Effect of applied magnetic field on microstructure of electrodeposited copper

There have been many fundamental studies on magnetic field-assisted electrodeposition that focus on the initial stages of thin film deposition but not on the resulting microstructural features (texture, grain size, grain boundary character, phase distribution) of the plating. In this communication we present results on the influence of a gradient magnetic field on the microstructural features of thick (>100μm) electrodeposited copper films. It is shown by electron backscatter diffraction characterization that the application of a gradient magnetic field influenced the grain size and twin boundary fraction. Depletion of Cu2+ ions at the substrate caused by the magnetic gradient force resulted in lower plating thicknesses and larger grain sizes when the direction of applied magnetic field and current was parallel. On the other hand, the magnetic field has little effect on the thickness and grain size for the anti-parallel case. In all cases increased convective flow offered by local magnetohydrodynamic effect resulted in substantially higher twin boundary fraction.