Advantages of stereo imaging of metallic surfaces with low voltage backscattered electrons in a field emission scanning electron microscope

High emission current backscattered electron (HC-BSE) stereo imaging at low accelerating voltages (less than or equal to 5 keV) using a field emission scanning electron microscope was used to display surface structure detail. Samples of titanium with high degrees of surface roughness, for potential medical implant applications, were imaged using the HC-BSE technique at two stage tilts of +3 degrees and -3 degrees out of the initial position. A di gital stereo image was produced and qualitative height, depth and orientati on information on the surface structures was observed. HC-BSE and secondary electron (SE) images were collected over a range of accelerating voltages. The low voltage SE and HC-BSE stereo images exhibited enhanced surface det ail and contrast in comparison to high voltage (> 10 keV) BSE or SE stereo images. The low voltage HC-BSE stereo images displayed similar surface deta il to the low voltage SE images, although they showed more contrast and dir ectional sensitivity on surface structures. At or below 5 keV, only structu res a very short distance into the metallic surface were observed. At highe r accelerating voltages a greater appearance of depth could be seen but the re was less information on the fine surface detail and its angular orientat ion. The combined technique of HC-BSE imaging and stereo imaging should be useful for detailed studies on material surfaces and for biological samples with greater contrast and directional sensitivity than can be obtained wit h current SE or BSE detection modes.