During the past two decades, the scanning electron microscope (SEM) has become an indispensable tool for morphological observation in materials and biological sciences. With energy dispersive x-ray spectroscopy (EDS) and wavelength dispersive spectroscopy (WDS), rapid chemical characterization of microscopic features has also become commonplace. As developments in manufacturing methods allow fabrication of ever smaller devices and quality control has achieved higher priority, demand for microscopic characterization by SEM has continuously increased.
Many applications where SEM/EDS evaluation could be useful involve samples that are not electrically conductive. Nonconductive samples are subject to a buildup of electrons on the examined surface. This buildup of electrons, or “charging” eventually causes scattering of the incoming electron beam, which interferes with imaging and analysis. Nonconductive samples have traditionally required pretreatment, by coating with a conductive film, before SEM examination.