Etching methodologies in <111>-oriented silicon wafers

New methodologies in anisotropic wet-chemical etching of <111>-oriented silicon, allowing useful process designs combined with smart mask-to-crystal-orientation-alignment are presented in this paper. The described methods yield smooth surfaces as well as high-quality plan-parallel beams and membranes. With a combination of pre-etching and wall passivation, structures can be etched at different depths in a wafer. Designs, using the <111>-crystal orientation, supplemented with pictures of fabricated devices, demonstrate the potential of using <111>-oriented wafers in microsystem design.