ATOMIC STEP IMAGING ON SILICON SURFACES BY SCANNING ELECTRON-MICROSCOPY

Factors influencing atomic step contrast of secondary electron (SE) images are investigated to obtain high quality step images using a scanning electron microscopy (SEM) instrument with a conventional objective lens. Contrary to high resolution SEM instruments in which specimens are positioned in the objective lens, the orientation of the step direction to the SE detector plays an important role in forming the atomic step contrast. Shadows are created by the atomic steps facing away from the SE detector due to low detection efficiency of SEs emitted away from the detector. Atomic step images are presented for Si(111) and Si(100) under the optimum conditions.