Two-level electrochemical micromachining of titanium for device fabrication

The electrochemical micromachining of titanium structures relevant for biomedical applications was studied using a sulfuric acid methanol electropolishing electrolyte. Single-step etching of large sized cavities was performed and the effect on the dissolution depth of the presence of features of different sizes was evaluated. The fabrication of two-level structures by a two-step process was studied using consecutive dissolution steps through patterned photoresist masks. Two different strategies were compared for producing a model geometry consisting of a 10 mm diameter, 10 µm deep, flat-bottomed cavity containing a grid of 30 µm grooves. Results show that it is possible to fabricate the two-level model geometry by either first etching the cavity or the grooves. For the latter approach a numerical simulation of the shape evolution of the grooves during cavity etching permitted us to identify the most useful process window.