in solutions containing 0.5 wt% Glu and 0.1 vol% hydrogen peroxide. Electrochemical impedance spectra of copper in this solution at various overpotential were acquired and modeled using electrical equivalent circuit and reaction mechanism analysis. The results show that the reaction involves at least two adsorbed intermediates. ©The Electrochemical Society.

Srinivasan Ramanathan

Department Of Chemical Engineering

ADSORBED INTERMEDIATES

COPPER DISSOLUTION

Copper surface

Electrical equivalent circuit

ELECTROCHEMICAL IMPEDANCE SPECTRA

glutamic acid

OVERPOTENTIAL

Passivating layer

POTENTIODYNAMIC POLARIZATION STUDIES

REACTION MECHANISM ANALYSIS

Amino acids

Copper

Hydrogen peroxide

Reaction intermediates

Electrochemical corrosion

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Analysis of Copper Dissolution in Glutamic Acid and Hydrogen Peroxide Using EIS

ECS Transactions

Analysis of copper dissolution in glutamic acid and hydrogen peroxide using EIS

The effect of l-glutamic acid as complexing agent in the presence of hydrogen peroxide as oxidizer in copper chemical mechanical polishing (CMP) slurry is investigated. In the CMP process, the work surface is moved against a pad, with slurry flowing between the surface and the pad. The polish rate was found to be stable over a wide range of hydrogen peroxide concentration. High concentration of either l-glutamic acid or hydrogen peroxide leads to a reduction in polish rate, but a high concentration of both chemicals does not reduce the polish rate. In the absence of hydrogen peroxide, the Cu polish rate was 0 for all the l-glutamic acid concentrations investigated. However, potentiodynamic polarization curves do not show any sign of passivation when l-glutamic acid was present in the solution. In situ open circuit potential measurements show that copper redox reactions as well as hydrogen peroxide redox reactions contribute in determining the electrochemical behavior. We propose that l-glutamic acid inhibits the copper dissolution by adsorption onto the metallic copper, but enhances copper dissolution by complexing copper ions. The results show that it is possible to conduct controllable copper CMP in mildly acidic slurries with hydrogen peroxide as oxidizer and l-glutamic acid as complexing agent. © 2010 Springer-Verlag.

Journal of Solid State Electrochemistry

Electrochemical characterization of copper chemical mechanical polishing in l-glutamic acid-hydrogen peroxide-based slurries

Chemical mechanical polishing (CMP) of copper in ammonium hydroxide based slurry in the presence of hydrogen peroxide was investigated. The polishing trend was found to be similar to that exhibited by other slurries containing hydrogen peroxide and various complexing agents used for Cu CMP. When the hydrogen peroxide concentration is increased, the polish rate increases, reaches a maximum and then decreases. The location and the magnitude of the maximum depend on the ammonium hydroxide concentration. The dissolution of copper in the NH4OH-hydrogen peroxide solution was probed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) experiments. Electrical equivalent circuit (EEC) and reaction mechanism analysis (RMA) were employed to determine the mechanistic reaction pathway of Cu dissolution in NH4OH-hydrogen peroxide system. Based on the RMA analysis, a four step catalytic mechanism with two adsorbed intermediate species is proposed. © 2009 Springer Science+Business Media B.V.

Journal of Applied Electrochemistry

Electrochemical characterization of Cu dissolution and chemical mechanical polishing in ammonium hydroxide-hydrogen peroxide based slurries

Electrochemical Impedance Spectroscopy (EIS) is a sensitive technique for determining the mechanistic pathway of an electrochemical reaction. In particular, the low frequency behavior of the impedance at various over-potentials can help differentiate between very similar mechanisms. Nine different mechanisms related to anodic dissolution of metals are simulated and the EIS patterns that are expected for these mechanisms are identified. This library of patterns reported here will help in eliminating certain mechanisms and identifying mechanisms with the least number of parameters that can be applied for modeling experimental EIS data. © 2009 Elsevier B.V. All rights reserved.

Fulltext

Journal of Electroanalytical Chemistry

Identification of reaction mechanism for anodic dissolution of metals using Electrochemical Impedance Spectroscopy

Anodic dissolution of copper in arginine and hydrogen peroxide-based medium suitable for chemical mechanical planarization slurry formulation was investigated using electrochemical impedance spectroscopy. Potentiodynamic polarization and impedance data were acquired for copper dissolving in hydrogen peroxide and arginine solution. Reaction mechanism analysis (RMA) was employed to determine the mechanistic pathway of copper dissolution. RMA analysis indicates that a stable passivating film does not form on the copper surface, and the direct dissolution of copper was also ruled out. A two-step mechanism involving cupric oxide as an intermediate species is proposed. The data were also fit to an electrical equivalent circuit to obtain insight into the variation of the parameters with the overpotential. The modeled data for the two-step mechanism captures the essential features of the impedance spectra at various overpotentials. © 2008 Springer-Verlag.

Electrochemical impedance spectroscopic studies of copper dissolution in arginine-hydrogen peroxide solutions

Journal	ECS Transactions
ISSN	19385862
Open Access	No