High Speed TEM Sample Preparation by Xe FIB

Preparation of Transmission Electron Microscope (TEM) samples by Focused Ion Beam (FIB) milling is one of the most precise techniques now routinely used for example in failure analysis or material science. These TEM samples are commonly prepared using Ga FIB technology, starting more than 20 years ago [13]. Presently FIB columns are commonly combined with the Scanning Electron Microscopy (SEM) technique for observation during the preparation process and for the enhanced navigation, end-pointing and analytical capabilities. This FIB-SEM combination makes TEM sample preparation process much easier than before. However, when TEM sample size increases to several tens of m, the preparation time increases considerably due to low Ga FIB milling speed. This preparation time drops the throughput of the method and limits the size of Ga-FIB-prepared samples to 5-10 m. The new Xenon plasma FIB tool equipped by ECR plasma ion source (i-FIB) offers more than 50x higher milling speed, while still having sharp current distribution well adapted for sub-100 nm thickness samples preparation required for high-quality TEM images. TEM sample preparation obtained with a single-beam plasma FIB instrument has already been shown [4]. Nevertheless, the combination of the high resolution SEM and the high current plasma FIB [5, 6] offers more chance to speed up the preparation of extremely large TEM samples. This lecture will present the first results of the large TEM lamella preparation by ECR plasma FIB (Orsay Physics) which currently equips the SEM-FIB TESCAN FERA3 instrument. The different steps of extra-large TEM lamella preparation will be detailed (deposition of protective layer, rough milling, polishing and TEM imaging of the prepared sample).