Improved sample preparation for cross-sectional transmission electron microscopy of layered structures using rocking-angle ion-milling techniques.

The rocking-angle ion-milling technique has been employed to produce optimum Pt/Ti/SiO2/Si, W/TiN/SiO2/Si, and (Pb,La)TiO3/Pt/MgO samples for cross-sectional transmission electron microscopy (TEM). Because of the different ion-milling rates between film layers and substrate materials, no satisfactory cross-sectional TEM samples could be obtained when they were made by the conventional ion-milling method. The differential thinning problems could be effectively solved by optimizing both ion-milling rocking-angle and ion-beam incidence angle without the increase of overall milling time. It was found that the rocking-angle of around 40 degrees is good when the multilayer structure is composed of materials with great ion-milling rate differences, while the rocking angle of around 80 degrees is good when the ion-milling rate differences are relatively small.