Room Temperature Direct Electron Beam Lithography in a Condensed Copper Carboxylate

Abstract

High-resolution metallic nanostructures can be fabricated with multistep processes, such as electron beam lithography or ice lithography. The gas-assisted direct-write technique known as focused electron beam induced deposition (FEBID) is more versatile than the other candidates. However, it suffers from low throughput. This work presents the combined approach of FEBID and the above-mentioned lithography techniques: direct electron beam lithography (D-EBL). A low-volatility copper precursor is locally condensed onto a room temperature substrate and acts as a positive tone resist. A focused electron beam then directly irradiates the desired patterns, leading to local molecule dissociation. By rinsing or sublimation, the non-irradiated precursor is removed, leaving copper-containing structures. Deposits were formed with drastically enhanced growth rates than FEBID, and their composition was found to be comparable to gas-assisted FEBID structures. The influence of electron scattering within the substrate as well as implementing a post-purification protocol were studied. The latter led to the agglomeration of high-purity copper crystals. We present this as a new approach to electron beam-induced fabrication of metallic nanostructures without the need for cryogenic or hot substrates. D-EBL promises fast and easy fabrication results.

In Situ Time-of-Flight Mass Spectrometry of Ionic Fragments Induced by Focused Electron Beam Irradiation: Investigation of Electron Driven Surface Chemistry inside an SEM under High Vacuum

“…Metalorganic precursors, such as MeCpPtMe 3 [ 55 , 56 ] and W(CO) 6 [ 57 , 58 ], as a condensed resist, were used in cryogenic conditions due to their high volatility. Non-volatile room-temperature metalorganic resist lithography so far comprises compounds of Pd [ 27 , 59 , 60 ], Ir [ 61 ], Au [ 26 , 62 ], Ag [ 63 ], and Cu [ 64 ]. Gas-assisted FEBID employs volatile precursors continuously supplied to the substrate via a gas injection system.…”

Cryo-Focused Ion Beam-Induced Deposition of Tungsten–Carbon Nanostructures Using a Thermoelectric Plate

“…The precursor overabundance allows for the usage of reduced ion doses, which result in much shorter processing times [11]. A functionally similar approach that makes use of a focused beam of electrons instead of ions has also been successfully demonstrated in the growth of platinum [12,13] and copper [14] nanostructures.…”

Limiting regimes for electron-beam induced deposition of copper from aqueous solutions containing surfactants

“…Focused electron beam induced processing (FEBIP) is a versatile technique that allows the direct deposition and etching of nanostructures. FEBIP provides a means of nanoscale, 3D rapid prototyping, and it has traditionally been conducted using gaseous precursors and etchants [1][2][3][4][5][6][7][8][9][10].…”