Response under low-energy electron irradiation of a thin film of a potential copper precursor for focused electron beam induced deposition (FEBID).

Leo Sala,Anne Lafosse,Iwona B Szymańska,Céline Dablemont,Lionel Amiaud

doi:10.3762/bjnano.9.8

Abstract

Background: Focused electron beam induced deposition (FEBID) allows for the deposition of free standing material within nanometre sizes. The improvement of the technique needs a combination of new precursors and optimized irradiation strategies to achieve a controlled fragmentation of the precursor for leaving deposited material of desired composition. Here a new class of copper precursors is studied following an approach that probes some surface processes involved in the fragmentation of precursors. We use complexes of copper(II) with amines and perfluorinated carboxylate ligands that are solid and stable under ambient conditions. They are directly deposited on the surface for studying the fragmentation with surface science tools.Results: Infrared spectroscopy and high-resolution electron energy loss spectroscopy (HREELS) are combined to show that the precursor is able to spontaneously lose amine ligands under vacuum. This loss can be enhanced by mild heating. The combination of mass spectrometry and low-energy electron irradiation (0–15 eV) shows that full amine ligands can be released upon irradiation, and that fragmentation of the perfluorinated ligands is induced by electrons of energy as low as 1.5 eV. Finally, the cross section for this process is estimated from the temporal evolution in the experiments on electron-stimulated desorption (ESD).Conclusion: The release of full ligands under high vacuum and by electron irradiation, and the cross section measured here for ligands fragmentation allow one to envisage the use of the two precursors for FEBID studies.

Highlights

The high electrical conductivity of copper makes it a material of choice for the development of electronic devices at the nanometre scale
57b, 63c 74b, 61d 90b, 86c 86-100c, 87d 106b; 100–110c, 116–125e 124b, 130c, 126e 128–165b, 149–153c, 111–161f 174b, 180c, 176d 180g 189b 206b, 219c ν(C=O), 192d 367b 377–381b aν,νs,νa: stretching, symmetric, antisymmetric, δ: angular deformation, ρ: rocking; bVT-IR, [Cu2(t-BuNH2)2(μ-O2CC2F5)4], [Cu2(EtNH2)2(μ-O2CC2F5)4] [7,8]; cHREELS (5eV, specular), solid CF3COOH condensed at 30 K [10]; dHREELS, C6H5COO− chemisorbed on Cu (
The present study is our first attempt to use surface science tools, usually dedicated to the study of low-energy electron induced processes, to gain insights on dissociation processes induced on potential precursors for Focused electron beam induced deposition (FEBID)

Summary

Introduction

The high electrical conductivity of copper makes it a material of choice for the development of electronic devices at the nanometre scale In such applications, the conductivity of the deposit and its thermal behaviour strongly depend on the achieved purity, which still needs to be improved with standard techniques [1,2]. A new group of copper precursors [Cu2(R′NH2)2(μ-O2CR)4] synthetized with two copper(II) cations has been designed by the co-authors at Nicolaus Copernicus University in Toruń, Poland, for chemical vapor deposition (CVD) [6,7,8] Among these complexes, two different compounds, [Cu2(EtNH2)2(μ-O2CC3F7)4] and [Cu2(EtNH2)2(μ-O2CC2F5)4] (Figure 1) will be studied in the present paper and hereafter named as compound A and compound B, respectively. They are directly deposited on the surface for studying the fragmentation with surface science tools

Methods

Results

Conclusion