UHV-SEM Observation of Surface Electromigration with Silver Tip

Abstract

We have observed the surface electromigration with a silver tip by UHV-SEM and micro-probe RHEED. The silver tip etched and cleaned by heating and melting in UHV was mounted on a micro-slider touching heated Si(111) samples. The bright area under the silver tip is spread to the direction of cathode, the structure of which is determined to be √3×√3 structure from RHEED patterns. We have observed different shapes depending on heating temperature: At low temperatures, the shape of spread is like a bar, because the driving force of surface electromigration is superior to that of diffusion. At high temperatures, the shape is like a circle, because the driving force of diffusion is superior to that of surface electromigration. Using the silver tip, surface electromigration can be observed at high temperatures where lots of silver atoms are evaporated. We have checked the reproducibility of surface electromigration with the silver tip which is a supply source for thin film formation.