Scanning Electron Microscopy (SEM) of thin film magnetic disk defects is challenging due to lubricant on the disk surface. The lubricant aids disk durability but interacts with the electron beam to form a contaminantation layer over the area of interest. A new cleaning technology allows the removal of the surface contamination while the specimen is in the SEM.

Plasma dry ashing of SEM samples to remove surface hydrocarbons is a well-known technique for specimen preparation. A number of commercial external plasma cleaning units are on the market for sample preparation outside the microscope. Zaluzec developed a technique for plasma cleaning the specimen and stage together prior to insertion into the analytical region of the electron microscope. But similar plasma cleaning within the SEM chamber must be avoided due to ion bombardment damage to the SEM and the deleterious effect of argon plasmas on ion pumps. XEI Scientific has developed a new device that creates neutral oxygen radicals from air. This technique oxidizes surface hydrocarbons into volatile gases that are easily carried away to the roughing and diffusion pumps.