Hiroshi Iwai

Frontier Research Center

Tokyo Institute of Technology

Future of Nano CMOS Technology

May 26, 2014,

IEEE EDS MQ at KTH, Kista, Stockholm, Sweden

1

Back ground for nano-electronics

2

3

(1970) 10 μm 8 μm 6 μm 4 μm 3 μm 2 μm 1.2 μm

0.8 μm 0.5 μm 0.35 μm 0.25 μm 180 nm 130 nm

90 nm 65 nm 45 nm 32 nm (28 nm ) 22 nm(2012)

Feature Size / Technology Node

From 1970 to 2013 (Last year)

18 generations

Line width: 1/450

Area: 1/200,000

43 years 1 generation

2.5 years

Line width: 1/1.43 = 0.70

Area: 1/2 = 0.5

14 nm (2014)

LDiffusive transport

LBallistic transport

~L

Quasi-Ballistic transport

L ：Mean free pathsource drain

Mobility

Theory

Real nanoscale

MOSFETs

Back scattering

from drain

Ballistic transport will never

happen for MOSFET because

of back scattering at drain

With decreasing channel length,

Drain current increase continue.

一次元バリスティック伝導

Also, 1D quantum conduction, or ballistic conduction will not happen.

Ballistic conduction will not happen

even decreasing channel lengh.

(1D quantum conduction: 77.8mS regardless of the length and material).4

5

Then, now!.

Noticed that the technology is difficult.

Development of EUV (Extreme Ultra Violet)

lithography delayed significantly.

https://www.google.co.jp/search?q=euv&tbm=isch&tbo=u&source=univ&sa=X&ei=ikY8U5asC8HXyAGok4DwCA&ved=0CDgQsAQ&biw=1745&bih=828#facrc=_&imgrc=KmzxirNdZ0cBM

%253A%3B6JNTCrv867Tq0M%3Bhttp%253A%252F%252Ftechon.nikkeibp.co.jp%252Farticle%252FNEWS%252F20061017%252F122347%252FEUV.jpg%3Bhttp%253A%252F%252

Ftechon.nikkeibp.co.jp%252Farticle%252FNEWS%252F20061017%252F122347%252F%253FSS%253Dimgview_scr%2526FD%253D-672378983%3B750%3B562

6

Noticed that the technology is difficult.

- Reduction of the thickness of High-k gate oxide

becomes very difficult.

In addition with the significant delay in EUV

(Extreme Ultra Violet) lithography delayed

significantly,

- Decreasing supply voltage becomes difficult

because of subtreshold leakage and

variability of thereshold voltage.

Now

7

Technology development delayed.

Number of the semiconductor companies which can develop

state of the art technology decreasing.

In the past, technologies come with the purchase of

equipment's

But now, every companies are facing threat of dropping off,

unless they concentrated on the development of

technologies.

Shrink rate of gate length will become from 07 to 0.8 or 0.85.

Thus, technology development is becoming much

important.

8

Near future smart-society has to treat huge

data.

Demand to high-performance and low power

CMOS become much more stronger.

9

Semiconductor Device Market will

grow 5 times in 12 years, even

though, it is very matured market!!

Gartner: By K. Kim, CSTIC 2012

300B USD

2011

1,500B USD

2025

What is the problem for downsizing?

Question

10

The problem for downsizing

Ioff increase: Transistor cannot be turned-off.

Ioff (Off-leakage current) between S and D

11

1. Punch-through between S and D

2. Direct-tunneling between S and D

3. Subthreshold current between S and D

S and D distance small

Ion & Ioff increase

12

1. Punch-through between S and D

Gate oxide

Gate metal

Source Drain

1V0V0V

Substrate 0V Depletion

Region (DL)

by Drain Bias

1V

0V 0V

tox and Vdd have to be decreased for better channel

potential control IOFF Suppression

0V < Vdep＜1V

0V

0V < Vdep＜1V

Channel

0V

0V

0V0V

0.5V

Large IOFF

Region governed

By drain biasRegion governed

by gate bias

DL touch with S

Region (DL)

Large IOFF

No tox. Vdd

thinning

Vdd

Vdd

13

Problem for downsizing

(Electron current)

14

1. Punch-through between S and D

There are 3 solutions to suppress the depletion layer

A. Decrease supply voltage Very difficult

B. Decrease tox to enhance the channel potential controllability by gate bias

as explained later

C. Gate/channel configuration change to enhance the channel potential controllability by gate bias

Fin-FET, ET-SOI, etc.

A. Toriumi (Tokyo Univ), IEDM 2006, Short Course

t ox(

(

15

B.Decrease tox

16

C. Configuration change for channel and gate structures for better control of channel potential.

Fin-FET, ET-SOI, etc.

1V0V

0V

S

0V

0V ＜V＜1V

1V0V

0V

0V

0VS D

G

G

G

Extremely Thin (or Fully-Depleted) SOI

Planar ET (or FD) SOI17

Si

SiO2

Extremely

thin Si

Drain bias

induced

depletion

- Make Si layer thin

- Control channel potential also from the bottom

1V0V

0V

S

0V

0V ＜V＜1V

1V0V

0V

0V

0VS D

G

G

G

Surrounding gate structure (Multiple gates)

PlanarMulti gate

18

Si fin or

nanowire

Drain bias

induced

depletion

- Make Si layer thin

- Control channel potential also by multiple gates

not only from top & bottom but maybe also

from side

Fin Tri-gate

(Variation)

W-gate All-around

G G G

G

G

Multi-gate structures

19

G

Tri-gate

New structures!

Our work at TIT: W-gate Si NanowireS. Sato et al., pp.361, ESSDERC2010 (Tokyo Tech.)

19 nm

12 nm

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

-1.5 -1.0 -0.5 0.0 0.5 1.0

10-12

Gate Voltage (V)

pFET nFET

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

Dra

in C

urr

en

t (A

)

Vd=-50mV

Vd=-1V

Vd=50mV

Vd=1V

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

-1.5 -1.0 -0.5 0.0 0.5 1.0

10-12

Gate Voltage (V)

pFET nFET

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

Dra

in C

urr

en

t (A

)

Vd=-50mV

Vd=-1V

Vd=50mV

Vd=1V

0 0.5 1 1.5 2ION (mA/mm)

Lg=65nm

0 0.5 1 1.5 2ION (mA/mm)

Lg=65nm

Lg=65nm

Poly-Si

SiO2

SiNSiN

SiO2

NW

・Conventional CMOS process

・High drive current

(1.32 mA/mm @ IOFF=117 nA/mm)

・DIBL of 62mV/V and SS of 70mV/dec

for nFET20

21

2. Direct-tunneling between S and D

Wave function of electron penetrates the channel potential barriers by quantum mechanical physics, when the channel length is around 3 nm.

Tunnelingdistance

3 nm

Source DrainChannel

22

Ene

rgy o

r P

ote

ntia

l

for

Ele

ctr

on

Direct-tunnelcurrent

There is no solutions!

Downsizing limit is @ Lg = 3 nm.

Built-in potential

between Source

and Channel pn

junction < 0.7 V

When transistor is at off state

23

3. Subthreshold current between S and D

24

Vg

Id

Vth

(Threshold Voltage)

Vg=0V

Subthreshould

Leakage Current

Subtheshold leakage current of MOSFET

ONOFF

Ion

Subthreshold

region

25

Vg (V)1

0.3 V

0.5 V 1.0 V

Ion

Ioff

Id (A/mm)

10-7

10-5

10-11

10-9

Vd

Vth

0.15 V

0 0.5

Subthreshold leakage current

Electron Energy

Boltzmann statics

Exp (qV/kT)

Lg 1/2

Vd, Vg 1/2

Vth 1/2

Ioff 103 in this example

However

Because of

log-linear dependence

26

Vg

Id

Vth

(Threshold Voltage)

Vg=0V

Subthreshould

Leakage Current

Subtheshold leakage current of MOSFET

Subthreshold Current

Is OK at Single Tr. level

But not OK

For Billions of Trs.

ONOFF

Ion

Subthreshold

region

27

3. Subthreshold current between S and D

Solution: however very difficult

Keep Vth as high as possible

- Do not decrease supply voltage, Vd

- Suppress variability in Vth

However, punchthough enhanced

Thus, subthreshold current will limit the downsizing, especially for mobile devices

28Subthreshold Leakage (A/mm)

Op

era

tio

n F

req

ue

nc

y (

a.u

.)

e)

100

10

1

Source: 2007 ITRS Winter Public Conf.

The limit is deferent depending on application

How far can we go for production?

10mm 8mm 6mm 4mm 3mm 2mm 1.2mm 0.8mm 0.5mm

0.35mm 0.25mm 180nm 130nm 90nm 65nm 45nm 32nm

(28nm) 22nm 14nm 11.5 nm 8nm 5.5nm? 4nm? 2.9 nm?

Past 0.7 times per 2.5 years

Now Future

・At least 4,5 generations to 8 ~ 5 nm

29

Intermediate

node

Direct-tunnelSubthreshold

punchthrough

Limit depending

on applications

Fundamental

limit

However, careful about the name of technology!

22 nm Technology by Intel

Lg (Gate length) = 30 nm (HP), 34 nm (MP), 34 nm or larger (SP)

IEDM 2012, VLSI 2013

10 nm Technology by Leti (FD-SOI)

Lg (Gate length) = 25 nm Euro SOI 2014

Recently,

Gate length (Lg) is much larger than the Technology name

14 nm Technology by Global

Lg (Gate length) = 15 nm

2015 2017 2019 20252021 2023 20272013

10 7 5 1.83.5 2.5 1.314

32 25.3 20 1015.9 12.6 840

19 16 13.3 7.711.1 9.3 6.423

16.8 14.0 11.7 6.79.7 8.1 5.620.2(10) (8) (6) (5)(13)

0.73 0.67 0.61 0.470.56 0.51 0.430.80(0.60) (0.55) (0.50) (0.50)(0.60)

0.83 0.80 0.77 0.680.74 0.71 0.650.86(0.80) (0.70) (0.70) (0.65)(0.90)

6.1 5.1 4.3 2.53.6 3.0 2.07.4(6.0) (4.5) (3.8) (3.2)(6.0)

Year

Lg (nm)

Metal half pitch (nm)

(Lg for ITRS 2007)

Commercial name (nm)

Lg for low stand by power (nm)

Vdd (V) (Vdd (V) for ITRS 2007)

EOT (nm) (EOT (nm) for ITRS 2007)

TSi (nm) (TSi (nm) for ITRS 2007)

(4.5 in 2022)

(3.0 in 2022)

(0.50 in 2022)

(0.65 in 2022)

ITRS 2013 (Just published in April 2014)

The rate for the shrinkage for the gate length and

line pitch will be larger than 0.7 in near future,

because of the subthreshold leakage, and also

because of the delay in EUV lithography.

As a result, we will have more technology

generations until reaching the downsizing limit,

and the time to reach the limit will be delayed.

How far can we go for production?

33

Thus, we may go down to “1.5 nm”

technology node by choosing

whatever gate length we want for the

application.

More Moore to More More Moore

65nm 45nm 32nm

Technology node

M. Bohr, pp.1, IEDM2011 (Intel)

P. Packan, pp.659, IEDM2009 (Intel)

C. Auth et al., pp.131, VLSI2012 (Intel)

T. B. Hook, pp.115, IEDM2011 (IBM)

S. Bangsaruntip et al., pp.297, IEDM2009 (IBM)

Lg 35nm Lg 30nm

(Fin,Tri, Nanowire)

22nm15nm, 11nm, 8nm, 5nm, 3nm

Alternative (III-V/Ge)

Channel FinFET

Emerging

Devices

Tri-Gate

Now Future

Si channel

Si

Others

(ETSOI)Planar

Si is still main stream for future !! ET: Extremely Thin28nm

High-k gate dielectrics

Continued research

and development

SiO2 IL (Interfacial Layer)

is used at Si interface to

realize good mobility

Technology for direct contact of

high-k and Si is necessary

Remote SiO2-IL

scavenging

HfO2 (IBM)

EOT=0.52 nm

Si

La-silicate

MG

Direct contact with La-silicate (Tokyo.Tech)

T. Ando, et al., p.423, IEDM2009, (IBM)

T. Kawanago, et al., T-ED, vol. 59, no.

2, p. 269, 2012 (Tokyo Tech.)

K. Mistry, et al., p.247, IEDM 2007, (Intel)

TiN

HfO2

Si

SiO2

EOT=0.9nm

HfO2/SiO2

(IBM)

T.C. Chen, et al., p.8, VLSI 2009, (IBM)

Hf-based oxides

45nm

EOT:1nm

32nm

EOT:0.95nm

22nm

EOT:0.9nm15nm, 11nm, 8nm, 5nm, 3nm,

K. Kakushima, et al., p.8, IWDTF 2008,

(Tokyo Tech.)

EOT=0.37nm EOT=0.40nm EOT=0.48nm

0.48 → 0.37nm Increase of Id at 30%

35

High-k is very important, however

very difficult.

36

Thickness (EOT) decreased only

0.05 nm (or 0.5 Å, or 1 atom

layer) for every generation.

How far can we go for production?

37

Now, Ion/Ioff ratio is typically 106.

However, it degrades significantly

with decrease in Vsupply.

Rather than Ioff value, Ion/Ioff ratio

is important.

[a] C. Auth et al., pp.131, VLSI2012 (Intel).[b] K. Mistry et al., pp.247, IEDM2007 (Intel).[c] H.-J. Cho et al., pp.350, IEDM2011 (Samsung).[d] S. Saitoh et al., pp.11, VLSI2012 (Toshiba).[e] S. Bangsaruntip et al., pp.297, IEDM2009 (IBM).

[f] T. Yamashita et al., pp.14, VLSI2011 (IBM).[g] A. Khakifirooz et al., pp.117, VLSI2012 (IBM).

ION and IOFF benchmark

[h] G. Bidal et al., pp.240, VLSI2009 (STMicroelectronics).[i] S. Sato et al., pp.361, ESSDERC2010 (Tokyo Tech.)[j] K. Cheng et al., pp.419, IEDM2012 (IBM)

1

10

100

1000

10000

0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2

ION [mA/mm]

I OF

F[n

A/m

m]

NMOS

Intel [a]

Bulk 32nm

VDD=0.8V

Intel [a]

Tri-Gate 22nm

VDD=0.8V

Intel [b]

Bulk 45nm

VDD=1V

Toshiba [d]

Tri-Gate NW

VDD=1V

Samsung [c]

Bulk 20nm

VDD=0.9V

IBM [5]

GAA NW

VDD=1V

IBM [g]

FinFET 25nm

VDD=1V

IBM [g]

ETSOI

VDD=0.9V

IBM [g]

ETSOI

VDD=1V

STMicro. [h]

GAA NW

VDD=0.9V

STMicro. [h]

GAA NW

VDD=1.1V

Tokyo Tech. [i]

W-gate NW

VDD=1VIBM [j]

ETSOI

VDD=0.9V

Ieff

1

10

100

1000

10000

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6

ION [mA/mm]

I OF

F[n

A/m

m]

PMOS

Intel [a]

Bulk 32nm

VDD=0.8V

Intel [a]

Tri-Gate 22nm

VDD=0.8V

Intel [b]

Bulk 45nm

VDD=1V

IBM [g]

ETSOI

VDD=1VSamsung [c]

Bulk 20nm

VDD=0.9V

IBM [e]

GAA NW

VDD=1V

IBM [f]

FinFET 25nm

VDD=1V

IBM [g]

ETSOI

VDD=0.9V

STMicro. [h]

GAA NW

VDD=1.1V

IBM [j]

ETSOI

VDD=0.9V

Ieff

Nanowire/Tri gate MOSFETs have

advantage not only suppressing Ioff,

but also for increasing Ion over planer

MOSFETs

39

1. Because of higher mobility due to

lower vertical electric field

2. Because of higher carrier density at

the round corner

40

0.E+00

1.E+19

2.E+19

3.E+19

4.E+19

5.E+19

6.E+19

0 2 4 6 8Distance from SiNW Surface (nm)

6

5

4

3

2

1

0

角の部分

平らな部分

電子濃度(x1019cm-3)Electron Density

Edge portion

Flat portion

41

3. Now Problems for downsizing!

42

We have to decrease Si layer

thickness to better control of

channel potential by gate bias

when we decrease the gate length.

Significant decrease in conduction

or Ion.

2015 2017 2019 20252021 2023 20272013

10 7 5 1.83.5 2.5 1.314

Year

Commercial name (nm)

6.1 5.1 4.3 2.53.6 3.0 2.07.4(6.0) (4.5) (3.8) (3.2)(6.0)

TSi (nm) (TSi (nm) for ITRS 2007) (3.0 in 2022)

0.73 0.67 0.61 0.470.56 0.51 0.430.80(0.60) (0.55) (0.50) (0.50)(0.60)

EOT (nm) (EOT (nm) for ITRS 2007) (0.50 in 2022)

ITRS 2013

Short-channel effectT. Skotnicki, IEDM 2009 Short Course (STMicroelectronics)

44

45

Mobility degradation for small

diameter nanowire FETs, because

channel carriers become too

close to all surrounding nanowire

surface, and scattered strongly.

S. Bangsaruntip et al., pp.297, IEDM2009 (IBM),

K. Tachi et al., pp.313, IEDM2009 (CEA-LETI)

Decreasing the diameter of NW

Problems in Multi-gate

Improved

short-channel control

Severe mobility

degradation

Significant m degradation

at diameter < 10 nm Need to decrease

diameter for SCH

46

K. Uchida et al., pp.47, IEDM2002 (Toshiba)

Problems in SOI

Mobility is also decreased with

decreasing the Si thickness of SOI

transistor similar to the NW transistor.47

When wire diameter becomes less than 10 nm, sudden drop of Id

Problem for nanowire

Id

Diameter

10 nm

2. Electron density decrease

If diameter cannot be scaled, SCE cannot be suppressed.

Then, again aggressive EOT scaling of high-k is necessary. 48

< 10 nm

1. Mobility degradation

Extremely small distance between the

electron and all around Si surface.

Strong scattering of electrons by interaction

with all around Si surface.

Decrease of DOS in extremely narrow wire.

49

Carrier density degradation for

small diameter nanowire FET,

because of the decrease in

density of states.

Number of quantum channels

Energy band of Bulk Si

Eg

By Prof. Shiraishi of Tsukuba univ.

Energy band of 3 x 3 Si wire

4 channels can be used

Eg

50

51By Profs. Oshiyama and Iwata, U. of Tokyo

Diameter dependence1 nm 2 nm 3 nm 4 nm 6 nm

K. Kim, pp.1, IEDM2010 (Samsung)

1.2

1.1

1

0.9

0.8

0.7

0.6

0.5

EO

T [

nm

]

202020152010

Year

12

10

8

6

4

2

0

Bo

dy T

hic

kn

ess [n

m]

Multi-

GatePlanar

ITRS2011

Fin width

EOT Scaling Trends

Smaller wire/fin width is necessary for SCE suppression

But mobility and ION severely degrade with wire/fin width reduction

Therefore even in multi-gate structures, EOT scaling should be

accelerated to provide SCE immunity 52

High-k

beyond 0.5 nm

53

New Materials!

To use high-k dielectrics

Thin SiO2

Thick high-k

dielectrics

Almost the same

electric characteristics

However, very difficult and big challenge!

K: Dielectric Constant

5 times thicker

Small

leakage

Current

K=4K=20

Solution

SiO2 High-k

54

R. Hauser, IEDM Short Course, 1999Hubbard and Schlom, J Mater Res 11 2757 (1996)

●

● Gas or liquid

at 1000 K

●H

○Radio activeHe

● ● ● ● ● ●Li BeB C N O F Ne

① ● ● ● ●Na

Mg Al Si P S Cl Ar

② ① ① ① ① ① ① ① ① ① ① ● ● ● ●K Ca Sc Ti V Cr Mn Fc Co Ni Cu Zn Ga Ge As Se Br Kr

● ① ① ① ① ① ● ① ① ① ① ① ● ●Rh Sr Y Zr Nb Mo Tc Ru Rb Pd Ag Cd In Sn Sb Te I Xe● ③ ① ① ① ① ① ● ● ● ● ① ① ○ ○ ○Cs Ba

★ HfTa W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

○ ○ ○ ○ ○ ○ ○ ○Fr Ra ☆ Rf Ha Sg Ns Hs Mt

○La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yｂ Lu○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

★

☆

Candidates

● ●Na Al Si P S Cl Ar

② ① ① ① ① ① ① ① ① ① ● ● ● ●K Sc Ti V Cr Mn Fc Co Ni Cu Zn Ga Ge As Se Br Kr

● ① ① ① ① ① ● ① ①

○ ○ ○ ○ ○ ○Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

★

☆

②

③

Unstable at Si interfaceSi + MOX M + SiO2①

Si + MOX MSiX + SiO2

Si + MOX M + MSiXOY

Choice of High-k elements for oxide

HfO2 based dielectrics

are selected as the

first generation

materials, because of

their merit in

1) band-offset,

2) dielectric constant

3) thermal stability

La2O3 based

dielectrics are

thought to be the next

generation materials,

which may not need a

thicker interfacial

layer

55

0 10 20 30 40 50

Dielectric Constant

4

2

0

-2

-4

-6

SiO2

Ba

nd

Dis

co

nti

nu

ity [

eV

]Si

XPS measurement by Prof. T. Hattori, INFOS 2003

Conduction band offset vs. Dielectric Constant

Band offset

Oxide

Leakage Current by Tunneling

56

SiO2-ILHfSix (k~4)

VO

IO

IO

VO

VO

IO

IOVO

HfO2

Si substrateSiO2-IL

(k~4)

LaSix

VO

IOVO

IO

VO

IOLa2O3

silicateLa-rich Si-rich

Si substrate

High PO2Low PO2 High PO2Low PO2

HfO2 case La2O3 case

Direct contact can be achieved with La2O3 by forming silicate at interface

Control of oxygen partial pressure is the key for processing.

Our approach

K. Kakushima, et al., VLSI2010, p.69

Direct high-k/Si by silicate reaction

PO2: Partial pressure of O2 during

high temperature annealing

1837184018431846

Binding energy (eV)

Inte

ns

ity

(a

.u)

Si sub.

Hf SilicateSiO2

500 oC

1837184018431846

Binding energy (eV)

Inte

ns

ity

(a

.u)

Si sub.

Hf SilicateSiO2

500 oC

SiOx-IL

HfO2

W

1 nm

k=4

k=16

SiOx-IL growth at HfO2/Si Interface

HfO2 + Si + O2 → HfO2 + Si + 2O*→HfO2+SiO2

Phase separator

SiOx-IL is formed after annealing

Oxygen control is required for optimizing the reaction

Oxygen supplied from W gate electrode

XPS Si1s spectrum

D.J.Lichtenwalner, Tans. ECS 11, 319

TEM image500 oC 30min

H. Shimizu, JJAP, 44, pp. 6131

La-Silicate Reaction at La2O3/Si

La2O3

La-silicate

W

500 oC, 30 min

1 nm

k=8~14

k=23

1837184018431846

Binding energy (eV)

Inte

nsit

y (

a.u

)

as depo.

300 oC

La-silicate

Si sub.

500 oC

1837184018431846

Binding energy (eV)

Inte

nsit

y (

a.u

)

as depo.

300 oC

La-silicate

Si sub.

500 oC

La2O3 + Si + nO2

→ La2SiO5, La2Si2O7,

La9.33Si6O26, La10(SiO4)6O3, etc.

La2O3 can achieve direct contact of high-k/Si

XPS Si1s spectraTEM image

Direct contact high-k/Si is possible

60

① silicate-reaction-formed

fresh interface

metal

Si sub.

metal

Si sub.

La2O3 La-silicateSi Si

Fresh interface with

silicate reaction

J. S. Jur, et al., Appl. Phys. Lett.,

Vol. 87, No. 10, (2007) p. 102908

② stress relaxation at interface

by glass type structure of La

silicate.

La atom

La-O-Si bonding

Si sub.

SiO4tetrahedron network

FGA800oC is necessary to

reduce the interfacial stress

S. D. Kosowsky, et al., Appl. Phys. Lett.,

Vol. 70, No. 23, (1997) pp. 3119

Physical mechanisms for small Dit

61

2

1.5

1

0.5

0

Capacitance [m

F/c

m2]

-1 -0.5 0 0.5 1

Gate Voltage [V]

10kHz 100kHz 1MHz

20 x 20mm2

1.5

1

0.5

0

Ca

pa

cita

nce

[m

F/c

m2]

-1.5 -1 -0.5 0 0.5

Gate Voltage [V]

20 x 20mm2

10kHz 100kHz 1MHz

2

1.5

1

0.5

0

Ca

pa

cita

nce

[m

F/c

m2]

-1.5 -1 -0.5 0 0.5

Gate Voltage [V]

20 x 20mm2

10kHz 100kHz 1MHz

FGA500oC 30min FGA700oC 30min FGA800oC 30min

A fairly nice La-silicate/Si interface can be obtained

with high temperature annealing. (800oC)

However, high-temperature anneal is necessary

for the good interfacial property

5m

Robot

Flash Lamp

ALD

RTAEntrance

Sputter

for MG

EB Deposition for HK5m

Cluster tool for HKMG Stack

62

Cluster Chambers for HKMG Gate Stack

Flash Lamp

Anneal

EB Deposition: HK

Sputter: MG

ALD: HK

Robot

RTA

Entrance

63

substrate

①La gas

feed

②Ar purge ③H2O

feed④Ar purge

La

ligand HO

substrate substrate substrate

1 cycle

L a

C 3H 7

3

L a

C 3H 7

3

L a

C 3H 7

3

CLaN

NH

C3H7

C3H7

La(iPrCp)3 La(FAMD)3

Precursor

(ligand)

ALD is indispensable from the manufacturing viewpoint

- precise control of film thickness and good uniformity

K. Ozawa, et al., (Tokyo Tech. and AIST) Ext. Abstr.

the 16th Workshop on Gate Stack Technology and Physics., 2011, p.107.

64

ALD of La2O3

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

600 700 800 900 1000As depo

～ ～

Annealing temperature (oC)

EO

T (

nm

)

Annealed for 2 s

La2O3(3.5 nm)

W(60 nm)

TiN/W(12 nm)

TiN/W(6 nm)

TiN(45nm)/W(6nm)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

-1 -0.5 0 0.5

Vg (V)

Cg

(u

F/c

m2)

Experiment

Cvc fittingTheory

EOT=0.55nm

TaN/(45nm)/W(3nm)

900oC, 30min

EOT=0.55nm

65

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.5 0.55 0.6 0.65 0.7

Fla

t-ba

nd

vo

lta

ge

(V)

EOT（nm)

TaN(45nm)/W(3nm)

900oC, 30min

Qfix=1×1011 cm-2

Fixed Charge density: 1×1011 cm-2

66

0 0.2 0.4 0.6 0.8 1.0

Drain Voltage (V)

0.2

0.4

0.6

0.8

1.0

Dra

in C

urr

en

t (m

A)

Vg= 0.4V

Vg= 0.6V

Vg= 0.8V

Vg= 1.0V

Vg= 0.2V

Vg= 0 V

L/W = 5/20mm

T = 300K

Nsub = 3×1016cm-3

0

20

40

60

80

100

120

140

0 0.5 1 1.5 2 2.5

EOT = 0.40nm

L/W = 5/20mm

T = 300K

Nsub = 3×1016cm-3

Eeff [MV/cm]

Ele

ctr

on

Mo

bilit

y [

cm

2/V

sec]

EOT=0.40nm

Our Work at TIT: High-k

67

Our result at TIT

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

0.3 0.4 0.5 0.6 0.7 0.8

ITRS requirement

Jg

at 1

V (

A/c

m2)

EOT (nm)

Benchmark of La-silicate dielectrics

T. Ando, et al., (IBM) IEDM 2009, p.423

0

50

100

150

200

250

300

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

EOT (nm)M

ob

ility

(cm

2/V

se

c)

at 1 MV/cm

Open square : Hf-based oxides

Solid circle: Our data

Our data: La-silicate gate oxide

La-silicate gate oxide

L.-Å. Ragnarsson, et al., (IMEC) Microelectron. Eng, vol. 88, no. 7, pp. 1317–1322, 2011.

68

Gate Leakage current Effective Mobility

Si-sub.

Metal

SiO2-IL

High-k

Small interfacial state

density at high-k/Si

Oxygen diffusion control for

prevention of EOT increase

and oxygen vacancy

formation in high-k

Thinning or removal of

SiO2-IL for small EOT

Flat metal/high-k

interface for better

mobility

O

Workfunction engineering for

Vth control

Interface dipole control

for Vth tuning

Suppression of

oxygen vacancy

formation

Control of interface reaction

and Si diffusion to high-k

Oxygen concentration control

for prevention of EOT increase

and oxygen vacancy

formation in high-k

Suppression of

metal diffusion

Endurance for high

temperature process

Remove contamination

introduced by CVD

Reliability: PBTI,

NBTI, TDDB

Suppression of gate

leakage current

Suppression of FLP

69

Issues in high-k/metal gate stack

70

Thank you very much

for your attention.

71

Appendix

72

What is Next Revolution for Device Technology?

1900: Electronics

73

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

74

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

When?: What?

75

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

?: Nano Electronics

76

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

?: Nano Electronics

Maybe Not a Revolution

But Great Innovention

77

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

When?: What?

78

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

When?: What?

? years

79

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

When?: What?

70 years

? years

80

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

When?: What?

70 years

70 years

81

What is Next Revolution for Device Technology?

1900: Electronics

1970: Micro Electronics

2040: Braintronics

70 years

70 years

82We do know system and algorithms are important!But do not know how it can be by us for use of bio?

Braintronics

83

Source: H. Iwai, IPFA 2006

Size

Saturation of Downsizing

Some time in 2020 -2030

New Materials, New Process, New Structure

Hybrid integration of different functional Chip Increase of SOC functionality

3D integration of memory cell3D integration of logic devices

Low cost for LSI processRevolution for CR, Equipment

Miniaturization of Interconnects on PCB(Printed Circuit Board)

Introduction of algorithmof biosystemBrain of insects, human

After 2040?

We do not know how?

Long term roadmap for development

Braintronics

84

Braintronics for 2040’s

It’s a task for you,

For young generations!