Gas-assisted silver deposition with a focused electron beam

Abstract

Focused electron beam induced deposition (FEBID) is a flexible direct-write method to obtain defined structures with a high lateral resolution. In order to use this technique in application fields such as plasmonics, suitable precursors which allow the deposition of desired materials have to be identified. Well known for its plasmonic properties, silver represents an interesting candidate for FEBID. For this purpose the carboxylate complex silver(I) pentafluoropropionate (AgO2CC2F5) was used for the first time in FEBID and resulted in deposits with high silver content of up to 76 atom %. As verified by TEM investigations, the deposited material is composed of pure silver crystallites in a carbon matrix. It showed good electrical properties and a strong Raman signal enhancement. Interestingly, silver crystal growth presents a strong dependency on electron dose and precursor refreshment.

Towards the third dimension in direct electron beam writing of silver

“…Besides that the molecular structure is very similar, which leads to the expectation that also AgO 2 F 5 Prop will show a strong sensitivity to electron beam impact. Indeed, this could be proven by earlier investigations [ 27 ].…”

“…They exhibit different diameters from around 1 µm for 50 pA to 1.5 µm for 150 pA and almost 2.5 µm for 500 pA. The pillar widths correspond to the full width FW (99.9%) of the SE density [ 9 , 27 ] but exceed the typical nanostructure widths of 3D FEBID [ 1 , 3 ]. Interestingly, the halo diameter tends to increase for decreasing beam current.…”

“…The experiments started with reproducing the results from AgO 2 Me 2 Bu using a GIS heating temperature of 150 °C. In case of AgO 2 F 5 Prop, earlier studies [ 27 ] showed the successful deposition for a GIS temperature of 175 °C and a substrate temperature of 160 °C. To minimize unwanted thermal effects during and after deposition these temperatures were decreased to 140 °C GIS temperature and ca.…”

“…To address these issues AgO 2 Me 2 Bu was compared to another carboxylate compound. Silver pentafluoropropionate [Ag(µ-O 2 CC 2 F 5 )] 2 (AgO 2 F 5 Prop) provides for a similar evaporation temperature and electron-beam sensitivity but also for slightly higher gas flux and stability leading to deposits of high silver contents [ 27 ]. This makes it ideally suited for a comparative study elucidating the deposition behavior of such carboxylate compounds.…”

Pattern generation for direct-write three-dimensional nanoscale structures via focused electron beam induced deposition

“…Depending on the precursor used, and also on the chosen process parameters, a wide range of different materials can be obtained. On the one hand, polycrystalline metals can be realized, mainly of ferromagnetic type like Fe, Co or Fe–Co alloys [ 12 – 13 ] or noble metals, such as Pt, Au and Ag [ 14 – 16 ]. On the other hand, granular metals [ 17 ] but also various oxides and carbides in either amorphous or polycrystalline form [ 18 – 19 ] are accessible.…”