IAEA-CN-115-23 · Proton beam writing in silicon

E. J. Teo ^1,2, M. B. H. Breese ¹, D. Mangaiyarkarasi ¹, A. A. Bettiol ¹, F. Champeaux ¹, F. Watt ¹ and D. J. Blackwood ²

¹Centre for Ion Beam Applications, Physics Department, National University of Singapore, Lower Kent Ridge Road, Singapore 119260
²Materials Science & Engineering Department, National University of Singapore, Lower Kent Ridge Road, Singapore 119260

Abstract: Proton beam writing has been used to pattern p-type silicon prior to electrochemical etching in hydrofluoric acid. The ion beam selectively damages the silicon lattice, resulting in an increase in the local resistivity of the irradiated regions. This damage acts to slow down the rate of porous silicon formation and modify the properties of porous silicon. The photoluminescence intensity of the irradiated regions is found to increase with proton irradiation into a 0.02 Ω.cm resistivity p-type silicon. In fact, the intensity increases as the fluence increases from 5×10¹⁴ to5×10¹⁵ protons/cm². By immersing the etched sample into potassium hydroxide, the porous silicon is removed to reveal the underlying three-dimensional structure of the patterned area. As the layer of porous silicon layer becomes thinner with increasing fluence, the remaining structure will have a taller feature height. This technique allows the production of a structure with multiple heights by varying the fluence of the beam.

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