Etching Methodologies in 111-Oriented Silicon Wafers

Abstract—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 sur-faces 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 fabri-cated devices, demonstrate the potential of using 111-oriented wafers in microsystem design. [523] Index Terms—Bulk micromachining, etch technology, 111 wafers, reactive ion etching, wet chemical etching. I