Chemically assisted ion-beam etching in a low-angle ion mill

Abstract

In conventional ion mills, chemically assisted ion beam etching (CAIBE) has become an establish method for TEM specimen preparation of certain materials. CAIBE employs a reactive gas which brought in contact with the specimen through a jet assembly, while an inert gas ion beam is directed on the same area. Therefore, thinning occurs by the combination of chemical reaction and physic sputtering, which leads to enhanced thinning rates. The reactive gas used in the CAIBE technique can generated from a solid source which sublimes e.g. iodine or it can be injected directly from a pressuriz gas bottle e.g. nitrous oxide. Nitrous oxide in combination with a xenon ion beam has been used from cross sectioning TEM specimens of diamond films on silicon.It is well known that indium-containing compound semiconductors develop indium islands on the surface when thinned with an argon ion beam. It is believed that preferential sputtering enriches the surface with indium and that heating by the ion beam melts the indium which then agglomerates to for small globules on the surface.