hd strain 3d strain metrology for electronic devices
TRANSCRIPT
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