Advanced Techniques in TEM Specimen Preparation

The recent development of Dual-BeamTM or Cross-BeamTM FIB systems has gradually taken over the traditional single beam FIB systems. A typical FIB column contains a liquid metal ion source that produces a finely focused Ga ion beam. The primary Ga ion beam is accelerated by 30-50 kV, and directed towards the features of interest on the specimen. The incident ion beam will sputter atoms from the specimen surface, producing both secondary ions and secondary electrons. Depending on the application, the beam current can be set to high (e.g. over 60 nA) for rapid ion beam milling. Aside from electron beam imaging, operator can perform high-resolution ion beam imaging (up to 2.5 nm imaging resolution in some FIB systems). Site-specific micro-depositions (e.g., Pt, W, C, and SiO2) and microetching can also be achieved by the interaction of the primary ion beam (or electron beam) with the deposition (or etching) gas introduced into the system. Figure 1 shows a schematic diagram of ion-specimen interaction in FIB microscopes.