Formation of pure Cu nanocrystals upon post-growth annealing of Cu-C material obtained from focused electron beam induced deposition: comparison of different methods.

Aleksandra Szkudlarek,Stanislav Moshkalev,Rolf Erni,Czesław Kapusta,Alfredo Rodrigues Vaz,Andrzej Rudkowski,Ivo Utke,Yucheng Zhang

doi:10.3762/bjnano.6.156

Abstract

In this paper we study in detail the post-growth annealing of a copper-containing material deposited with focused electron beam induced deposition (FEBID). The organometallic precursor Cu(II)(hfac)2 was used for deposition and the results were compared to that of compared to earlier experiments with (hfac)Cu(I)(VTMS) and (hfac)Cu(I)(DMB). Transmission electron microscopy revealed the deposition of amorphous material from Cu(II)(hfac)2. In contrast, as-deposited material from (hfac)Cu(I)(VTMS) and (hfac)Cu(I)(DMB) was nano-composite with Cu nanocrystals dispersed in a carbonaceous matrix. After annealing at around 150–200 °C all deposits showed the formation of pure Cu nanocrystals at the outer surface of the initial deposit due to the migration of Cu atoms from the carbonaceous matrix containing the elements carbon, oxygen, and fluorine. Post-irradiation of deposits with 200 keV electrons in a transmission electron microscope favored the formation of Cu nanocrystals within the carbonaceous matrix of freestanding rods and suppressed the formation on their surface. Electrical four-point measurements on FEBID lines from Cu(hfac)2 showed five orders of magnitude improvement in conductivity when being annealed conventionally and by laser-induced heating in the scanning electron microscope chamber.

Highlights

Focused electron beam induced deposition (FEBID) is a direct maskless nanolithography technique, based on the local dissociation of adsorbates upon the irradiation with electrons [1]
In this paper we study in detail the post-growth annealing of a copper-containing material deposited with focused electron beam induced deposition (FEBID)
The molecules are delivered into the microscope chamber by a gas injection system (GIS) where they reversibly physisorb onto the substrate surface

Summary

Introduction

Focused electron beam induced deposition (FEBID) is a direct maskless nanolithography technique, based on the local dissociation of adsorbates upon the irradiation with electrons [1]. The molecules are delivered into the microscope chamber by a gas injection system (GIS) where they reversibly physisorb onto the substrate surface. The non-volatile fragments stick to the substrate surface whereas the volatile fragments are removed from the chamber by the pumping system. By controlling the beam scanning three dimensional structures of a complex shape can be created in a single direct-write deposition step onto planar or non-planar surfaces [2]. The feasibility of obtaining 3D nanostructures with a high aspect ratio makes FEBID suitable for fabrication of high resolution probes to scanning magnetic force microscopy (MFM) [17,18,19]

Methods

Results

Conclusion