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 hytch@cemes.fr

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