ATOMIC-FORCE MICROSCOPY STUDY OF ELECTRON-BEAM WRITTEN CONTAMINATION STRUCTURES

Electron radiation induced hydrocarbon contamination can be either a p roblem or a useful tool in electron beam analyses and lithographies. W e have used atomic force microscopy to study electron beam written con tamination structures. Contamination is shown not only to arise from t he primary electron beam but also from the energy scattered outside of the direct impingement area. The size of the contamination structures correlates well with that expected from electron scattering theory. B y varying the geometry of the written structures, the rate at which th e electron dose is deposited, and the nearby hydrocarbon surface densi ty, we show that surface diffusion of hydrocarbon molecules plays a pr imary role in the formation of the contamination structures. (C) 1996 American Vacuum Society.