Ion and electron beam deposited masks for pattern transfer by reactive ion etching

We report on the use of a carbon-rich Pt-based material, obtained by electron and ion beam assisted deposition from metal-organic precursor, as a mask for pattern transfer processes. Thin and narrow mask patterns subjected to oxygen plasma and reactive ion etching (RIE) of silicon in SF(6) were investigated by atomic force microscopy and energy dispersive X-ray analysis. As for the masks obtained by electron beam assisted deposition, both the pattern and the surrounding halo were found to be etched in oxygen plasma. In contrast, the pattern deposited by assist of ion beam was basically unaffected, likely due to implanted Ga(+) ions during deposition, while the surrounding halo was found to be appreciably thinned. Masks having thickness as low as few nanometers sustained successfully a 200 nm RIE step, producing structures with sub-100 nm size. Mask stripping was achieved in Piranha bath.