Morphology and thermal stability of AlF3 thin films grown on Cu(100)

G. RUANO1, J. C. MORENO LOPEZ, M. C. G. PASSEGGI (JR.)1, R. A. VIDAL1, M. Á. NIÑO2, R. MIRANDA2,3, J. J. DE MIGUEL3,4, AND J. FERRÓN1,5

St. Petersburg

Congreso; 11th International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures; 2011

Aluminum fluoride (AlF3) is an inorganic resin with good insulator characteristics. It is chemically inert and thermally stable up to temperatures beyond 500K. AlF3 decomposes upon irradiation with low energy electrons, releasing F and leaving a deposit of metallic Al on the substrate, which makes it a good candidate for electron lithography.   In this work we studied the growth and thermal stability of AlF3 using a set of different characterization techniques that includes: i) Scanning Tunneling Microscopy (STM); ii) Auger Electron Spectroscopy (AES); iii) Thermal Energy Atom Spectroscopy (TEAS); iv) Electron Energy Loss Spectroscopy; v) Low Energy Electron Diffraction and vi) Ion Induced Secondary Electron Emission (SEE). AlF3 was thermally evaporated onto a Cu(100) substrate. We studied the growth mechanisms of the fluoride films from room temperature (RT) to 400K, and characterized their thermal stability up to 800K.  We found that AlF3 grows in a layer by layer fashion almost up to complete the first monolayer. The fluoride molecules initially decorate the Cu steps, having a diffusion length of around 10nm at RT. The islands show a dendritic shape characteristic of limited edge diffusion. Monolayer-thick deposits suffer a dewetting transition when annealed around 500K by direct or radiation heating.