Laser-assisted etching of titanium foil in phosphoric acid for direct fabrication of microstructures

Characteristics of laser-induced thermochemical wet etching of titanium foil in phosphoric acid were investigated to examine the feasibility of this method for direct fabrication of microstructures. Variations of etch width, depth, and profile were examined for different combinations of laser power density, scanning speed of the beam focus, and etchant concentration which are the major process parameters governing temperature distribution on the sample surface and the reaction rate. Etch width increased almost linearly with laser power showing little dependence on scanning speed while etch depth showed wide variation with both laser power and scanning speed. A well-defined etch profile with good surface quality was obtained at high concentration condition but deteriorated as the concentration was lowered. Fabrication of microcantilever beam, microhole, and rectangular structure was demonstrated.