LaWaTAP

Tomographie atomique: De l’instrumentation aux Nanosciences
Didier Blavette
E. Cadel
R. Lardé
P. Pareige
A. Vella
D. Mangelinck
B. Deconihout
F. Vurpillot
A. Bostel
O. Cojocaru-Mirédin
M. Gilbert
A. Grenier
La tomographie atomique laser
•La tomographie atomique: les bases
• Application aux nanomatériaux, multicouches…
• L’émergence de la sonde laser
• Ouverture aux semiconducteurs et la nanoélectronique
• Multicouches magnétiques tunnel
Groupe de Physique des Matériaux - University of Rouen- France
Al-Mg-Si aged 30’ at 205°C
<001> β’’ neddles
The Tomographic AtomProbe (1993)*
Detector
tip
R = 50 nm
Ni, Cr + Al
* D. BLAVETTE, A. BOSTEL, J. M. SARRAU, B. DECONIHOUT and A. MENAND
An atom-probe for three dimensional tomography, Nature 363 (1993) 432-435
Cr
Al
0,700µs
Al
The Tomographic AtomProbe (1993)*
Cr
Al
0,700µs
1,000µs
Cr
The first TAP detector: Electron charge cloud centroiding (over 100 anodes!)
> ion impact position
A simple point projection microscope
Surface position (Xp,Yp) ?
Xp = X/G
Yp = Y/G
G = (m+1)L/R
R ≈ V/Eβ
Eβ ~23v/nm for NiCrAl
Analysed area φ2
φ = D/G ~ 10nm
D detector size (10 cm)
Atmospheres de Cottrell
riches en bore dans FeAl
(100) planes
Science (1999), courtesy E. Cadel
TbCo2 (20nm)/Fe (25nm) magnetostrictive multilayers
Fe
TbCo2
Courtesy A. Grenier, GPM
TbCo2 is a hard magnetic amorphous phase whereas Fe is soft
The investigation of interfaces in TbCo2 / Fe magnetostrictive multilayers
Co
Tb
concentration (at %)
Fe
100
80
Fe
Co
Tb
O
60
40
20
0
0
10
Abrupt interface
20
30
40
50
depth (nm)
(Fe on Tb2Co)
diffused interface
(Co on Fe)
Tb profile is abrupt to
both interfaces
10 × 8 × 76 nm3
Miscibility of Co-Fe
60
A new generation of 3DAP: A laser assisted TAP (LaWaTAP)
Tsong and Kellog, pionners in the introduction of ns pulsed lasers in atom probe (1978)
500 µm
Groupe de Physique des Matériaux - University of Rouen- France
fs laser assisted evaporation of a tungsten tip
Analysis of intrinsic Si with the LaWaTAP
Ga
Si
Preparation of tips from silicon wafers using FIB
Silicon: impurety concentration 1011.cm-3 Resistlivity = 104 Ω .cm at 300K
10-8
10--6
metals
10-4
102
semiconductors
Analysis carried out at 60 K
105
intrinsic Si
109
insulators
Ω.cm
Groupe de Physique des
Matériaux - CNRS
LaWaTAP
The LAWATAP
PSD (80 mm)
X
Y
area of analysis
Up to 100×100 nm2
S-pulse laser unit : 0-100 µJ/pulse, 10 kHz,
T-pulse laser
: 0-1 µJ/pulse, 1 MHz,
1 inch FIM Stage
HV-Pulsing by extraction electrode
40°
11 cm
1690mm
900mm
timing
LaWaTAP: a larger analysed volume
7x7x20 nm
Yesterday
Now !!
(10Matoms)
40 × 40 ×200 nm 3
Super alliage à base de Nickel
The nature of NiSi contacts in nano-MOSFET transistors*
E. Cadel (GPM), D. Mangelinck (L2MP - Marseille)
Image of a MOSFET transistor
• NiSi phase that forms by reactive diffusion between Ni and Si (drain) has a good
electrical conductivity. Pt addition increases its stability.
• Nature of phases in as-deposited contacts and distribution of Pt?
* See also papers of Thompson et al. - IMAGO - investigation of heat treated Ni contacts on Si
Ni/Si
SEM image (E. Cadel, GPM)
Focused ion beam
milling (FIB)
Ni(5%Pt)Si- thermal treatment, 290°C - 1h
Ni
60 nm
Ni2Si
Si
Ni+Si
Pt
16 nm
50 nm
Pt
Ni
Si
NiSi
Pt segregation to Ni/Ni2Si interface: a snowplow effect (O. Cojocaru-Mirédin et al. Scripta
Mater. (2007)
Investigation of semiconductor nanowires
InAs nanowire terminated by gold
(nucleating growth agent
(D.N Seidman group,
NorthWestern)
Perea et al, Nano Letters, vol 6, page 181, 2006
The bottom-up approach in
nanoelectronics
MgO/Fe Tunnel junctions (Laser:1030 nm, 450 fs, E<10 µJ)
Au
4nm
40 nm
200
nm
Mg
High impedance device
O
(H=0 > AF coupling
between Fe layers)
MgO 2 nm
External field H:
Low conductivity
Si
Fe
(tunnel effect)
Application to MRAM
45.000.000 atoms
T. Al Kassab, F. Vurpillot, Collab univ. Gottingen
Investigation of SiGe implants
LaWaTAP versus SIMS
(L. Renaud, CAMECA)
Si cap (10nm)
SiGe(5%,10nm)
SiGe(10%,10nm)
SiGe(15%,10nm)
SiGe(18%,14nm)
Si substrate
Depth profiling direction
20
18
Pt
Ga
Ge
C,
Concentration (atomic %)
16
14
12
10
8
6
4
2
0
0
10
20
30
40
50
60
70 80 90
Depth (nm)
100 110 120 130 140 150
Concentration (atomic %)
Atom Probe tomography versus SIMS
20
18
16
14
12
10
8
6
4
2
0
LA-WATAP
SIMS
0
20
40
60
80
Depth (nm)
100
120
Results are similar but :
¾ LA-WATAP : Higher depth resolution
¾ SIMS : better statistic for composition measurement
140
The Large angle laser assisted Tomographic Atom Probe
The development of LaWaTAP in Nanoscience
The main advantages of the femtosecond pulsed laser (LaWaTAP):
Analysis of non metallic materials: semiconductors, oxydes
Low energy deficits: high mass resolution (~ 1000)
Analysis of brittle materials
Successful experiments were made on a wide range of nanomaterials :
Metals: AlMgSi, brittle irradiated steels, amorphous FeBSi, TiAl, Inconel, Zircalloy,
NiCrAl, Nanocristalline materials, multilayers…
Ceramics (Supraconductors, PrCaNiMnO3 manganites...), iron oxides
Silicon: intrinsic Si, doped Si, two-phase implanted (Co) Silicon, Si nanowires, NiSi...