final presentation - graduation project ebid
TRANSCRIPT
Electron Beam Induced Depositioninvestigating a new tool for Spintronics
Graduation presentation
Michael Beljaars
Hans Mulders, FEI Company
Reinoud Lavrijsen, TU/e
Henk Swagten, TU/e
Physics of Nanostructures (FNA)
Spintronics
Electron• charge• spin
e-
spin + electronics =
Spintronics!
Electron Beam Induced Deposition
substrate
needle
electron beam
precursor
vacuum environment
EBIDEBIDEBIDmultiple passes
element of interest
contamination
precursor fluxdeposition
direct structuring deposition of arbitrary material resolution down to 10 nm
Possibilities of EBID
EBID deposited iron magnets
substrate
• What equipment is used ?• Which precursors are investigated?
Deposition yieldComposition
Magnetic properties
Shape analysis
• How fast can we make a deposition?• How much iron is in the magnet?• How strong is the magnet?
• How well defined is the shape of the deposition?
FEI dual beamInvestigated iron precursors
iron
NZ
FEI dual beam
view inside chamberoutside view
electron beam
sample holder
needle
vacuum chamber
Investigated iron precursors
Tri-iron-dodeca-carbonyl Di-iron-nona-carbonyl
Fe3(CO)12 Fe2(CO)9
low gas flux high gas flux
Deposition yield
substrate
deposition
beam
VY
I t
deposition volume V
high gas flux
low gas flux
Composition
iron
carbon
oxygen
high gas flux
low gas flux
Magnetic properties
AFMheight image
MFMmagnetic image
NZ
5 µm
Shape analysis
substrate
deposition
3D AFM image
Surface processes
substrate
needle
adsorption
desorption
diffusion
vacuum environment
high N
low N
surface occupation N
EBID and surface occupation
substrate
deposition
electron beamdepositiondeposition
adsorption desorption
diffusion diffusion
N
N
heig
ht
Simulation
• Adsorption• Desorption
• Diffusion
• Deposition
adsE
diffE
adsorptiondesorption
distance to surface
pote
ntia
l
adsEdiffE
distance along surface
pote
ntia
l
diffusion
Experiment and simulation
heig
ht (
a.u.
)
length (a.u.)
width (a.u.)
experiment simulation
Waiting time experiment
substrate
deposition
5
10
15
20
25
30
35
0 ms15 ms40 ms
0 1 2 3 4 50
heig
ht (
nm)
width (μm)1 1.2 1.4 1.6
0
5
10
15
20
25
30
35
width (μm)
high surface occupation
low surface occupation
diffusion
spiralingdeposition
inner to outer
Pass time 45 ms
Conclusions
• Depositions of two iron precursors characterized• Yield low yield for Fe3(CO)12, average yield for Fe2(CO)9
• Composition very high iron content (up to 60 atomic %)
• Magnetic properties indications for ferromagnetic behavior
• Deposition shapes understood• Model developed• Experimental results qualitatively explained by model
Outlook
• Model enhancement• determine energy barriers involved in surface processes• quantitative description of deposition process
• Deposition properties• further enhance composition• extensive magnetic characterization• investigate electrical conductance
Electron Beam Induced Deposition
substrate
needle
electron beam
Magnetic properties
FEI dual beam
Investigated iron precursors
Tri-iron-dodeca-carbonyl Di-iron-nona-carbonyl
Fe3(CO)12 Fe2(CO)9
methanol
Deposition - Diffusion regimes
N
N
heig
hthe
ight
Giant Magneto Resistance
spin + electronics = Spintronics!
Electron – Solid interactions
substrate
electron beam
secondary electrons
Increasing beam energy
0 1 2 3 4 50 . 0
0 . 5
1 . 0
1 . 5
2 . 0
2 . 5
SE y
ield
(SE
/ P
E)
elect ron beam energy (keV )
area of maximum SE yield
Electron Beam Induced Deposition
substrate
needle
electron beam
precursor
adsorption
desorption
precursor flux
diffusion
vacuum environment
Electron – Solid interactions
substrate
electron beam
Electron – Solid interactions
substrate
electron beam
secondary electrons
Increasing beam energy
0 1 2 3 4 50.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
SE
yie
ld (
SE
/ P
E)
P E energy (keV )
Outline
• Introduction to Spintronics• Electron Beam Induced Deposition• Investigated iron precursors• Characterization of depositions• Deposition geometry
• Conceptual model• Experiment
• Conclusions• Outlook
Deposition yield
substrate
deposition
beam
VY
I t
Beam current (nA)
Yie
ld (
μm
3 nC
-1)
deposition volume V
high gas flux
low gas flux
EBID deposited magnets
substrateEBIDEBIDEBIDmultiple passes
• What equipment is used ?• Which precursors are investigated?
Deposition yieldComposition
Magnetic properties
Shape analysis
• How fast can we make a deposition?• How much iron is in the magnet?• How strong is the magnet?
• How well defined is the shape of the deposition?
FEI dual beamInvestigated Iron precursors