Electron radiation induced hydrocarbon contamination can be either a problem or a useful tool in electron beam analyses and lithographies. We have used atomic force microscopy to study electron beam written contamination structures. Contamination is shown not only to arise from the 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. By varying the geometry of the written structures, the rate at which the electron dose is deposited, and the nearby hydrocarbon surface density, we show that surface diffusion of hydrocarbon molecules plays a primary role in the formation of the contamination structures.