HD STRAIN 3D strain metrology for electronic devices
Journées Nationales en Nanosciences et Nanotechnologies 2012
CEMES Toulouse
LETI Grenoble
Crolles Grenoble
Develop Dark-Field Electron Holography (HoloDark) for Strain Metrology in Devices • Methodology: 2D → 3D measurements • Instrumentation: brighter electron sources, in-situ experiments • Characterisation: model → industrial specimens
A
Conventional holography
incident beam
incident beam
transmitted beam
holographic fringes
Si Si1-xGex
source drain
gate
MOSFET Transistor
Strained Si
Nitride layer
SiGe SiGe
-3% 3% εxx 200 nm
s-Si Si1-xGex
Dark-Field Electron Holography
M J Hÿtch, F Houdellier, F Hüe, E Snoeck, Nature 453, 1086 (2008)
Strained Silicon
• Strained silicon channel • Strain engineering methods include embedded sources and strain layers; technology which is industrial standard • Straining silicon increases carrier mobility (electrons or holes)
Strain Mapping
need for measurement
reliable and robust technique for strain measurements
Contact: Martin Hÿtch [email protected]
Tomography
International Patent Application: PCT N° PCT/FR2008/001302 (CNRS)
F Hüe, M J Hÿtch, F Houdellier, H Bender, A Claverie, APL 95, 073103 (2009)
Finite Element Model • New technique interferes diffracted beams from unstrained (A) and strained (B) regions • Advantages include: µm-field of view, high spatial resolution and high precision
M J Hÿtch et al. Physica Status Solidi A 208, 580 (2011) HoloDark 1.0 software (HREM Research Inc.) by M J Hÿtch, C Gatel, K Ishizuka
HD HB α=40°
0 50 100 150 200-2
0
2
4
6
8
10
12
14
16
Y
X ( nm )
ampl phase
0 20 40 60 80 100 120 140 160 180 200
0
2
4
6
8
10
12
14
16
ampli
tude
X ( nm )
Exp Simu
Experiment α=34°
M J Hÿtch, F Houdellier, F Hüe, E Snoeck, Ultramicroscopy 111 1328-1337 (2011)
Holographic fringes
Incident beam
Diffracted beam B
Areference
Diffracted beam A
Bstrained
Biprism
CG φφ +Cφ
Gφ
α=2° α=15° α=40.5°
Dark field hologram Phase image Amplitude image
In situ TEM measurements and finite element modelling
Al
Si
SiO2 Diamond tip Bulk Si
Indentation mark in the silica
Ø Slip-traces + stereographic projection map -> slip plane (111) Ø Cross-slip event -> Burgers vector b=[01-1] Ø Resolved shear stress Ø Applied force T=[103] -> Schmid factor Ø Shear stress
τ = µ b / R = 200 MPa
Brighter electron source
F Houdellier and M Monthioux, French Patent Application, FR 10 03696, 2010 (CNRS)
F Houdellier, A Masseboeuf, M Monthioux, M J Hÿtch, Carbon 50 (2012) Development of a New Cold Field-Emission Gun for Electron Holography.
Carbon tip W[310] tip
W[310] tip
Carbon tip
Emission current = 8 µA Exposure = 1 s
C2 aperture = 50 µm
CCnT
CCnT
ref.
meas. biprism
d +γ→ work function φ
I = A1.5×10−6
φEloc2 exp 10.4
φ
#
$%%
&
'((exp −
6.44×109φ1.5dγV
#
$%
&
'(
Eloc = γE0 = −γVd
γ = 21.5φ = 4.8± 0.3 eVd = 680 nm
Au anode
Etched W wire
Carbon cone nanotip
V
i
10 μm
d
L de Knoop, S Reboh, M Legros
E Javon, C Gatel, A Lubk, M J Hÿtch
L de Knoop, F Houdellier, C Gatel, A Masseboeuf, M
Monthioux, M J Hÿtch
Anode 80 V
CCnT
Phase ϕ =CE V dlbeampath∫
γ =Eloc
E0=2.580.12
= 21.5
Fowler-‐Nordheim equaCon:
Anode 80 V
Cross slip event
Al
Si
SiO2
Bulk Si
0 GPa
2 GPa
S = cos T,b( ) ⋅cos T, (111)( ) = 0.48σ = τ / S = 400 MPa
Slip trace
R
Ø External stress with 150 µN applied force -> 2-300 MPa in Al layer
Simulation
0 20 40 60 80 100 120 140 160 180 200 220-6
-4
-2
0
2
4
6
8
10
12
14
Am
plitu
de
X ( nm )
HB HD
a) TEM micrograph b) Experimental strain map c) FEM of strain
a)
b)
c)
01/01/2009 -> 30/09/2013
Anode 80 V
