Electrons as “Invisible Ink”: Fabrication of Nanostructures by Local Electron Beam Induced Activation of SiO_x

Abstract

Beam me up: A novel two‐step process allows iron nanostructures to be generated locally on SiOx/Si at 300 K. The surface is first locally activated by an electron beam. Then the activated structures are exposed to [Fe(CO)5], which decomposes and grows autocatalytically to give pure Fe nanocrystals.

Investigation of proximity effects in electron microscopy and lithography

“…Recently, we demonstrated that the active sites on SiO x are oxygen vacancies generated by electron stimulated desorption. 18,19 This mechanism is also confirmed for the here investigated membrane covered with a native silicon oxide: it was found that a pre-irradiated membrane remains active towards Fe(CO) 5 decomposition for at least one day, with no significant differences of the observed iron deposits. This is a strong indication for a chemical modification (i.e., activation); if simple charging were to play a role, the activity should have decayed after one day.…”

“…[14][15][16][17] With electron beam induced surface activation (EBISA), we have recently introduced a FEBIP technique, where no FSE proximity effect occurs. 18,19 Figure 1 schematically depicts the ideal two step EBISA process: In the first step, the surface is irradiated and thereby locally activated with a focused electron beam; in the second step, it is exposed to the precursor iron pentacarbonyl, Fe(CO) 5 . On the activated sites, which are identified as oxygen vacancies, i.e., understoichiometric silica, 19 decomposition of Fe(CO) 5 at room temperature leads to the formation of Fe nuclei, which then grow autocatalytically upon prolonged precursor dosage to form clean, cubic Fe crystals, 18,19 corresponding to bcc aFe.…”

“…This result demonstrates that the EBISA concept can also be applied to natively oxidized SiN surfaces. 18,19 Since the iron deposits on both samples are expected to be very similar, the contrast of the different images was set such that they appear with similar brightness. The darker appearance of SiN-200 nm compared to SiN-bulk then is in line with the simulated lower BSE coefficient of the membrane.…”

Advances in gas-mediated electron beam-induced etching and related material processing techniques

“…These developments, and other examples of surface activation [91][92][93][94][95][96][97] and nanostructure editing through nonchemical pathways [99], highlight the wide diversity of processes that can be exploited by electron beam processing techniques. Furthermore, these recent applications illustrate the need for advances in predictive modeling of electron (and ion) beam restructuring of materials in both inert and reactive environments.…”

“…4(b)). The technique is a variant of similar methods used to fabricate chemically active surface regions [91][92][93][94][95][96][97], and electron irradiation methods used in surface chemistry studies of phenomena such as electron induced oxidation [98].…”