Surface and transverse morphology of micrometer nickel columns fabricated by localized electrochemical deposition

Micrometer nickel columns were fabricated locally on a copper substrate in a Watts bath by microanode guided electroplating which is commonly known as localized electrochemical deposition (LECD). A microanode of platinum (125 νm in diameter) served to move up intermittently, thus guiding the growth of Ni deposit from the substrate. The separation between the microanode and top of the microcolumn was initially set at 10 νm before setting out the electroplating. The electroplating current and local potential near the local region after the LECD were monitored and examined in this work. Surface and transverse morphology of the microcolumns were examined through a scanning electron microscope. LECD performed at biases less than 3.56 0.01 V led to columns with smooth surfaces and circular internal transverse fully compacted, whereas when performed at biases higher than 3.56 0.01 V it led to columns with a rough surface and distorted circular internal transverse with porosity in the center. The higher the bias, the worse the surface smoothness. The less circular the transverse, the less compactness in the transverse center. A compromise between the estimated supplying rate and the consumption rate of the nickel ions in the local region after the LECD is discussed to understand the dependence of the morphologies on the biases.