Co-deposition from W(CO)6 and C10H8 by Focused Ion Beam
I. Serrano-Esparza1,2, R. Córdoba3, J.J.L. Mulders4, M.R. Ibarra2,3, J.M. De Teresa1,2,3
1
Instituto de Ciencia de Materiales de Aragón (ICMA)-CSIC-Universidad de Zaragoza,
Zaragoza, 50009, Spain
2
Departamento de Física de la Materia Condensada – Universidad de Zaragoza, Zaragoza,
50009, Spain
3
Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA),
Universidad de Zaragoza, Zaragoza, 50018, Spain
4
FEI Electron Optics, Eindhoven, 5600 KA, The Netherlands
1. Abstract
The Multi-Chem gas injection system from FEI allows inserting six different gases inside the
vacuum chamber of a Dual Beam system through a single needle. We have used the Multi-Chem
to perform Focused Ion Beam Induced co-deposition (FIBID) of C-W deposits using a
simultaneous flux of W(CO)6 and C10H8 precursor materials inside the main chamber of a
Helios-650. The partial pressure inside the chamber is controlled individually for each precursor
by changing the duty cycle of the respective pulse width modulation valve. The dependence of
the partial pressure (∆P) inside the vacuum chamber, and hence the incoming molecular flux (J)
[1][2], as a function of the valve duty cycle (D) for W(CO)6 and C10H8 is shown in Fig 1.
Changing the duty, and hence the molecular flux, we obtained different deposition rates R,
which tend to saturation at high ∆P.
In order to explore the feasibility of Focused Ion Beam Induced co-deposition of C-W
deposits using simultaneous W(CO)6 and C10H8 precursor gases with the Multi-Chem, we grew
1×1 µm2 deposits varying the respective gas fluxes. Unexpectedly, we found that the codeposition rate was not the sum of the deposition rate of each gas separately, but in general
much lower, as shown in Fig 2. Moreover, cross-sectional SEM images of the C-W co-deposits
showed that they were quite heterogeneous; EDS measurements indicate that W-rich regions
segregate from C-rich regions. This behaviour might be explained in terms of a subtle
competition between the two precursor gases plus the milling effects produced by the focused
Ga-ions beam. Our results are a first step towards the control and understanding of co-deposition
by Focused Ion Beam.
P (mbar)
2. Images
1x10
-5
8x10
-6
6x10
-6
4x10
-6
2x10
-6
C10H8
W(CO)6
0
0
20
40
60
D (%)
80
100
Figure 1. Dependence of the chamber partial pressure (∆P) as a function of the valve duty cycle (D) for W(CO)6 and
C10H8 precursors.
12
DW = 5%
DC = 10 - 100%
DC = 0 - 100% D = 10%
W
10
DC = 0 - 100%
DW= duty 15%
R (nm/s)
8
DW = 5 - 100%
DC = 0 - 100%
6
4
DW = 20 %
2
DC = 0 - 100%
0
0.0
2.0x10
-6
-6
4.0x10 6.0x10
P (mbar)
-6
-6
8.0x10
1.0x10
-5
Figure 2. Deposition rate (R) as a function of the partial pressure (∆P) for single adsorbate model and for twoadsorbate model.
3. References
[1]
L. Bernau, M. Gabureac, R. Erni, and I. Utke, “Tunable nanosynthesis of composite materials by electronimpact reaction.,” Angew. Chem. Int. Ed. Engl., vol. 49, no. 47, pp. 8880–4, Nov. 2010.
[2]
I. Utke, P. Hoffmann, and J. Melngailis, “Gas-assisted focused electron beam and ion beam processing and
fabrication,” J. Vac. Sci. Technol. B Microelectron. Nanom. Struct., vol. 26, no. 4, p. 1197, 2008.