Specimen preparation for the transmission electron microscopy is an unavoidable and critical step for any TEM experiments. It is frequently a very challenging task, which may decide about the success or fail of arduously planned TEM experiment. All of the existing methods for the TEM-specimen preparation follow one common principle – the thinner, the better, which means that the thickness of the TEM-specimen ideally should not exceed 100 nm (10nm for HRTEM). Furthermore, a high quality ultra-thin TEM-specimen should not only reflect the material properties on the nm scale, but also have a homogeneous and clean surface to avoid the measurement artefacts.
Conventional Sample Preparation
The conventional TEM-Specimen preparation begins with cutting the bulk sample into small pieces followed by several steps of half-automated material abrasion, until the specimen reaches the desired thickness. In a final step, argon ion milling helps to obtain the acquired ultra-thin electron transparent area.
FIB Sample Preparation
In contrast to time-consuming conventional TEM-specimen preparation methods, the focused ion beam (FIB) sputtering in a dual beam SEM system allows to produce high-quality specimens for various TEM studies in a (semi-)automated and much quicker way (within several hours). Modern dual beam FIB/SEMs use precise piezo-controlled manipulators, various gas injection systems to protect the sample surface, energy dispersive X-ray spectroscopy to measure composition and different detectors to image the specimen during the preparation process. In the dual systems, the imaging process results from using scanning electrons (SEM) whereby scanning of focused gallium ions at the sample surface enables local material abrasion.