Guide to Coating for SEM Imaging

When exposed to the electron beam, non-conductive samples accumulate electrostatic charge, which can result in image distortions, defocussing, or bright spots on the SEM image. To prevent charge accumulation, techniques such as coating with a thin conductive layer, variable pressure SEM, low-kV imaging, beam deceleration, and environmental SEM (ESEM) can be employed. This application note highlights the importance of coating in SEM sample preparation and offers practical guidance on target material selection, recommended coating thickness, and the impact of vacuum pressure and current on coating quality across a wide range of applications.