SPECIFIC SITE CROSS-SECTIONAL SAMPLE PREPARATION USING FOCUSED ION-BEAM FOR TRANSMISSION ELECTRON-MICROSCOPY

Sample preparation using focused ion beam (FIB) for transmission Elect ron Microscopy (TEM) analysis was reviewed. Improving the quality of F IB prepared TEM sample has been an issue in the past. A specific site cross-sectional sample preparation method has been developed using FIB milling for TEM characterization of integrated circuits (ICs). Approa ch of front side and back side milling has been applied to thin the se miconductor samples for electron transparency. Back side milling has b een applied for the first time in our TEM sample preparation using FIB milling. Proper tilting of the stage and use of low beam current are found to be critical for TEM samples quality. Samples prepared during present work are thinner, artifact-free, and of excellent quality for TEM analysis. It is possible to prepare specific site cross-sectional TEM samples of ICs within 2-3 hours using FIB milling. Some examples o f specific site cross-sectional TEM analysis of Si based device struct ures are presented. Final achievable thicknesses of the samples are ex emplified from the fact that atomic resolution imaging was possible an d microstructure was seen in the tungsten plugs.