Investigation of Galvanic Corrosion Between TaN[sub x] Barriers and Copper Seed by Electrochemical Impedance Spectroscopy

Abstract

In this article, electrochemical impedance spectroscopy is used to characterize the mechanism of galvanic corrosion between copper ͑Cu͒ seeds and tantalum nitride ͑TaN x ͒ barriers deposited with different N 2 flow rates. By way of software simulating with EIS data, an equivalent circuit is built up to explain the corrosion behavior of the TaN x films' relation to the Cu seeds in an acidic chemical-mechanical-polishing slurry. The equivalent circuit can respond to changes in resistance and capacitance elements of the Cu-TaN x electrochemical system. It is found that the charge-transfer resistance of the TaN x galvanic corrosion increases with the N 2 flow rate, whereas the resistance of a tantalum-oxide layer is opposite because increasing the N content of the TaN x films inhibits corrosion and oxidation of the Ta metals. The result is consistent with our previous investigation that the galvanic corrosion of the TaN x films to the Cu seeds is retarded by the N element ͓C.

Visualizing Nanoscale Distribution of Corrosion Cells by Open-Loop Electric Potential Microscopy

“…At the wire edges, a 25 nm Ta layer is inserted between the Cu and SiO 2 regions. The Cu/Ta contact leads to the formation of galvanic corrosion cells. , In addition, the crystallinity of the Cu wires near the interface is lower than that at the center. These factors accelerate corrosion at the interface to form a line-shaped crevice along the wire edges as shown in Figure i.…”

Investigation of the Galvanic Effect between RuN Barriers and Cu Seed Layers

“…10) Moreover, the degree of galvanic corrosion between Cu and various barrier materials including their nitrides has been widely investigated. For example, Hung et al reported that the galvanic corrosion of the TaN x films to Cu seed layers is retarded by N. 32,33) However, to date there have been few studies about the galvanic effect between the RuN x films and Cu seed layers. To address this gap in the literature, in the present study, we investigate the galvanic effect between Cu seed layers and RuN x films deposited at various N 2 gas flow rates in CMP slurries by electrochemical impedance spectroscopy (EIS), [34][35][36][37][38][39] energy dispersive X-ray (EDX), and fieldemission scanning electron microscopy (FESEM).…”

Effect of Under-Layer Treatment of Ta/TaN Barrier Film on Corrosion Between Cu Seed and Ta in Chemical-Mechanical-Polishing Slurry

“…In our previous study, the mechanism of galvanic corrosion between the Cu seeds and the TaN x barriers deposited with various N 2 flow rates were investigated using field-emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX), and electrochemical impedance spectroscopy (EIS). [13][14] We demonstrated that TaN x films and the Cu seed had * Author to whom correspondence should be addressed. both intrinsic corrosion and galvanic corrosion in an acidic CMP slurry.…”