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ANR/P2N2013 NOODLES 13/01/2016 1

NOODLES

NanOdevice mODeling for Low

powEr applicationS

Web site: noodles.minatec.grenoble-inp.fr

ANR/P2N2013 NOODLES 13/01/2016 2

Project description

N° ANR: ANR-13-NANO-0009

Acronyme : NOODLES

Date de commencement: 03/03/2014

Durée du projet: 42 mois

Partenaires :

1. IMEP-LAHC, Grenoble, coordination du projet

2. IEMN, Lille

3. CEA-INAC, Grenoble

4. IM2NP, Marseille

5. ST Microelectronics, Crolles

6. CEA-LETI, Grenoble

ANR/P2N2013 NOODLES 13/01/2016 3

Context: CMOS Power crisis

• Vth cannot be longer decreased, so VDD has almost stopped to scale

down

• Importance of power efficiency

• The optimal performance/consumption trade-off is particularly

difficult for LOP devices used in all mobile applications

ANR/P2N2013 NOODLES 13/01/2016 4

Objectives

Main goal: to identify the best device and

material combination for LOP applications

Approach: Semi-analytical models and predictive multi-

scale simulations ranging from full-quantum to semi-

classical approaches

Scientific issues to be addressed

– Self-heating effects and hot-carriers transport

– Extra-channel parasitic effects

– Assessment of III-V semiconductors (MOSFETs and

TunnelFETs)

ANR/P2N2013 NOODLES 13/01/2016 5

Description of the tasks

ANR/P2N2013 NOODLES 13/01/2016 6

Task schedule

Schedule of the project Year 1 Year 2 Year 3 Year 4 Involved

partners * T1 T2 T3 T4 T1 T2 T3 T4 T1 T2 T3 T4 T1 T2 T3 T4

1 Accord de consortium ■ ■

2 Task 2: Self-heating and

hot carriers dynamics

IEMN, IMEP-

LAHC,LETI, INAC,

IM2NP

T 2A: Atomistic theory of

hot-carrier dynamics ► IEMN, INAC

T 2B: Calculation of

thermal properties at the

atomic scale

►

IEMN, IMEP-LAHC

T 2C: Development of a

common module for the

3D heat equation

■

►

IMEP-LAHC, INAC,

LETI, IM2NP

3 Task 3: Influence of

extra-channel physics

INAC, ST, LETI,

IM2NP

T 3A : Injection from

metallic contacts ► INAC, IM2NP, ST

T 3B: Scattering in

highly doped regions ■ INAC, IM2NP, STM

T 3C: Optimization of the

contact geometry and

doping profile ■ INAC, LETI, IM2NP

▲: Initially scheduled ►: Under-progress : abandoned ■ : realized

ANR/P2N2013 NOODLES 13/01/2016 7

Task schedule

T 3D: Exploratory study

of transient regimes

within the NEGF ► IM2NP

4

Task 4: Alternative

channel materials for

LOP applications

IM2NP, IMEP-

LAHC,LETI,

INAC,STM

T 4A: K.p and Kubo-

Greenwood model

parameterizations

■ INAC, LETI, STM,

IMEP-LAHC

T 4B: Transport

properties of III-V

material NW and films w.

r. t. Si and Ge

■

►

IMEP-LAHC,

IM2NP, INAC, STM

T 4C:Transport

properties of steep-slope

devices based on III-V

►

IMEP-LAHC,

IM2NP

5

Task 5: Analytical

equations for compact

modeling

IMEP-LAHC, INAC,

STM, IM2NP

T 5A : Calibration of

analytical models for

rapid simulations ■ ► ► IMEP-LAHC, INAC

T 5B: Simulation of

simple circuits via

analytical models ► STM

T 5C: Study of quantum

transport in two

transistors described

with the NEGF

► IM2NP


ANR/P2N2013 NOODLES 13/01/2016 8

Task schedule

6 Task 6: Comparison with

characterization data STM, LETI, INAC

T 6A: Experimental

validation ■ ► STM, LETI, INAC

T 6B: Predictive

simulation for the design

of new devices

► ► ► INAC, LETI, STM


ANR/P2N2013 NOODLES 13/01/2016 9

Task 2

Self-heating and hot carrier

dynamics

ANR/P2N2013 NOODLES 13/01/2016 10

Thermal conductivity and interface resistance

• Method : Approach-to-Equilibrium Molecular Dynamics

• Exponential decay (τ) in the approach

to equilibrium

• Hence Kth is extracted from τ using

solution of the heat equation

IEMN

ANR/P2N2013 NOODLES 13/01/2016 11

3D electro-thermal quantum simulations

• Methodology: Valence

force model + NEGF for

electron and phonon

transport

• Quantum expression to

couple the Heat equation

with NEGF equations

• Increase of self-heating

effects induced by SR

IMEP-LAHC

top of the barrier

M. Pala et al., JAP (2015)

ANR/P2N2013 NOODLES 13/01/2016 12

0

10-9 W/nm3

Power density

TSi = 6 nm

Lg = 24 nm

burried oxide

• NEGF coupled with the Poisson heat equation

Outgoing current spectrum per layer

300 K

320 K Temperature

NEGF/heat equation coupling

Vgs = 1 V

Vds = 0.9 V

1st

subbands

energies

Self-heating in FDSOI devices LETI, INAC

ANR/P2N2013 NOODLES 13/01/2016 13

Relaxation of a hot electron in Si nanowire / bulk

Time step = 0.1 fs

Bulk

NW

Methodology: atomistic theory

- Electronic states: tight-binding

- Phonons: valence force field

- Scattering rates: Fermi golden rule

- All scattering processes included

- Monte Carlo simulation of the relaxation

Energy of the phonons involved in

the relaxation

>0 = Emission

ANR/P2N2013 NOODLES 13/01/2016 14

Efficient treatment of phonon scattering via the

low-order approximation

• The Problem of Self-Consistent Born Approximation:

Computationally expensive

• Lowest-order approximation + the use of analytic continuation to

reconstruct divergent series can provide a more efficient

alternative to SCBA

H. Mera et al., Phys. Rev. B (R) 88, 075147 (2013)

IM2NP

Optical Phonon Interaction - Mop = 10×10-4 [eV2]

ANR/P2N2013 NOODLES 13/01/2016 15

Inclusion of LOA in OMEN

• N-type Si NW

SCBA needs 50 number of

iterations on average

ANR/P2N2013 NOODLES 13/01/2016 16

On-going activities in task 2

• Study of the proper boundary conditions and dielectric environment

in the solution of the 3D Heat equation

• Include different temperatures for acoustic and optical phonons

• Coupling of e-e scattering for hot electrons

• Evaluation of thermal resistances between Semiconductor and

Oxide to be transferred in the electro-thermal calculations

• Accurate reproduction of large scale thermal simulations

power density: temperature:

ANR/P2N2013 NOODLES 13/01/2016 17

Task 3

Influence of extra channel

physics

ANR/P2N2013 NOODLES 13/01/2016 18

Rc

Contact resistances in planar FDSOI & trigate

technologies

• Contacts are expected to be the major contributor to

the resistance of sub 30 nm technologies at low field.

• NEGF provides an explicit description of surface

roughness and charge impurities.

• Methodology : Numerical transmission line method.

INAC, STM,

LETI

ANR/P2N2013 NOODLES 13/01/2016 19

Vgt = 0.69 V

• Contact resistance (red) is much larger than

the ballistic resistance (black) and a significant

fraction of the total resistance of a 30 nm long

device (blue)

• HDD/LDD resistances limited by the (poor)

charge control under the spacers

Contact resistances in planar FDSOI & trigate

technologies INAC, STM, LETI

ANR/P2N2013 NOODLES 13/01/2016 20

Comparison with experimental data

• Trends in good agreement in good agreement with experimental data

Note that NEGF misses the contribution from the metal/semiconductor contact, estimated

to be ~20 .m.

• Perspectives :

• Contact resistances at high fields (saturation).

• Contact optimization (in progress).

L. Bourdet et al., submitted to JAP

INAC, STM,

LETI

ANR/P2N2013 NOODLES 13/01/2016 21

Impact of the access regions

• On the ‘apparent’ mobility degradation in Bulk and

UTBB-FDSOI devices.

• On the Drain Current in MOSFET Transistors: the role

of the saturation.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.610

-10

10-9

10-8

10-7

10-6

10-5

10-4

NO

RM

ALI

ZE

D C

UR

RE

NT

(A

)

GATE VOLTAGE (V)

Long device

Short device

What drive current reduction?

• Mobility reduction

• Velocity saturation effects

• Quantum resistance

• Pinch Off

• LDD Region

Sat

Lin

STM

ANR/P2N2013 NOODLES 13/01/2016 22

Total Resistance: Derived Model

• Large access resistance below the spacer. TCAD simulation has been

used to show these regions in terms of square resistance. The LDD

resistance is a root cause of the ‘apparent’ mobility degradation

• The saturation velocity acts like an external resistance. The model is

justified from P&S derivation.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.80

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2x 10

4

Ron

.

m

L ( m.)

VD 0.05V: Mean Error = 4.8 %

VD 0.24V: Mean Error = 3 %




VD 1V: Mean Error = 1.4 %

0 0.05 0.1

500

1000

1500

2000


VD 0.24V: Mean Error = 3 %



(Linear)

(Saturated Pinchoff)

0*

00

22)(

1

)(

1R

Cv

V

VVCVVCLR

OX

D

THGOXTHGOX

on

0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

0

500

1000

1500

2000

VG - VTH (V)

CH

AN

NE

L R

ES

IST

AN

CE

(L=

0.0

204

m)

[ .

m

]

VD 0.24V:

linext = 0.022

=0.0062

VD 0.43 V:

satext = 0.016

ext

=0.46

VD 0.62 V:

satext = 0.023

ext

=0.18

VD 0.81 V:

satext = 0.023

ext

=0.17

VD 1 V:

satext = 0.023

ext

=0.17

VD 0.05V:

linext = 0.024

=0.0047

0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

0

500

1000

1500

2000

2500

VG - VTH (V)

EX

TR

AC

TE

D R

ES

IST

AN

CE

[

.

m]

VD 0.05V: = 30

R0 =53

VD 0.24V: = 59

R0 =37

VD 0.43V: = 76

R0 =83

VD 0.62V: = 1.3e+002

R0 =52

VD 0.81V: = 1.7e+002

R0 =72

VD 1V: = 2.1e+002

R0 =80

THG

D

OX

D

THGTHGOX

D

THGTHGOX

Don

VV

VR

Cv

V

VVVVC

V

VVVVC

VLR

0*

00

2)(

2

)(

2

)()(

2

Experimental 14FD GO1

STM

ANR/P2N2013 NOODLES 13/01/2016 23

Carrier injection engineering in NW via dopant

and shape monitoring of the access regions

• Constriction: Subband mismatch

Tunnel barrier.

• Injection: Governed by impurity

level, not Fermi level.

• Smaller AR cross section

Lower impurity level (Dielectric

Confinement) Better injection.

IM2NP

S. Berrada, et al., Appl. Phys. Lett. 107, 153508 (2015)

ANR/P2N2013 NOODLES 13/01/2016 24

Exploratory study: time-dependent regimes

Initial perspective

• Develop efficient strategies in terms of methodology and numerical

algorithms to deal with time-dependent problems in electronics

Results

Formal derivation of time-dependent energy and heat currents within the

self-consistent Born approximation

Algorithmic scheme of the wave function approach proposed by Gaury and

co-authors* including the electron-boson interaction (I-WF) self-

consistently

Perspectives

Numerical implementation of the I-WF approach for optoelectronic

applications, e.g. optoelectrical pump-probe experiments

Katawoura BELTAKO, PhD started in October 2015 at the IM2NP

Time-dependent quantum thermodynamics

IM2NP

ANR/P2N2013 NOODLES 13/01/2016 25


• Influence of the high-k gate oxide on the dielectric

screening

• Incorporation of the Schottky contact in the access

regions

• Self-heating as a function of the shape and doping of the

access regions

Realistic description of the injection in nanodevices:

reduction of the contact resistance at the nanometer

scale.

ANR/P2N2013 NOODLES 13/01/2016 26

Task 4

Alternative channel

materials for LOP

applications

ANR/P2N2013 NOODLES 13/01/2016 27

Influence of uniaxial strain in Si and Ge p-type

DG MODFETs

• Hamiltonian: 6 band k.p model +

Bir-Pikus for the strain

• Comparison between strained Si

and Ge devices at LG=14 and 7 nm

Ge uni-axial compression: the best solution in long devices

The small effective mass of Ge becomes a drawback in short devices

< 100 >-tensile provides the best electrical properties for LG=7 nm

IM2NP

M. Moussavou, et al., J. Appl. Phys. 118, 114503 (2015)

ANR/P2N2013 NOODLES 13/01/2016 28

Broken-gap HJ tunnel-FETs to increase ION

• Study of alternative design option to increase the Ion of

broken-gap HJ TFETs without degrading the sub-VT

swing

M. Pala et al., IEEE-JEDS (2015)

IMEP-LAHC

ANR/P2N2013 NOODLES 13/01/2016 29


• Systematic comparison between Si and III-V devices

• Assessment of the impact of variability in III-V and Ge

devices

ANR/P2N2013 NOODLES 13/01/2016 30

Task 5

Analytical equations for

compact modeling

ANR/P2N2013 NOODLES 13/01/2016 31

Device compact modelling for roadmap

prediction : III-V devices

Vt shift induced by quantum

effect in III-V NW for variability

[Hiblot, Rafhay, Boeuf,

Ghibaudo, SSE oct 2014]

Impact of quantum effect on

heavily doped III-V bulk device


Ghibaudo, ESSDERC sept 2014]

Improvement of boundary

condition for SCEs models


Ghibaudo, TED 2015]

All developed models implemented in Mastar platform

Available now: - Improved and comprehensive SCEs models (all architectures, impact of spacers and

underlap)

- Quantum leakage : SDT on parabolic potential, simple BTBT

- 1st basic thermal effects

- Comprehensive parasitic capacitance model (main source of performance degradation)

IMEP-LAHC, STM

ANR/P2N2013 NOODLES 13/01/2016 32

A roadmap for III-V available in MASTAR

• To obtain a 5%/year reduction

of the delay, III-V should be

introduced in 2017

• Main problem: increased

variability of Vth due to

stronger quantum effects

IMEP-LAHC, STM

ANR/P2N2013 NOODLES 13/01/2016 33

OFF-state physics of MOSFETs and TFETs

• Semi-analytical model based on the “natural length” concept

• DIBL of MOSFETs and TFETs scales similarly

• SS is below 60mV/dec only for well-tempered TFETs : LG>6 λ

D. Esseni et al., IEEE-TED (2015)

IMEP-LAHC

ANR/P2N2013 NOODLES 13/01/2016 34


• Inclusion data on resistances and capacitances from

other tasks

• Use of semi-analytical models to evaluate the variability

of different devices for various geometrical lengths and

VDD

• Simulation of simple circuits (2 transistors) via NEGF

methods

ANR/P2N2013 NOODLES 13/01/2016 35

Task 6

Comparison with

characterization data

ANR/P2N2013 NOODLES 13/01/2016 36

Vbg = 0 V SiO2 (BOX)

Silicon film

SiO2 interfacial layer

HfO2 (« High-k »)

Metal gate

Modeling FDSOI technologies

• Fully-Depleted Silicon on Insulator devices (FDSOI28/14) from STMicro, with back gate

biasing.

tIL

INAC, LETI,

STM

ANR/P2N2013 NOODLES 13/01/2016 37

• Consistent description of electrons and holes with a single set of structural

parameters (SR, traps…)

• Extrapolation down to 10 nm planar FDSOI technologies and FinFET devices.

Modelling FDSOI technologies

JAP (2014) ; IEEE TED (2014) ; APL (2015)

INAC, LETI,

STM

ANR/P2N2013 NOODLES 13/01/2016 38


• Predictive simulations for the design of new devices with

the aim of

– Reduction of contact resistances and parasitic

capacitances.

– Optimal use of back-gating for multi-VT (threshold

voltage) architectures, and advantage of FDSOI

technology.

– Minimization of short-channel effects.

ANR/P2N2013 NOODLES 13/01/2016 39

Perspectives of the second part of the project

Each task evolves as planned

The last part of the project will be mainly devoted to

complete the planned work of the various tasks and to

identify the optimal device/material configuration at different

geometrical lengths and supply voltages

More informations: http://noodles.minatec.grenoble-inp.fr

ANR/P2N2013 NOODLES 13/01/2016 40

Nombre de publications dans des revues

internationales à comité de lecture :

Multipartenaires : 8

Monopartenaires : 5

Nombre de publications dans des actes de conférences

internationales:

Multipartenaires : 6

Monopartenaires : 14

Indicateurs du project: publications au 01/09/15

ANR/P2N2013 NOODLES 13/01/2016 41

Nombre d’embauches dans le cadre du projet :

Devenir des non-CDI à la fin de leur contrat :

Nom Prénom Sigle du

partenaire

Contrat

Type de contrat * Date début Durée (mois)

Logoteta Demetrio IMEP-LAHC Post-Doctorat 13/03/2014 24

Zaoui Hayat IEMN Thèse 01/09/2014 36

Zampa Sonia IEMN Ingénieur 01/09/2015 4

Berrada Salim IM2NP Post-Doctorat 01/05/2014 15

Nom Prénom Type de

contrat *

Société ou organisme Date

recrutement Nom Région

Berrada Salim CDI INSA Euromed

de Fès Maroc 01/09/2015

* Type de contrat = CDI, Thèse, Post-Doctorat, CDD Chercheur, CDD Ingénieur, CDD technicien, stage, autre.

Indicateurs du projet: embauches

ANR/P2N2013 NOODLES 13/01/2016 42

THANK YOU FOR YOUR

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