A study of coating techniques for ultra-thin film X-TEM sample preparation

Abstract

In this paper, we present a study on protective coating techniques for thin film X-TEM sample preparation. The study shows that proper choice of the protective layer before FIB cross section is a crucial step to maintain the film profile and make sure the accuracy of the thickness measurement. Silicon native oxide is used as the target sample. We have investigated PECS metal sputtering followed by ink coating, e-beam Pt and sputter Pt followed by ink coating. The granular feature of e-beam Pt coating is unwanted during native oxide thickness measurement. The PECS metal sputtering will create a damaged layer on top of the silicon substrate due to its high sputter energy. The damaged layer disguises the original substrate/oxide interface and leads the oxide thickness more difficult. The sputter Pt is the proper coating method based on this study. It provides a relative flat interface with high contrast at top of the oxide layer and does little damage to the substrate due to the low sputter energy.