Specimen plane orientation determination for analysis based on scanning electron microscope: Comparing top-down and side-view approaches.

Abstract

Many attachments to a scanning electron microscope (SEM), such as energy dispersive x-ray spectroscopy, extend its function significantly. Typically, the application of such attachments requires that the specimen has a planar surface at a specific orientation. It is a challenge to make the plane of a microscale specimen satisfy the orientation requirement since they are visible only in an SEM. An in-situ procedure is needed to adjust specimen orientation by using stage rotation and tilting functions, in the process of which the key is to determine the initial orientation. This study proposed and tested top-down and side-view approaches to determine the orientation of a planar surface inside an SEM. In the top-down one, the projected area is monitored on SEM images as stage rotation and tilt angles are adjusted. When the surface normal is along the electron beam direction, the area has a maximum value. In the side-view approach, the stage is adjusted so that the projection appears to be a straight horizontal line on the SEM image. Once the orientation of the specimen for top-down or side-view observation is determined, the original can be calculated, and a desired orientation can be realized by manipulating the stage. The procedures have been tested by analyzing planar surfaces of spherical particles in Al-Cu-Fe alloy in the form of facets. The measured angles between two surfaces are consistent with those expected from crystallographic consideration within 2.7° and 1.7° for the top-down and side-view approaches, respectively. RESEARCH HIGHLIGHTS: Top-down and side-view approaches have been proposed and tested for in-situ determination of specimen planar surface orientation in a Scanning Electron Microscope. The measured angles between two surfaces are consistent with those expected from crystallographic consideration within 2.7° and 1.7° for the top-down and side-view approaches, respectively.