The radiation chemistry of focused electron-beam induced etching of copper in liquids

Abstract

Well-controlled, focused electron-beam induced etching of copper thin films has been successfully conducted on bulk substrates in an environmental scanning electron microscope by controlling liquid-film thickness with an in situ correlative interferometry system.

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

“…The deposit will build up by nucleation and growth of copper atoms and clusters. Detailed analysis of the reactions to deposit copper from aqueous copper solutions and, electron beam spatial energy deposition in the liquid in vicinity of water vapor using Monte Carlo simulations are presented in [29] and [30] respectively. Moreover, in Figure 4 it is shown that a pattern of 200 nm pitch nested lines deposited at a relatively high dose of 20 µC/cm, are merged with a flat top surface.…”

“…The deposit will build up by nucleation and growth of copper atoms and clusters. Detailed analysis of the reactions to deposit copper from aqueous copper solutions and, electron beam spatial energy deposition in the liquid in vicinity of water vapor using Monte Carlo simulations are presented in [29] and [30] respectively.…”

“…Specifically, pattern reproducibility and consistency as well as electron scattering events are affected directly by liquid thickness. [27][28][29][30][31] However, controlling the thin liquid film in a partial vacuum has remained a serious challenge. Previously, we used shallow microwells to produce a meniscus which yielded a thin liquid layer close to the centre of the well.…”

“…Liquid film thickness is critical for understanding and controlling the LP-FEBIP. Specifically, pattern reproducibility and consistency as well as electron scattering events are affected directly by liquid thickness [27][28][29][30][31]. However, controlling the thin liquid film in a partial vacuum has remained a serious challenge.…”

Nanoscale focused electron beam induced etching of nickel using a liquid reactant

“…With regard to etching, the earliest study reported liquidphase focused electron beam induced etching (LP-FEBIE) of silicon nitride windows of a closed liquid cell using 1 wt% KOH (aq) [6,21]. In more recent work, copper etching on bulk substrates with no liquid cell was achieved using aqueous sulfuric acid as a liquid reactant [22,23]. The process demonstrated excellent selectivity and no damage to the underlying layers.…”