Mechanical Polishing to Submicron Thickness for Extensive Thin Area in Heterogeneous Samples

Abstract

ABSTRACTIon-milling-based sample preparation has the advantage that thin area can be obtained from almost any material. It has the disadvantage, however, that the amount of thin area can often be quite limited. This poses a problem when a large sampling area is needed from materials which must be thinned by ion milling. Cross-sectioned samples and grossly heterogeneous materials are two examples where this problem may be encountered. The group at IBM in East Fishkill have developed methods for mechanical grinding and polishing of TEM samples down to about I micron thickness. They use this as a starting point for final thinning by ion milling. This approach produces a large uniform thin area in a short time in the ion mill. We have built jigs that allow us to make these mechanically-thinned samples. We have also made flat-bottomed dimples using ultra-precision dimple grinders to achieve similar results. Both of these approaches are described. Examples are taken from cross-section samples of thin films on silicon, from steels with large carbides, and from rapidly solidified metal spheres embedded in electroplated copper.