In Ion Beam Etching (IBE), also known as Ion Beam Milling (IBM), an inert ion beam is used for pure physical sputtering of the sample material. This technique is commonly used for structuring metals or other materials which are not accessible to chemical etch processes. Reactive Ion Beam Etching (RIBE) uses reactive process gases to generate a reactive ion beam. Physical and chemical etch components and related selectivities may be easily varied by the energy of the ion beam. Finally Chemically Assisted Ion Beam Etching (CAIBE) uses an inert ion beam in a reactive gas background. Here the ions drive surface reactions with the absorbed reactive species. Based on these process features, ion beam etching might serve applications difficult to be addressed by common etch technologies.
Generally ion beam milling is applied for materials which may not be etched on a chemical basis, like most metals used in MEMS manufacturing. As a second important feature, one may utilize the directed ion flux and the angle dependence of the milling rate. This way defined and/or variable side wall angles in microstructures may easily be generated. Also, by choosing a specific ion incident angle, process rates and selectivity may be optimized.