Copper Layers Deposited on Aluminum by Galvanic Displacement

Ai, Jiahe; Liu, S. P.; Widharta, Newira A.; Adhikari, Saikat; Anderegg, James W.; Hebert, Kurt R.

doi:10.1021/jp2054266

Cited by 18 publications

(27 citation statements)

References 31 publications

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“…In some cases, copper layers with equivalent thickness of about 10−20 nm were found, suggestive of particulate deposits observed on planar substrates (see Supporting Information, Figure S1). 8 Here, we focus attention instead on thin film deposits found on some samples. For the conditions of the present experiments (50 mM CuSO 4 concentration, 2 min deposition time, tip radii of curvature between 65 to 180 nm), about 40% of the samples produced thin Cu films.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Atom Probe Tomography Characterization of Thin Copper Layers on Aluminum Deposited by Galvanic Displacement

Zhang

Hillier

et al. 2012

Langmuir

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Abstract″Ultrathin″ metallization layers on the order of nanometers in thickness are increasingly used in semiconductor interconnects and other nanostructures. Aqueous deposition methods are attractive methods to produce such layers due to their low cost, but formation of ultrathin layers has proven challenging, particularly on oxide-coated substrates. This work focused on the formation of thin copper layers on aluminum, by galvanic displacement from alkaline aqueous solutions. Analysis by atom probe tomography (APT) showed that continuous copper films of approximately 1 nm thickness were formed, apparently the first demonstration of deposition of ultrathin metal layers on oxidized substrates from aqueous solutions. The APT reconstructions indicate that deposited copper replaced a portion of the surface oxide film on aluminum. The results are consistent with mechanisms in which surface hydride species on aluminum mediate deposition, either by directly reducing cupric ions or by inducing electronic conduction in the oxide, thus enabling cupric ion reduction by Al metal. Disciplines Chemical Engineering CommentsReprinted with permission from Langmuir 28 (2012) ABSTRACT: ″Ultrathin″ metallization layers on the order of nanometers in thickness are increasingly used in semiconductor interconnects and other nanostructures. Aqueous deposition methods are attractive methods to produce such layers due to their low cost, but formation of ultrathin layers has proven challenging, particularly on oxide-coated substrates. This work focused on the formation of thin copper layers on aluminum, by galvanic displacement from alkaline aqueous solutions. Analysis by atom probe tomography (APT) showed that continuous copper films of approximately 1 nm thickness were formed, apparently the first demonstration of deposition of ultrathin metal layers on oxidized substrates from aqueous solutions. The APT reconstructions indicate that deposited copper replaced a portion of the surface oxide film on aluminum. The results are consistent with mechanisms in which surface hydride species on aluminum mediate deposition, either by directly reducing cupric ions or by inducing electronic conduction in the oxide, thus enabling cupric ion reduction by Al metal.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Atom Probe Tomography Characterization of Thin Copper Layers on Aluminum Deposited by Galvanic Displacement

Zhang

Hillier

et al. 2012

Langmuir

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“…6,20,26,44 Fig. 3 shows the time transition of OCPs measured for Al sheets immersed in the solutions without and with addition of TU.…”

Section: Resultsmentioning

confidence: 99%

Copper Galvanic Replacement on Aluminum from a Choline Chloride Based Ionic Liquid: Effect of Thiourea

Kang

Liang

Liu

et al. 2014

J. Electrochem. Soc.

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The deposition of copper (Cu) on aluminum (Al) is important for submicron interconnects and plating treatments of Al-based substrate. While aqueous deposition of Cu on Al is challenging on several technological and environmental problems. In this paper, we described electroless deposition of Cu onto Al surface through galvanic replacement from a simple and stable choline chloride (ChCl) based ionic liquid comprising a 1:2 stoichiometric mixture of ChCl and ethylene glycol (EG). Thermodynamic feasibility of Cu deposition by galvanic replacement on Al in ChCl-EG ionic liquid was studied by cyclic voltammetry. The effect of thiourea (TU) on the kinetics of galvanic replacement and the characterization of Cu layers were investigated by open circuit potential (OCP), electrochemical noise (ECN), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Results showed that sustained deposition of Cu on Al surface was achieved in both the ChCl-EG ionic liquid solutions without and with addition of TU. The presence of TU in the ionic liquid restrained the galvanic replacement process, resulting in obtaining a compact and uniform Cu layer on Al surface.Copper (Cu) is proposed as an interconnect metal for submicron integrated circuit technology due to its lower electrical resistivity compared to Al (∼1.7 vs. 3.0 μ · cm) and higher resistance to stressinduced voiding and electromigration. 1-4 The deposition of Cu metal onto Al has been developed as an important industrial process. In addition, the deposition of Cu is commonly used as a pretreatment method for coatings of Al substrates in order to obtain well-adhering coatings by substituting the naturally formed oxide film of Al. 5-7 The most common methods of producing Cu layer include electroplating 7,8,9 and electroless deposition. 10-12 Among them, electroless deposition is of special interest due to the advantages such as uniform deposition, convenient operation and a relatively low cost.Typical electroless deposition occurs through reduction process of metal ions in the presence of a reducing agent, which has been applied to many areas due to its low cost, low temperature process and simplified procedures. However, the process relies strongly on the composition of plating bath, which contains complex agent, reducing agent, some catalysts in addition to metal salts. 11 In the case of electroless Cu deposition, the conventional processes are usually related to technological and environmental problems. For example, the stability of the plating bath is not good enough. Some copper (II) ligands, reducing agents and acids, such as formaldehyde and hydrofluoric acid are not environmentally friendly. Moreover, the use of strong acids has an additional detrimental effect because of the etching of the substrates. [13][14][15] As a type of electroless deposition, galvanic replacement process has been explored for the growth of Cu layers on Al. 6,16 During the course of a galvanic replacement, the process occurs spontaneously and the reducing electrons are derived from the b...

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“…Although the galvanic displacement reaction of Cu on Al is possible from aqueous solutions, the presence of an oxide layer on Al inhibits the formation of uniform Cu coatings. Furthermore, strong alkaline solutions or F-containing solutions are required to remove the oxide layer from Al to facilitate the electroless deposition process (Ai et al, 2011; Ye et al, 2012). However, in ionic liquids, no F-containing additive was needed.…”

Section: Electroless Deposition Of Non-noble Metalsmentioning

confidence: 99%

A Review on the Electroless Deposition of Functional Materials in Ionic Liquids for Batteries and Catalysis

2019

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Developing functional materials via electroless deposition, without the need of external energy is a fascinating concept. Electroless deposition can be subcategorized into galvanic displacement reaction, disproportionation reaction, and deposition in presence of reducing agents. Galvanic displacement reaction is a spontaneous reduction process wherein the redox potentials of the metal/metal ion in the electrolyte govern the thermodynamic feasibility of the process. In aqueous solutions, the galvanic displacement reaction takes place according to the redox potentials of the standard electrochemical series. In comparison, in the case of ionic liquids, galvanic displacement reaction can be triggered by forming metal ion complexes with the anions of the ionic liquids. Therefore, the redox potentials in ILs can be different to those of metal complexes in aqueous solutions. In this review, we highlight the progress in the electroless deposition of metals and semiconductors nanostructures, from ionic liquids and their application toward lithium/sodium batteries, and in catalysis.

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Copper Layers Deposited on Aluminum by Galvanic Displacement

Cited by 18 publications

References 31 publications

Atom Probe Tomography Characterization of Thin Copper Layers on Aluminum Deposited by Galvanic Displacement

Atom Probe Tomography Characterization of Thin Copper Layers on Aluminum Deposited by Galvanic Displacement

Copper Galvanic Replacement on Aluminum from a Choline Chloride Based Ionic Liquid: Effect of Thiourea

A Review on the Electroless Deposition of Functional Materials in Ionic Liquids for Batteries and Catalysis

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