TEM sample preparation for a suspended structure with deep cavity

Transmission electron microscope (TEM) failure analysis has been widely adopted in the field of semiconductor manufacturing because of its ability to provide high resolution measurement and elemental characterization in (sub) nanometer scale. Despite many advantages of the TEM technique, one challenge that the conventional sample preparation by Focused Ion Beam (FIB) is limitations on the TEM lamella size, structure, or pattern of the target. In this work, we demonstrate how TEM lamellas were prepared on a suspended structure with deep cavity. In the first case study, proper selection of coating materials with tilted angle deposition and use of in-situ lift-out technique are critical for successful sample preparation to study thin residue layer along large sidewall of a suspended structure. In the second case study, application of fine cleaving and sample reorientation enabled us to prepare an artifact-free sample to characterize post-etch residue at the bottom of a very deep cavity.