genova july 2009 memristors
TRANSCRIPT
-
8/9/2019 Genova July 2009 Memristors
1/31
S.Carrara, EPFL Lausanne(Switzerland)
1
Genoa, 28Genoa, 28 JulyJuly, 2009, 2009
Fabrication of MemristorsFabrication of Memristors
with Polywith Poly--CrystallineCrystallineSiliconSilicon NanowiresNanowires
-
8/9/2019 Genova July 2009 Memristors
2/31
S.Carrara, EPFL Lausanne(Switzerland)
2
Talk OverviewTalk Overview
Concepts about Memristors Methods to fabricate poly-silicon nano-
wires
Structure of our nano-wire Memristors
The measured Memristor effect
Future Applications to Nano-Bio-sensing
-
8/9/2019 Genova July 2009 Memristors
3/31
S.Carrara, EPFL - Lausanne(Switzerland)
3
Memristors First ConceptMemristors First Concept
dq
dv
di
d
Four different circuit parameters:
dq
d
)(),(),(),( ttqtitv
di
dv
The missed equation!
R=
C
1=
L=
=
-
8/9/2019 Genova July 2009 Memristors
4/31
S.Carrara, EPFL Lausanne(Switzerland)
4
The Memristor requestThe Memristor request
Symmetry reasons seem demanding for Memristors
-
8/9/2019 Genova July 2009 Memristors
5/31
S.Carrara, EPFL - Lausanne(Switzerland)
5
Memristors First ConceptMemristors First Concept
So, M = R in
case of constantcharge!
( )[ ]( )
dq
qdtqM
=
( )
( )R
tdi
tdv=
( )
dtdq
dt
qd
=
Memristor depending on Charge Flux:
The usual Resistance:
( )
di
qdv=
While, M will be an R with memory
effect in case of varying charge!
)(qR=
-
8/9/2019 Genova July 2009 Memristors
6/31
S.Carrara, EPFL Lausanne(Switzerland)
6
The NameThe Name
MemoryResistor
MEMRISTOR
-
8/9/2019 Genova July 2009 Memristors
7/31
S.Carrara, EPFL Lausanne(Switzerland)
7
A two-terminals Memristor may be modeled bythrough two resistors as an element which vary the
resistance upon the applied voltage
Possible Memristor ModelPossible Memristor Model
-
8/9/2019 Genova July 2009 Memristors
8/31
S.Carrara, EPFL - Lausanne(Switzerland)
8
Memristors First ConceptMemristors First Concept
( ) )()(
1)(
tiD
twR
D
twRtv OFFON
+=
)()(
tiD
R
dt
tdw ONV=
= )(1)(
2tq
D
RRqM ONVOFF
)()( tqD
Rtw ONV=
More evident at nano-scale!
-
8/9/2019 Genova July 2009 Memristors
9/31
S.Carrara, EPFL Lausanne(Switzerland)
9
Current/Voltage CharacteristicsCurrent/Voltage Characteristics
Memristic effects are observable in I-V curves
as a memory of the channel doping in time
-
8/9/2019 Genova July 2009 Memristors
10/31
S.Carrara, EPFL Lausanne(Switzerland)
10
How to build a Memristor?How to build a Memristor?
These results serve as the foundation forunderstanding a wide range of hysteretic
current-voltage behaviour observed in manynano-scale electronic devices
[] until now no one has presented either auseful physical model or an example of a
memristor
-
8/9/2019 Genova July 2009 Memristors
11/31
S.Carrara, EPFL Lausanne(Switzerland)
11
How to build a Memristor?How to build a Memristor?
Memristors obtained by using organic materials
-
8/9/2019 Genova July 2009 Memristors
12/31
S.Carrara, EPFL Lausanne(Switzerland)
12
TopTop--Down Techniques forDown Techniques for
PolyPoly--silicon Nanosilicon Nano--WiresWires Based on patterning: Photolithography
Nanomold lithography
Stencil lithography
Spacer technique
Un-differentiated NWs
Moselund et al., TNANO07
500 nm
Melosh et al., Science03
Vasquez-Mena et al., Nano Letters08
5 m
Sacchetto et al., ESSDERC09 Choi et al., J. Vac. Sci. Tech. B03
-
8/9/2019 Genova July 2009 Memristors
13/31
S.Carrara, EPFL Lausanne(Switzerland)
13
BottomBottom--Up Techniques forUp Techniques for
PolyPoly--silicon Nanosilicon Nano--WiresWires
10 m 1 m
Whang, et al., Nano Letters03
Gudiksen et al., Nature02
Core
Shell
Shell
Cross-
section
Au
Lauhon et al.,
Nature02
Based on NW growth
NW can be differentiated: Radial doping
Axial doping
-
8/9/2019 Genova July 2009 Memristors
14/31
S.Carrara, EPFL Lausanne(Switzerland)
14
MultiMulti--Spacer PatterningSpacer Patterning
TechniqueTechnique
conformalpoly-Si layer
2. Conformal layer deposition
poly-Si
spacer
3. Anisotropic RIE etch
multi-spacers
4. Alternating iterations of 2-3
SiO2 sacrificial layer
caveSi substrate
1. Sacrificial layer
-
8/9/2019 Genova July 2009 Memristors
15/31
S.Carrara, EPFL Lausanne(Switzerland)
15
Fabrication Process: Frontend inFabrication Process: Frontend in
case of crosscase of cross--barsbars
SiO2 sacrificial layer
caveSi substrate
1. Sacrificial layer
conformalpoly-Si layer
2. Conformal layer deposition
poly-Si
spacer
3. Anisotropic RIE etch
upper
poly-Si
4. Definition of upper spacer
Cr/Ni Cr0.8 0.2
-
8/9/2019 Genova July 2009 Memristors
16/31
S.Carrara, EPFL Lausanne(Switzerland)
16
Sizes OverviewSizes Overview
Insulator
(SiO2)
Poly-Si
spacer
Si substrate
Dimensions are
not true to scale! Only frontend
processing is
depicted
Backend includes
passivation +
metallization
~ 400 nm~ 400 nm
~ 70 nm
~ 70 nm~ 20 nm
-
8/9/2019 Genova July 2009 Memristors
17/31
S.Carrara, EPFL Lausanne(Switzerland)
17
NanoNano-- toto MesoMeso--wires addressingwires addressing
Decoder
CrosspointsMesowires
Nanowires
Contact Group
Mesowire
VT2VT1 NanowireVA1 VA2 VA3 VA4
Nanowire
-
8/9/2019 Genova July 2009 Memristors
18/31
S.Carrara, EPFL Lausanne(Switzerland)
18
Fabrication ProcessFabrication Process
Frontend Passivation
BackendTesting
Definition of
crossing poly-Si
nanowire
Isolation of devices,
via opening for
metalization and
functionalization
Metalization: NiCror Cr/NiCr or Al
Current/Voltagemeasurements
-
8/9/2019 Genova July 2009 Memristors
19/31
S.Carrara, EPFL Lausanne(Switzerland)
19
Fabrication ResultsFabrication Results
The SEM imaging shows the quality of poly-siliconwires fabricated by using spacers technique
-
8/9/2019 Genova July 2009 Memristors
20/31
S.Carrara, EPFL Lausanne(Switzerland)
20
The registered I/V curves show memristic effects due to
a memory of the swept voltage windows
Current/Voltage CharacteristicsCurrent/Voltage Characteristics
Electrons de-trapping
Electrons trapping
Holes trapping
Holes de-trapping
-
8/9/2019 Genova July 2009 Memristors
21/31
S.Carrara, EPFL Lausanne(Switzerland)
21
Conductivity MechanismsConductivity Mechanisms
Both electrons and holes based conductivity isaffected by Memristor effect
-
8/9/2019 Genova July 2009 Memristors
22/31
S.Carrara, EPFL Lausanne(Switzerland)
22
The registered I/V curves show memristic effects due to
a memory of the swept voltage windows
Current/Voltage CharacteristicsCurrent/Voltage Characteristics
-
8/9/2019 Genova July 2009 Memristors
23/31
S.Carrara, EPFL - Lausanne(Switzerland)
23
)()()()()( EgEgEgEgEg GDGATDTA +++=
TD
v
W
EE
TDTD eNEg
=)(
2
)(
= GAGA
W
EE
GAGA eNEg
2
)(
= GDGD
W
EE
GDGA eNEg
TA
c
W
EE
TATA eNEg
=)(
Tail States Gaussian StatesAcceptors State Donors State
Simulations bySimulations by
driftdrift--diffusion modeldiffusion model
-
8/9/2019 Genova July 2009 Memristors
24/31
S.Carrara, EPFL Lausanne(Switzerland)
24
2D Simulations by Atlas follow the experimental
data accounting for negative trapped charges at thePoly-Si/SiO2 interface
-20 -10 0 10 20
10-11
10-10
10-9
10-8
10-7
Simulation
DrainC
urrent(A)
Gate Voltage (V)
Experiment
Simulations ResultSimulations Result
-
8/9/2019 Genova July 2009 Memristors
25/31
S.Carrara, EPFL Lausanne(Switzerland) 25
Future NanoFuture Nano--BioBio--sensingsensing
applicationsapplications
Frontend Passivation
BackendFunctionalization
Definition of
crossing poly-Si
nanowire
Isolation of devices,
via opening for
metalization and
functionalization
Metalization: NiCror Cr/NiCr or Al
Grafting of bio-markers
-
8/9/2019 Genova July 2009 Memristors
26/31
S.Carrara, EPFL Lausanne(Switzerland) 26
pH Dependent SensorpH Dependent Sensor
pH Sensor obtained by modifying Si oxide surface with 3-aminopropyltriethoxysilane yielding amino and silanol groups (actingas receptors) at surface
Patolsky et al., Nanowire-Based Biosensors, Analytical Chemistry, 2006, 4261-4269
Protonation/deprotonation altered charge density at surfacethereby changing conductance
For p-type FET: rising pH led to decreased positive chargeimplying increase in conductance
-
8/9/2019 Genova July 2009 Memristors
27/31
S.Carrara, EPFL Lausanne(Switzerland) 27
Detecting Single VirusDetecting Single Virus When virus binds to antibody receptor, conductance changes from
baseline value
When it unbinds, conductance returns to baseline value
Patolsky et al., Nanowire-Based Biosensors, Analytical Chemistry, 2006, 4261-4269
Results suggest the possibility to develop ultradense NW device where
minimum scale is set by size of virus
-
8/9/2019 Genova July 2009 Memristors
28/31
S.Carrara, EPFL Lausanne(Switzerland) 28
Concept in Memristors forConcept in Memristors for
NanoNano--BioBio--SensingSensing
The charging from molecules affects the Memristic
effects onto the poly-silicon channel
Back Gate
Nitride Passivation
Nano-wire channel
Top-gate
-
8/9/2019 Genova July 2009 Memristors
29/31
S.Carrara, EPFL Lausanne(Switzerland) 29
Memristors have been obtained by using poly-
silicon nano-wires
Poly-silicon nano-wires have been fabricated byusing spacer technique
Memristic effect has been registered in I/V
characteristics 2D simulations confirmed that Memristic effect is
due to charges trapped in the Channel/Gate
interface during deposition Future development will be in Nano-Bio-Sensing
ConclusionsConclusions
-
8/9/2019 Genova July 2009 Memristors
30/31
S.Carrara, EPFL Lausanne(Switzerland) 30
Thanks to CoThanks to Co--authorsauthors
M. Haykel Ben Jamaa
Julius Georgious
Nikolas Archontas
Giovanni De Micheli
-
8/9/2019 Genova July 2009 Memristors
31/31
S.Carrara, EPFL Lausanne(Switzerland) 31
Coordinates:Dr. Sandro Carrara Ph.D
Integrated Laboratory Systems
Swiss Federal Institute of Technology (EPFL)
CH-1015 Lausanne
Web: http://si2.epfl.ch/~scarrara/
email: [email protected]
Thank you for your attention!Thank you for your attention!