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

Zhang, Yi; Ai, Jiahe; Hillier, Andrew C.; Hebert, Kurt R.

doi:10.1021/la204156d

Cited by 13 publications

(20 citation statements)

References 33 publications

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“…The presence of hydride at the Al/Al(OH) 3 interface is consistent with findings that the pH-dependence of the dissolution potential tracks closely with that of the Nernst potential of hydride oxidation [48,49]. APT images of the interfacial region indicated that hydride is dispersed at the nanoscale, as opposed to being segregated in isolated domains, thus implying that the same electrochemical potential applies at both Al and AlH 3 sites [47]. Expressing this potential in terms of both the Al and AlH 3 oxidation reactions yields the constraint, m Al À m 0…”

Section: Stress Generation Mechanismssupporting

confidence: 85%

“…The primary anodic reaction during corrosion is the oxidation of Al atoms to form Al þ3 ions incorporated into the Al(OH) 3 surface film; at the same time, aluminate ions dissolve from this film into the saturated alkaline solution [45]. Also, analytical evidence from Secondary Ion Mass Spectroscopy and Atom Probe Tomography (APT) indicate continuing formation of aluminum hydride (AlH 3 ) during alkaline dissolution [46,47]. The presence of hydride at the Al/Al(OH) 3 interface is consistent with findings that the pH-dependence of the dissolution potential tracks closely with that of the Nernst potential of hydride oxidation [48,49].…”

Section: Stress Generation Mechanismsmentioning

confidence: 99%

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Tensile stress and plastic deformation in aluminum induced by aqueous corrosion

et al. 2016

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a b s t r a c tMeasurement of near-surface stress generated by metallic corrosion can reveal defects and material property changes relevant to structural degradation by stress corrosion cracking. In this study, stress and topography evolution were characterized during alkaline corrosion of high-purity aluminum. In situ stress measurements revealed tensile increases of the force per width (stress integrated over depth) that scale directly with the sample yield stress. Spectral analysis of the uniform dimpled surface pattern produced by corrosion showed that transient changes of its characteristic wavelength track closely with the force per width. Together, the stress and topography measurements imply that corrosion creates a plastically deformed metal layer. Tensile stress is attributed to the lattice contraction associated with metal vacancies introduced during dissolution. In agreement with this hypothesis, a vacancy diffusion model successfully predicted the time dependence and magnitude of the force response, as well as the observed scaling relation between plastic layer thickness and pattern wavelength. The driving force for vacancy formation is thought to arise from high hydrogen and low aluminum chemical potentials near the corroding surface, the latter imposed by the high dissolution potential relative to the equilibrium potential of aluminum.

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Section: Stress Generation Mechanismssupporting

confidence: 85%

Section: Stress Generation Mechanismsmentioning

confidence: 99%

Tensile stress and plastic deformation in aluminum induced by aqueous corrosion

et al. 2016

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“…Such a transition for a MgO and Si cluster was also shown in previous papers. 7,8 We studied the field evaporation process of ZnO in APT. The evaporated ion species are Zn 2þ , ZnO 2þ , O 2 þ , and O þ , in good agreement with experiments.…”

Section: Discussionmentioning

confidence: 99%

“…APT was originally developed for the analysis of steels and alloys but in recent years it has also been adapted for the characterization of semiconductors and insulators with the assistance of ultrafast laser pulses. Metal oxides with thicknesses of the order of 10 nm, such as NiO, 3,4 Fe 1Àx O, 5 Al 2 O 3 , 6,7 MgO, [8][9][10][11] and ZnO 9-12 deposited on metal tips, have been analyzed successfully. A variety of positively charged atoms and molecules are observed in the mass spectra.…”

Section: Introductionmentioning

confidence: 99%

Field evaporation of ZnO: A first-principles study

Karahka

Kreuzer

2015

Journal of Applied Physics

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With recent advances in atom probe tomography of insulators and semiconductors, there is a need to understand high electrostatic field effects in these materials as well as the details of field evaporation. We use density functional theory to study field effects in ZnO clusters calculating the potential energy curves, the local field distribution, the polarizability, and the dielectric constant as a function of field strength. We confirm that, as in MgO, the HOMO-LUMO gap of a ZnO cluster closes at the evaporation field strength signaling field-induced metallization of the insulator. Following the structural changes in the cluster at the evaporation field strength, we can identify the field evaporated species, in particular, we show that the most abundant ion, Zn2+, is NOT post-ionized but leaves the surface as 2+ largely confirming the experimental observations. Our results also help to explain problems related to stoichiometry in the mass spectra measured in atom probe tomography.

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“…Whereas the portion of the surface film on Al contacting the alkaline solution is composed of aluminum oxide or hydroxide, 21 evidence from our laboratory supports previous findings by Perrault that the interior of the film contains appreciable (AlH 3 ). 22 We detected interfacial aluminum hydride within the surface film by secondary ion mass spectrometry and atom probe tomography (APT) 23,24 and showed that the electrochemical potential at the metalÀfilm interface is close to the Nernst potential of the hydride oxidation reaction. 25,26 Because borohydride ions in solution can mediate ELD of copper from alkaline baths, a similar role for surface AlH 3 seems possible 27,28 We show here that simple galvanic displacement from alkaline baths can deposit thin Cu metal layers on Al in certain ranges of pH, copper concentration, and process time.…”

Section: à16mentioning

confidence: 99%

Copper Layers Deposited on Aluminum by Galvanic Displacement

Liu

Widharta

et al. 2011

J. Phys. Chem. C

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Metallization layers nanometers to tens of nanometers thick are desirable for semiconductor interconnects, among other technologically relevant nanostructures. Whereas aqueous deposition of such films is economically attractive, fabrication of continuous layers is particularly challenging on oxidized substrates used in many applications. Here it is demonstrated that galvanic displacement can deposit thin adherent copper layers on aluminum foils and thin films from alkaline copper sulfate baths. According to scanning electron microscopy and quartz crystal microbalance measurements, the use of relatively low CuSO4 concentrations produced films composed of copper nanoparticles overlying a uniform continuous copper layer on the order of nanometers in thickness. It seems that there are no precedents for such thin layers formed by aqueous deposition on oxidized metals. The thin copper layers are explained by a mechanism in which copper ions are reduced by surface aluminum hydride on Al during alkaline dissolution. Keywords Ames Laboratory Disciplines Chemical Engineering CommentsReprinted with permission from Journal of Physical Chemistry C 115 (2011) Because of their cost effectiveness, solution-based thin-film deposition techniques are widely integrated in semiconductor interconnect and MEMS technology. "Ultrathin" metallization layers of a few nanometers thickness are particularly beneficial in applications involving nanostructured substrates. In semiconductor interconnects, the ability to produce such deposits would eliminate the need for vapor-deposited seed layers for copper electrodeposition on TaN or TiN barrier materials. Efforts to produce seed layers by direct electrodeposition onto the barrier are hindered by the insulating, spontaneously formed oxide films on these materials. 1À4 Electroless deposition (ELD) methods, in which the deposited metal ion is chemically rather than electrochemically reduced, are attractive because they do not require conductive substrates. ELD of Cu on barrier materials has been demonstrated. 5À7 Galvanic displacement, in which either the substrate itself or adsorbed atoms reduce the deposited metal ions, has been explored extensively for fabrication of metal films on semiconductors and noble metals, 8,9 and copper layers on barrier materials have been reported. 10,11 However, it seems that ultrathin films on oxidized substrates have not yet been fabricated by either ELD or galvanic displacement.The present Article concerns the deposition of thin copper layers on aluminum by galvanic displacement. Aluminum exemplifies substrates having a surface oxide that interferes with solution-phase thin film deposition. Micron-thick particulate Cu films displaying good adhesion can be electrodeposited from alkaline sulfate baths; 12 also, several techniques have been developed to disrupt Al oxide layers to promote electrodeposition. 13À16Evidence of these papers suggests that deposition is promoted by alkaline solutions or by cathodic applied potentials at which hydrogen evolution...

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

Cited by 13 publications

References 33 publications

Tensile stress and plastic deformation in aluminum induced by aqueous corrosion

Tensile stress and plastic deformation in aluminum induced by aqueous corrosion

Field evaporation of ZnO: A first-principles study

Copper Layers Deposited on Aluminum by Galvanic Displacement

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