Observation and control of Si surface and interface processes for nanostructure formation by scanning reflection electron microscopy

Abstract

We observe the oxidation process on clean Si surfaces using high-resolution scanning reflection electron microscopy and form nanostructures on them using focused electron-beam- (EB-) induced surface reactions. Si thermal oxidation occurs layer by layer, and the interface between the oxide film (<1 nm thickness) and Si substrate becomes atomically abrupt. When the sample is heated to 700-800 °C after being irradiated by the focused EB on the surface at room temperature, SiO2 film is selectively decomposed from the EB-irradiated area, resulting in the exposure of a clean Si substrate. The typical width of the clean Si `open windows' is about 10 nm. Using selective reactions during heating after the deposition of Si and Ge films on the patterned samples, Si nanowires and Ge nanoislands with 10 nm size are formed on Si surfaces. Ga-adsorbed Si nanoareas and Ga nanodots are also formed by selective adsorption of Ga on the Si window areas.