Techniques to create three-dimensional microstructures are still a matter o
f research, and localized electrodeposition is a promising path to inexpens
ive free-form microfabrication in metal. The principle is to put the tip of
a needle very close to a conducting substrate submerged in a plating bath,
apply typically 4-5 V, and move the tip as the metal deposits. In this pap
er we report improved deposition control and the benefits of adding ammonia
and ammonium formate to nickel plating solutions for enhanced resolution a
nd surface smoothness. A mirror-smooth 600 mu m tall nickel column 3 mu m i
n diameter was built at 3 mu m/s. Still higher axial deposition rates could
be attained, as well as structure diameters down to 2 mu m. The broadening
of previously built structures near the one being grown was studied, and t
he usefulness of an auxilliary electrode was confirmed. The possibility of
branching and joining structures was also investigated in order to realize
the vision of building structures of arbitrary shapes. (C) 2000 The Electro
chemical Society. S0013-4651(99)05-011-9. All rights reserved.