Anisotropic wet-chemical etching for preparation of freestanding films on Si substrates for atom probe tomography: A simple yet effective approach.

A major drawback of atom probe tomography (APT) experiments of complex samples is the demanding and rather time consuming specimen preparation via the lift-out process. It usually requires a skilled operator for focused ion beam (FIB) preparation, and frequently overbooked FIB workstations represent a major bottleneck in sample throughput. Within this work, the authors present an alternative approach for APT specimen preparation of functional films and coatings on Si substrates via anisotropic wet-chemical etching. Utilizing this simple, yet effective approach, a freestanding section of the film to be investigated can be fabricated in a few steps. After the etching procedure, freestanding film posts and subsequently APT specimen can be easily prepared by basic FIB milling operations without the need for a lift-out process. Hence, this approach reduces FIB efforts to a minimum in terms of complexity and required machine utilization.