Advances in atom probe specimen fabrication from planar multilayer thin film structures

A sample preparation method has been developed whereby sharp needle-shaped specimens for atom probe analysis are fabricated from multilayer thin films deposited onto silicon substrates. The specimens are fabricated in an orie ntation such that atom probe composition profiles across the layer interfac es can be determined with atomic-layer spatial resolution, i.e., the layer normals are parallel to the needle axis. The method uses standard silicon e tching techniques and focused ion-beam milling. The feasibility and utility of this technique are shown through its application to a NiFe/CoFe/Cu/CoFe -based thin film structure.