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The mechanisms responsible for the spatially inhomogeneous thickness of metal layers obtained by electrochemical deposition in magnetic gradient fields at small scale are being discussed controversially in the literature. The paper presents the results of numerical simulations which support the reasoning that local convection at the electrode driven by the rotational part of the magnetic gradient force is responsible for the effects observed. The deposition of paramagnetic and diamagnetic ions is discussed, and the influence of electrically inert magnetic ions present in the electrolyte is enlighted. [ABSTRACT FROM AUTHOR]

The relative influence of the Lorentz force and magnetic gradient force on micro-structured copper deposition is studied with simple magnetic elements consisting of cylindrical permanent magnets placed closely behind the surface of the cathode. Analytical findings and numerical simulations reveal that for magnets of small diameter the magnetic gradient force dominates. In experiments, it is found that the thickness of the deposited copper layer increases in the vicinity of the magnets. The combined analysis of simulations and experiments shows that this enhancement of mass transfer results from a local convection towards the electrode, which is forced by the magnetic gradient force. Finally, a more general case with electrically inert paramagnetic ions is discussed, where an inverse structuring effect can be expected. [ABSTRACT FROM AUTHOR]

In-situ velocity measurements were performed during potentiostatic Cu electrodeposition in different magnetic gradient fields (⊽B). Astigmatism Particle Tracking Velocimetry was used to enable three-dimensional measurements of al three velocity components in a large part of the cell volume. A complex three-dimensional fluid flow was observed. Thus, the magnetic field gradient force (F⊽B) driven electrode-normal convection during deposition in high ⊽B was experimentally proven and the interplay of F⊽B and the Lorentz force could be analysed for different ⊽B-setups. Moreover, in-situ measurements of the ion concentration during deposition and dissolution of Cu in a magnetic gradient field were performed by Mach-Zehnder interferometry. [ABSTRACT FROM AUTHOR]