Specific Area Planar and Cross-Sectional Lift-Out Techniques: Procedures and Novel Applications

Abstract

Abstract Conventional focussed ion beam (FIB) based specific area transmission electron microscopy (TEM) sample preparation techniques usually requires complex grinding and gluing steps before final FIB thinning of the sample to electron transparency (<0.25 μm). A novel technique known as lift-out, plucking or pullout method that eliminates all the pre-FIB sample preparation has been developed for specific area TEM sample preparation by several authors. The advantages of the lift-out procedure include reduced sample preparation time and possibility of specific area TEM sample preparation of most components of integrated circuit with almost no geometric or dimensional limitations. In this paper, details of liftout method, developed during the present work, for site specific x-sectional and a new site specific planar sample preparation are described. Various methodologies are discussed to maximize the success rate by optimizing the factors that affect the technique. In failure analysis, the geometric and dimensional flexibility offered by the lift-out technique can be used to prepare specific area TEM sample of back thinned die, small particles and packaged parts. Such novel applications of lift-out technique in failure analysis are discussed with the examples of TEM results obtained from GaAs and Si based devices. Importantly, it was possible to obtain high resolution lattice images from the lift-out samples transferred on holey carbon supported 3mm copper grids.