Plan-view preparation of TEM specimens from thin films using adhesive tape

A simple plan-view sample preparation technique for transmission electron microscopy (TEM) specimens is proposed for thin films by tearing-off the film with adhesive tape. The demand for very thin samples is highest for nanostructured materials where the structure of 2-5 nm sized features (grains) needs to be resolved; therefore, overlapping of nanometer-sized features should be avoided. The method provides thin areas at the fracture edges of plan-view specimens with thickness in the range of the grain size in the film allowing for artifact free high-resolution TEM imaging. Nanostructured materials typically fracture between the grains providing areas with the thickness of the grain size. Besides the swiftness of the method, the samples are free of surface amorphization artifacts, which can occur in ion beam milling up to 1 nm depth even at low energy ion bombardment. The thin film tear-off technique is demonstrated on a CuMn alloy thin film with grain size of 2 nm.