Helium FIB offers the capacity for nanometer scale maskless ion beam lithography.
We present work performed on the new Zeiss Helium, Neon, Gallium FIB installed at MNRF at RMIT University. This instrument has 0.3 nm imagining resolution and milling of structures down to 10 nm with helium. The triple ion capacity of this tool enables direct comparison of the damage and milling capacity of each ion in the one instrument.
The helium beam is used for ultra-fine milling <100 nm, the neon beam machines nanostructures at great speed and achieves high throughput while the gallium FIB removes larger volumes of material. The instrument has a field of view up to 1.4 mm, sample biasing and flood gun operation for charge neutralization on insulating samples.
We present nanostructured gold devices, machined for nanogap electrodes and SERS structures (surface-enhanced Raman spectroscopy) fabricated at MNRF, RMIT. A 110 nm thick film of Cr/Au deposited on SiO2/Si wafer was FIB milled producing separations as small as 40 nm, Fig. 1.
Fig 1: SEM image of the helium FIB trench, 40 nm wide in a 110 nm layer of Cr/Au.
Gallium milling for optical devices can result in ion poisoning and excess fluorescence which detract from device performance [1, 2]. Helium and neon milling offer a non chemically reactive milling ion that may reduce these milling side effects for optical and electrical device fabrication.