A detailed study of scaling behavior in electrochemical etching of tungsten wires: Effects of non-uniform etching

We report electrochemical etching of a tungsten wire and its scaling behavior based on electrical resistance measurements. The resistance curve exhibits a unique power law, and yet its scaling exponent is found to be smaller than that expected on the basis of Ohm's law. A simple numerical analysis aided by atomic force microscopy indicates that the observed exponent is possibly subject to spatial non-homogeneity that occurs during an etching process in which individual wire segments tend to approach their own singular points. Despite this non-uniform etching, a unique value of scaling factor 0.84±0.060.84±0.06 has been obtained, consistent with a previous result.

► We have performed electrochemical etching of tungsten wires. ► A slightly reduced scaling exponent is observed from electrical resistance measurements. ► Surface inhomogeneity is shown to be responsible for the reduced scaling exponent. ► Despite inhomogeneity, the obtained exponent is consistent with a previous study.