Single-mask, high aspect ratio, 3D micromachining of bulk titanium

This paper reports the development of a simple method for 3D microfabrication of complex, high aspect ratio structures with arbitrary surface height profiles in bulk titanium. The method relies on the exploitation of reactive ion etching lag (RIE Lag) to simultaneously define all features using a single lithographic masking step. Modulation of the mask pattern openings used to define the features results in etch depth variation across the pattern, which is then translated into surface height variation through removal of the superstructures above the etched floor. The utility of this approach is demonstrated in the fabrication of a sloping electrode structure intended for application in bulk micromachined titanium micromirror devices.