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Evolution of Si CMOS Technologies to Sub-10 nm Generation
10:10-10:40, June 4, 2012
Hiroshi Iwai, Tokyo Institute of Technology
Electron Devices Colloquium – Imec, Leuven, Belgium
1
First Computer Eniac: made of huge number of vacuum tubes 1946Big size, huge power, short life time filament
Today's pocket PCmade of semiconductor has much higher performance with extremely low power consumption
dreamed of replacing vacuum tube with solid‐state device
2
1960: First MOSFET by D. Kahng and M. Atalla
Top View
Al Gate
Source
Drain
Si
Si
Al
SiO2
Si
Si/SiO2 Interface is extraordinarily good
3
1970,71: 1st generation of LSIs
DRAM Intel 1103 MPU Intel 4004
4
2012Most recent SD Card
Most Recent SD Card
128GB (Bite) = 128G X 8bit = 1024Gbit= 1.024T(Tera)bit
1T = 1012 = 1Trillion
Brain Cell:10~100 BillionWorld Population:7 Billion
Stars in Galaxy:100 Billion
Most Recent SD Card
2.4cm X 3.2cm X 0.21cm
Volume:1. 6cm³ Weight:2g
Voltage:2.7 - 3.6V
Old Vacuum Tube:5cm X 5cm X 10cm, 100g,100W
128 GB = 1Tbit
What are volume, weight, power consumption for 1Tbit
Old Vacuum Tube:5cm X 5cm X 10cm
1Tbit = 10,000 X 10,000 X 10,000 bitVolume = (5cm X 10,000) X (5cm X 10,000)
X (10cm X 10,000)= 0.5km X 0.5km X 1km
500 m
1,000 m
1Tbit
Burji KhalifaDubai, UAE(Year 2010)
828 m
Indian TowerMumbai, India(Year 2016)
700 m
700 m
Pingan IntenationalFinance CenterShanghai, China(Year 2016)
Old Vacuum Tube:100W
1Tbit = 1012bitPower = 0.1kWX1012=50 TW
Nuclear Power Generator1MkW=1BW We need 50,000 Nuclear Power Plant for
just one 128 GB memory
In Japan we have only 54 Nuclear Power Generator
Last summer Tokyo Electric Power Company (TEPCO) can supply only 55BW.
We need 1000 TEPCO just one 128 GB memory
Imagine how many memories are used in the world!
So progress of integrated circuits is extremely important for power saving.
12
Near future smart-society has to treat huge data.
Demand to high-performance and low power CMOS become much more stronger.
13
MemoryMemory[19%][19%]
MicrocompMicrocomp..[21%][21%]
Logic ICLogic IC[27%][27%]
Analog ICAnalog IC[15%][15%]
OthersOthers[18%][18%]
MemoryMemory[13%][13%]
MicrocompMicrocomp..[14%][14%]
Logic ICLogic IC[30%][30%]
Analog ICAnalog IC[10%][10%]
Emerging areasEmerging areas[33%][33%]
313 billion dollar (US) in 2011
1,528 billion dollar (US) in 2025
(Gartnerの市場予測)
Semiconductor Device Market will grow 5 times in 12 years!!
By K. Kim, CSTIC 2012
1900 1950 1960 1970 2000
VacuumTube
Transistor IC LSI ULSI
10 cm cm mm 10 µm 100 nm
In 100 years, the size reduced by one million times.There have been many devices from stone age.We have never experienced such a tremendous reduction of devices in human history.
10-1m 10-2m 10-3m 10-5m 10-7m
Downsizing of the components has been the driving force for circuit evolution
14
Downsizing1. Reduce Capacitance
Reduce switching time of MOSFETsIncrease clock frequency
Increase circuit operation speed2. Increase number of Transistors
Parallel processingIncrease circuit operation speed
Thus, downsizing of Si devices is the most important and critical issue.15
Downsizing contribute to the performance increase in double ways
16
(1970) 10 µm 8 µm 6 µm 4 µm 3 µm 2µm 1.2 µm
0.8 µm 0.5 µm 0.35 µm 0.25 µm 180 nm 130 nm 90 nm
Averaged downsizing rate (in the past 42 years): ~ 0.7X every 3 years
Total reduction in 19 generations: Gate Length ~ 1/500, Area ~ 1/250,000
65 nm 45 nm 32 nm 22 nm (2012)
Feature Size/Technology Node
Gate oxide
Gate metal
Source Drain
1V 0V0V
Substrate 0V DepletionRegion (DL)
1V
0V 0V
tox and Vdd have to be decreased for betterchannel potential control IOFF Suppression
0V < Vdep<1V
0V
0V < Vdep<1VChannel
0V
0V
0V0V
0.5V
Large IOFF
Region governed By drain bias
Region governed by gate bias
tOX thinning
DL touch with SRegion (DL)
Large IOFF
No toxthinning
Vdd
Vdd
17
Tunnelingdistance
3 nm
What would be the limit of downsizing!
Source DrainChannel
19
Vg (V)1
0.3 V
0.5 V 1.0 V
Ion
Ioff
Id (A/µm)
10-7
10-5
10-11
10-9
Vd
Vth
0.15 V
0 0.5
Subthreshold leakage current will limit the downsizing
20
Subthreshold Leakage (A/µm)
Ope
ratio
n Fr
eque
ncy
(a.u
.)
e)
100
10
1
Source: 2007 ITRS Winter Public Conf.
The limit is deferent depending on application
The down scaling of MOSFETs is still possible for at least another 10 years!
1. Thinning of high-k gate oxide thicknessbeyond 0.5 nm
2. Metal(Silicide) S/D
4. Wire channel
4 important technological items for down scaling.
New structures
New materials
3. III-V/Ge channel
1. High-k beyond 0.5 nm
Si-sub.
Metal
SiO2-IL
High-kSmall 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
Issues in highIssues in high--k/metal gate stackk/metal gate stack
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 contaminationintroduced by CVD
Reliability: PBTI, NBTI, TDDB
Suppression of gate leakage current
Suppression of FLP
23
0 10 20 30 40 50Dielectric Constant
4
2
0
-2
-4
-6
SiO2
Ban
d D
isco
ntin
uity
[eV]
Si
XPS measurement by Prof. T. Hattori, INFOS 2003
Conduction band offset vs. Dielectric Constant
Band offset
Oxide
Leakage Current by Tunneling
24
R. Hauser, IEDM Short Course, 1999Hubbard and Schlom, J Mater Res 11 2757 (1996)
Gas or liquidat 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 PmSmEu Gd Tb Dy Ho Er TmYb 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 in1) band-offset, 2) dielectric constant3) thermal stability
La2O3 based dielectrics are thought to be the next generation materials, which may not need a thicker interfacial layer
25
Direct highDirect high--k/Si by silicate reactionk/Si by silicate reaction
SiO2-ILHfSix (k~4)
VO
IO
IOVO
VO
IOIO
VOHfO2
Si substrate SiO2-IL(k~4)
LaSix
VO
IOVO
IO
VO
IOLa2O3silicate
La-rich Si-rich
Si substrate
High PO2Low PO2 High PO2Low PO2
SiO2 IL formation
Si substrate
silicate formation
Si substrate
HfO2 case La2O3 case
Direct contact can be achieved with La2O3 by forming silicate at interfaceControl of oxygen partial pressusre is the key for processing.
Our approach
K. Kakushima, et al., VLSI2010, p.69
27
1837184018431846Binding energy (eV)
Inte
nsity
(a.u
)
Si sub.
Hf SilicateSiO2
500 oC
1837184018431846Binding energy (eV)
Inte
nsity
(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 annealingOxygen control is required for optimizing the reaction
Oxygen supplied from W gate electrode
XPS Si1s spectrum
D.J.Lichtenwalner, Tans. ECS 11, 319
TEM image 500 oC 30min
H. Shimizu, JJAP, 44, pp. 6131
28
La-Silicate Reaction at La2O3/Si
La2O3
La-silicate
W
500 oC, 30 min
1 nm
k=8~14
k=23
1837184018431846Binding energy (eV)
Inte
nsity
(a.u
)
as depo.
300 oC
La-silicate
Si sub.
500 oC
1837184018431846Binding energy (eV)
Inte
nsity
(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
29
PMOS
High‐k gate insulator MOSFETs for Intel: EOT=1nm
HfO2 based high‐k
30Year
Pow
er p
er M
OSF
ET (P
)
P∝L
g 3
(Scaling)
EOT Limit0.7~0.8 nm
EOT=0.5nm
TodayEOT=1.0nm
Now
45nm node
One order of Magnitude
Si
HfO2
Metal
SiO2/SiON
Si
High-k
Metal
Direct ContactOf high-k and Si
Si
MetalSiO2/SiON
0.5~0.7nm
Introduction of High-kStill SiO2 or SiONIs used at Si interface
For the past 45 yearsSiO2 and SiON
For gate insulator
EOT can be reduced further beyond 0.5 nm by using direct contact to SiBy choosing appropriate materials and processes.
31
Substrate
Moving Mask
SourceElectron Beam
Flux
Deposited thin film
準備室
絶縁膜堆積室フラッシュランプアニール室
金属膜堆積室
ロボット搬送室
ALD室
RTA室
Robot
EB Evaporation Flash Lamp Anneal
ALD
RTA
Sputter
EB Evaporation
Flash Lamp Anneal
ALDRTAEntrance
Entrance
Sputter
High-k/metal gate stackfilm deposition cluster tool
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
0 0.5 1 1.5 2 2.5 3
EOT ( nm )
Cur
rent
den
sity
( A
/cm
2 )Al2O3HfAlO(N)HfO2HfSiO(N)HfTaOLa2O3Nd2O3Pr2O3PrSiOPrTiOSiON/SiNSm2O3SrTiO3Ta2O5TiO2ZrO2(N)ZrSiOZrAlO(N)
Gate Leakage vs EOT, (Vg=|1|V)
La2O3
HfO2
32
33
0.0E+00
5.0E-04
1.0E-03
1.5E-03
2.0E-03
2.5E-03
3.0E-03
3.5E-03
0 0.2 0.4 0.6 0.8 1
Vg=0VVg=0.2VVg=0.4VVg=0.6VVg=0.8VVg=1.0VVg=1.2V
0 0.2 0.4 0.6 0.8 1
Vg=0VVg=0.2VVg=0.4VVg=0.6VVg=0.8VVg=1.0VVg=1.2V
0 0.2 0.4 0.6 0.8 1
Vg=0VVg=0.2VVg=0.4VVg=0.6VVg=0.8VVg=1.0VVg=1.2VI d
(V)
W/L = 50µm /2.5µm
Vd (V) Vd (V) Vd (V)
EOT=0.37nm
Vth=-0.04VVth=-0.05VVth=-0.06V
EOT=0.37nm EOT=0.40nm EOT=0.48nmW/L = 50µm /2.5µm W/L = 50µm /2.5µm
0.48 0.37nm Increase of Id at 30%
La2O3 at 300oC process make sub-0.4 nm EOT MOSFET
34
2
1.5
1
0.5
0
Cap
acita
nce
[µF/
cm2 ]
-1 -0.5 0 0.5 1Gate Voltage [V]
10kHz 100kHz 1MHz
20 x 20µm2 1.5
1
0.5
0
Cap
acita
nce
[µF/
cm2 ]
-1.5 -1 -0.5 0 0.5Gate Voltage [V]
20 x 20µm2
10kHz 100kHz 1MHz
2
1.5
1
0.5
0
Cap
acita
nce
[µF/
cm2 ]
-1.5 -1 -0.5 0 0.5Gate Voltage [V]
20 x 20µm2
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
35
① silicate-reaction-formedfresh 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 atomLa-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 DitPhysical mechanisms for small Dit
36
No interfacial layer can be confirmed with Si/TiN/W
MIPSW TiN/W
Kav ~ 8 Kav ~ 12 Kav ~ 16
Si 2nm2nm2nm
HK
MG
La2O3Si/TiN/W
300
250
200
150
100
50
0
Elec
tron
Mob
ility
[cm
2 /Vse
c]
10.90.80.70.60.5EOT [nm]
at 1MV/cmT = 300K
Open : Hf-based oxides
Benchmark of LaBenchmark of La--silicate dielectricssilicate dielectrics
Gate leakage is two orders of magnitude lower than that of ITRS.
Electron mobility is comparable to record mobility with Hf-based oxides.
10-2
10-1
100
101
102
103
104
J g a
t Vg
= 1V
[A/c
m2 ]
0.80.750.70.650.60.550.5EOT [nm]
A = 10 x 10µm2
ITRS requirements
MIPS Stacks
This work (MIPS Stacks)
T. Ando, et al., (IBM) IEDM 2009, p.423
T. Kawanago, et al., (Tokyo Tech.) T-ED, vol. 59, no. 2, p. 269, 2012
37
substrate
①La gas feed ②Ar purge ③H2O feed ④Ar purge
Laligand H
O
substrate substrate substrate
1 cycle
ALD of LaALD of La22OO33
La
C 3H7
3
L a
C 3H7
3
L a
C 3H7
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.
38
Why high mobility channel materials?Why high mobility channel materials?
S D
1) High injection Velocity of carriers
2) High mobility of carriers
Both 1) and 2) are important
Arming higher performance at lower supply voltage
Problems: Technologies and CostInterfacial properties at the gate insulator/semiconductor
Contact resistance at Source/Drain and semiconductor
Different semiconductors for n- and p- channel FETs
Integration on Si wafer
vinj
III-V (n-channel) or Ge (p-channel)
39
17
0.17
mHH: 0.44mLH: 0.016
850
0.014
77000
InSb
14.8
0.36
mHH: 0.57mLH: 0.35
500
0.023
40000
InAs
0.0820.067mt: 0.082ml: 1.467
mt: 0.19ml: 0.916
electron effectivemass (/m0)
2004001900430hole mob.(cm2/Vs)
5400920039001600electron mob.(cm2/Vs)
12.6121611.8permittivity
1.341.420.661.12band gap (eV)
mHH: 0.45mLH: 0.12
mHH: 0.45mLH: 0.082
mHH: 0.28mLH: 0.044
mHH: 0.49mLH: 0.16
hole effectivemass (/m0)
InPGaAsGeSi
17
0.17
mHH: 0.44mLH: 0.016
850
0.014
77000
InSb
14.8
0.36
mHH: 0.57mLH: 0.35
500
0.023
40000
InAs
0.0820.067mt: 0.082ml: 1.467
mt: 0.19ml: 0.916
electron effectivemass (/m0)
2004001900430hole mob.(cm2/Vs)
5400920039001600electron mob.(cm2/Vs)
12.6121611.8permittivity
1.341.420.661.12band gap (eV)
mHH: 0.45mLH: 0.12
mHH: 0.45mLH: 0.082
mHH: 0.28mLH: 0.044
mHH: 0.49mLH: 0.16
hole effectivemass (/m0)
InPGaAsGeSi
S. Takagi, et al., (Tokyo Univ) T-ED, vol. 55, no. 1, p. 21, 2008.
High mobility channel materialsHigh mobility channel materials
Better carrier transport
Higher drive current at low power supply40
ITRS 2011 for Si (HP: High Performance Logic)ITRS 2011 for Si (HP: High Performance Logic)
2012 2016 2018 2020 2022
Lg (nm)
Vdd (V)
EOT (nm)
Mobility enhancementfactor due to strain
CV/I (ps)
BulkFD SOI∗1: MG
Year of Production
∗1: Thicker EOT for MG(Multiple gate : Fin/Tri gate, nanowire)
2024 2026
Cg Ideal(fF/µm)
BulkFD SOI
MGBulk
FD SOIMGBulk
FD SOIMG
Vt,sat (mV)
2014
22 18 15.3 12.8 10.6 8.9 7.4 5.9
0.87 0.82 0.77 0.73 0.68 0.64 0.61 0.570.84 0.73 0.61
0.8 0.72 0.63 0.540.76 0.68 0.62 0.56 0.50 0.45
1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8
0.658 0.611 0.576
0.57 0.47 0.380.38 0.30 0.24 0.20
0.29 0.24 0.19 0.16 0.13 0.10
289 302 310222 227 234 242
217 223 225 228 231 237
0.529 0.429 0.3930.455 0.409 0.362 0.320 0.284 0.238
NMOS
Manufacturing solutionsexist or is being optimized
Manufacturing solutionsare known
Manufacturing solutionsare NOT known41
ITRS 2011 for Si (HP),contdITRS 2011 for Si (HP),contd
2012 2016 2018 2020 2022
Lg (nm)Equivalent
Injection velocity Vinj (107 cm/s)
BulkFD SOI
MG
Year of Production 2024 2026
Id,sat(mA/µm)
BulkFD SOI
MG
BulkFD SOI
MGBulk
FD SOIMG
Rsd (Ω-µm)
2014
CV2
(fJ/µm)
Isd,leak (nA/µm)
22 18 15.3 12.8 10.6 8.9 7.4 5.91.09 1.18 1.33
1.37 1.51 1.63 1.831.68 1.82 2.05 2.26 2.38 2.67
1.685 1.805 1.916 2.030 2.152 2.308
1.6701.367 1.4961.654 1.791 1.9421.530
100 100 100 100 100 100 100 100232 183 149
274 228 187 153257 218 186 160 133 104
0.47 0.38 0.32 0.260.38 0.31 0.25 0.21 0.17 0.14
0.490.68 0.57
Manufacturing solutionsexist or is being optimized
Manufacturing solutionsare known
Manufacturing solutionsare NOT known
42
ITRS 2011 for IIIITRS 2011 for III--V/GeV/Ge
2018 2022 2024 2026
Lg (nm)
Vdd (V)
EOT (nm)Mobility enhancement
factor due tochannel material
Year of Production 2020
14 11.7 9.3 7.4 5.80.63 0.61 0.58 0.56 0.540.68 0.62 0.56
8 8 8 8 80.50 0.45
4 4 4 4 4GeIII-V
0.28 0.24 0.20 0.16 0.130.41 0.36 0.30 0.25 0.21Ge
III-VCg Ideal(fF/µm)
229 230 238 245 251230 231 241 249 254Ge
III-VVt,sat (mV)
0.13 0.11 0.09 0.07 0.060.21 0.17 0.13 0.10 0.08Ge
III-VCV/I (ps)
Manufacturing solutionsare NOT known
43
ITRS 2011 for IIIITRS 2011 for III--V/Ge,ContdV/Ge,Contd
2018 2022 2024 2026
Lg (nm)
Year of Production 2020
14 11.7 9.3 7.4 5.84.29 4.58 5.32 5.93 6.642.26 2.44 2.86 3.19 3.63Ge
III-V
2.200 2.343 2.523 2.703 2.8841.769 1.932 2.121 2.330 2.555Ge
III-V
131 113 96 82 70149 126 105 85 72Ge
III-V
0.18 0.15 0.13 0.11 0.090.23 0.20 0.16 0.14 0.11Ge
III-V
Equivalent Injection velocity
Vinj (107 cm/s)
Id,sat(mA/µm)
Isd,leak (nA/µm) 100 100 100 100 100Rsd
(Ω-µm)
CV2
(fJ/µm)
Manufacturing solutionsare NOT known
44
45
2
1.5
1
0.5
0
Cap
acita
nce
[µF/
cm2 ]
-1 -0.5 0 0.5 1Gate Voltage [V]
10kHz 100kHz 1MHz
20 x 20µm2 1.5
1
0.5
0
Cap
acita
nce
[µF/
cm2 ]
-1.5 -1 -0.5 0 0.5Gate Voltage [V]
20 x 20µm2
10kHz 100kHz 1MHz
2
1.5
1
0.5
0
Cap
acita
nce
[µF/
cm2 ]
-1.5 -1 -0.5 0 0.5Gate Voltage [V]
20 x 20µm2
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
Metal (Silicide) S/D
Extreme scaling in MOSFET Lphy
Dop
antC
onc. δ δGate
σ σ
Met
al C
onc.
Gate
Lphy = Leff- Atomically abrupt junction- Lowering S/D resistances- Low temperature process for S/D
Metal Schottky S/D junctions
- Dopant abruptness at S/D- Vt and ION variation- GIDL
Schottky Barrier FET is a strong candidate for extremely scaled MOSFET S DChannel
S DChannel
n+-Sin+-Si
Metal Silicide
Metal Silicide
48
Surface or interface controlDiffusion species:
metal atom (Ni, Co)Rough interface at silicide/Si- Excess silicide formation- Different φBn presented
at interface- Process temperature
dependent composition
Diffusion species: Si atom (Ti)Surface roughness increases- Line dependent
resistivity change
Line widthof 0.1 µm
H. Iwai et al., Microelectron. Eng., 60, 157 (2002).
Top view
Epitaxial NiSi2
O. Nakatsuka et al., Microelectron. Eng.,83, 2272 (2006).
Si(001) sub.Annealing: 650 oC
49
Si substrate
Ni-silicide
Si substrate
Si substrate
Ni-silicide
Si substrate
Deposition of Ni film
Deposition fromNiSi2 source Annealing Flat interface
Roughinterface
No Si substrateconsumption
Annealing
Deposition of Ni-Si mixed films from NiSi2 source
- No consumption of Si atoms from substrate- No structural size effect in silicidation process- Stable in a wide process temperature range
50
SEM views of silicide/Si interfaces
NiSi2 source
Ni source (50nm)
rough
rough
rough flat
flat
flat
STI 500nm
NiSi2 source (50nm)
500nm
500nm
STI
500nmSTI STI
500nmSTI500nmSTI600oC , 1min
700oC , 1min
800oC , 1min
- Rough interfaces- Consumed Si substrate - Thickness increase ~100 nm
Ni source
- Atomically flat interfaces- No Si consumption- Temperature-independent
Si substrate
Ni-silicide
Ni source
Ni-silicide
Si substrate
NiSi2 source
STI
51
Ideal characteristics (n = 1.00, suppressed leakage current)
Suppressed reverse leakage current- Flat interface and No Si substrate consumption- No defects in Si substrate
Ni
NiSi2
-0.8 -0.6 0.0 0.2Diode voltage (V)
-0.4 -0.210-5
10-4
10-3
10-2
Dio
de c
urre
nt (A
/cm
2 )
1.001.08
n
0.659NiSi2
0.676NiφBn (eV)Source
1.001.08
n
0.659NiSi2
0.676NiφBn (eV)Source
Generation current
RTA:500oC, 1min
Schottky diode structures
Leakage currentAl contact
Ni source
Al contact
NiSi2 source
Si substrate
Si substrate
NiSi2 source Applied Voltage (V)
Cur
rent
den
sity
(A/c
m2 )
52
Ni silicide Ni
200nm
Si Fin
Fins width:20nm50nm
Si Fin Ni silicide
Growth length
SiO2
NWs width:20nm
SiO2 Ni silicide
Ni silicide
Si NW
50nm
200nmGrowthlength
(a) (b)
Wire channel
54
1V0V
0V
S
0V
0V <V<1V
1V0V
0V
0V
0VS D
G
G
G
Suppression of subthreshold leakage by surrounding gate structure
Planar Surrounding gate
Planar Fin Nanowire
Source DrainGate
Wdep
1
Leakage current
S D
Planar FETFin FET Nanowire FET
Because of off-leakage control,1V
0V
0V0V
0VS
D
GG
56
Fin Tri-gate Ω-gate All-around
G G G
G
GNanowire structures in a wide meaning
57
Si nanowire FET as a strong candidate
1. Compatibility with current CMOS process
2. Good controllability of IOFF
3. High drive current
1D ballisticconduction
Multi quantumChannel High integration
of wires
k
E
量子チャネル
量子チャネル量子チャネル量子チャネル
バンド図
Quantum channelQuantum channel
Quantum channelQuantum channel
k
E
量子チャネル
量子チャネル量子チャネル量子チャネル
バンド図
Quantum channelQuantum channel
Quantum channelQuantum channel
Off電流のカットオフ
Gate:OFFDrain Source
cut-off
Gate: OFFdrainsource
Off電流のカットオフ
Gate:OFFDrain Source
cut-off
Gate: OFFdrainsource
Wdep
1
Leakage current
S D
Increase the 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
58
59By Profs. Oshiyama and Iwata, U. of Tokyo
60
λ>>LDiffusive transport
λ<LBallistic transport
λ~LQuasi-Ballistic transport
Lλ :Mean free pathsource drain
Mobility Theory
Real nanoscaleMOSFETs
Compact model for circuit designer is very important
Prof. K. Natori of TIT
61
0
10
20
30
40
50
0 0.1 0.2 0.3 0.4 0.5 0.6
300K VG-Vt=0.1V
300K VG-Vt=0.4V
300K VG-Vt=0.7V
300K VG-Vt=1.0V
4K VG-Vt=0.1V
4K VG-Vt=0.4V
4K VG-Vt=0.7V
4K VG-Vt=1.0V
Current (µA)
Drain Bias (V)
Prof. K. Natori of TIT
62
ポテンシャルプロファイル
チャネル
光学フォノン
初期弾性散乱域 光学フォノン放出可能域
ε~kBT
ε*
ソース
キャリヤ透過確率 Ti
後方弾性散乱が支配後方弾性散乱+(光学フォノン放出)
x00x
V(x)
F(0)
G(0)
( )0
(0) (0)( )
(0)F G
TF
ε=
− ⎞= ⎟
⎠ドレインからの入射透過確率
チャネル内の電子散乱導入の考え方チャネル内の電子散乱導入の考え方
Prof. K. Natori of TIT
63
F(x)/h は、正速度フラックス
G(x)/h は、負速度フラックス( )
( )
0
0
2 ( ) ( ) ( ) 0
2 ( ) ( ) ( ) 0
BdF xqEx F x G xm dx qEx
BdG xqEx G x F xm dx qEx
εε
εε
+ + − =+
− + + − =+
( )
( )
0 0
0 0
22 ( ) ( ) ( ) ( ) 0
22 ( ) ( ) ( ) ( ) 0
B DdF xqEx F x G x F xm dx qEx qEx
B DdG xqEx G x F x G xm dx qEx qEx
εε ε ε
εε ε ε
∗
∗
+ + − + =+ + −
− + + − + =+ + −
( )0
00 0 0 0 0
2( )
2 ln
D qET
qExB D D qE mD Bε
εε
=+⎛ ⎞+ + + ⎜ ⎟
⎝ ⎠
弾性散乱域
光学フォノン放出域
ソースからドレインへの透過確率(エネルギー εに対して)
散乱の導入に係る計算式散乱の導入に係る計算式
物理パラメータB0の値は移動度対応した値
物理パラメータD0の光学フォノンエネルギー緩和時間に対応した値
Prof. K. Natori of TIT
64
0
5
10
15
20
25
30
35
40
0 0.1 0.2 0.3 0.4 0.5
VG-Vt=0.1V, Bal.
VG-Vt=0.1V, Q-Bal.
VG-Vt=0.4V, Bal.
VG-Vt=0.4V, Q-Bal.
VG-Vt=0.7V, Bal.
VG-Vt=0.7V, Q-Bal.
VG-Vt=1.0V, Bal.
VG-Vt=1.0V, Q-Bal.
Current [µA]
Drain Bias [V]
Prof. K. Natori of TIT
65
0.E+00
2.E-05
4.E-05
6.E-05
8.E-05
0.0 0.5 1.0Vd (V)
Id (A
)
Vg – Vth = 1V
0.8V
0.6V
0.4V
0.2V
ExperimentQuasi ballistic
Device fabrication
Si/Si0.8Ge0.2superlatticeepitaxy on SOI
Anisotropicetchingof these layers
Isotropicetchingof SiGe
Gate depositions S/D implantationSpacer formationActivation annealSalicidation
BOXSi
SiGeSi
SiGeSi
SiGeSiN
BOX BOX
BOX
Gate
BOX
Gate
Gate etchingStandardBack-Endof-LineProcess
HfO2 (3nm)TiN (10nm)Poly-Si (200nm)
C. Dupre et al.,IEDM Tech. Dig., p.749, 2008
7
SiN HM
Process Details :
The NW diameteris controllabledown to 5 nm by self limited oxidation.
( )
Cross-section
50nm
SiN HM
Wire direction : <110>50 NWs in parallel3 levels vertically-stackedTotal array of 150 wires EOT ~2.6 nm
NWs
8
3D-stacked Si NWs with Hi-k/MG
BOX
500 nm
Sou
rce
Dra
in
Gate
Top view
<110>
C. Dupre et al.,IEDM Tech. Dig., p.749, 2008
SiNW FET Fabrication
Sacrificial Oxidation
SiN sidewall support formation
Ni SALISIDE Process (Ni 9nm / TiN 10nm)
S/D & Fin Patterning
Gate Oxidation & Poly-Si DepositionGate Lithography & RIE EtchingGate Sidewall Formation
30nm
30nm
30nm
Oixde etch back
Standard recipe for gate stack formationBackend
Lg=65nm, Tox=3nm
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
0.E+00
1.E-05
2.E-05
3.E-05
4.E-05
5.E-05
6.E-05
7.E-05
-1.0 -0.5 0.0 0.5 1.00
10 20 30 40 50 60 70
Dra
in C
urre
nt (µ
A)
Drain Voltage (V)
Vg-Vth=1.0 V
Vg-Vth= -1.0 V
0.8 V
0.6 V
0.4 V
0.2 V
(a)
10-12
Gate Voltage (V)
pFET nFET
(b)
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
Dra
in C
urre
nt (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
0.E+00
1.E-05
2.E-05
3.E-05
4.E-05
5.E-05
6.E-05
7.E-05
-1.0 -0.5 0.0 0.5 1.00
10 20 30 40 50 60 70
Dra
in C
urre
nt (µ
A)
Drain Voltage (V)
Vg-Vth=1.0 V
Vg-Vth= -1.0 V
0.8 V
0.6 V
0.4 V
0.2 V
(a)
10-12
Gate Voltage (V)
pFET nFET
(b)
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
10-3
Dra
in C
urre
nt (A
)
Vd=-50mV
Vd=-1V
Vd=50mV
Vd=1V
On/Off>106、60uA/wire
Recent results to be presented by ESSDERC 2010 next week in Sevile
Wire cross-section: 20 nm X 10 nm
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
(5)
(5)
(10)
(10)(12)
(12x19)
(12)
(12x19)
(13x20)
(9x14)(10)
(10)
(10)
(8)
(8)
(16)
(13)
(34)
(3)(3)
(30)
(19)
VDD: 1.0~1.5 V
括弧内は寸法を示す
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
(5)
(5)
(10)
(10)(12)
(12x19)
(12)
(12x19)
(13x20)
(9x14)(10)
(10)
(10)
(8)
(8)
(16)
(13)
(34)
(3)(3)
(30)
(19)
VDD: 1.0~1.5 V
括弧内は寸法を示す
(12)
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
(5)
(5)
(10)
(10)(12)
(12x19)
(12)
(12x19)
(13x20)
(9x14)(10)
(10)
(10)
(8)
(8)
(16)
(13)
(34)
(3)(3)
(30)
(19)
VDD: 1.0~1.5 V
括弧内は寸法を示す
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
(5)
(5)
(10)
(10)(12)
(12x19)
(12)
(12x19)
(13x20)
(9x14)(10)
(10)
(10)
(8)
(8)
(16)
(13)
(34)
(3)(3)
(30)
(19)
VDD: 1.0~1.5 V
括弧内は寸法を示す
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
(5)
(5)
(10)
(10)(12)
(12x19)
(12)
(12x19)
(13x20)
(9x14)(10)
(10)
(10)
(8)
(8)
(16)
(13)
(34)
(3)(3)
(30)
(19)
VDD: 1.0~1.5 V
括弧内は寸法を示す
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
010203040506070
1 10 100 1000Gate Length (nm)
I ON
(µA
/ w
ire)
nMOSpMOS
(5)
(5)
(10)
(10)(12)
(12x19)
(12)
(12x19)
(13x20)
(9x14)(10)
(10)
(10)
(8)
(8)
(16)
(13)
(34)
(3)(3)
(30)
(19)
VDD: 1.0~1.5 V
括弧内は寸法を示す
(12)
本研究で得られたオン電流
(10x20)102µA
Our Work
Bench Mark
Y. Jiang, VLSI 2008, p.34H.-S. Wong, VLSI 2009, p.92S. Bangsaruntip, IEDM 2009, p.297C. Dupre, IEDM 2008, p. 749S.D.Suk, IEDM 2005, p.735G.Bidel, VLSI 2009, p.240
Si nanowireFET
Planer FETS. Kamiyama, IEDM 2009, p. 431P. Packan, IEDM 2009, p.659
1.2~1.3V
1.0~1.1V
Lg=500~65nm
IIONON/I/IOFF OFF Bench markBench mark
This work
72
0
2
4
0
2
40
5
10
15
x 1019
x (nm)y (nm)
Electron density (/cm3)
024681012
02
46
810
120
5
10
15
x 1019
x (nm)y (nm)
Electron density (/cm3)
(a) (b) width=12nmwidth=4nm
0
2
4
0
2
4500
550
600
650
x (nm)y (nm)
Mobility (cm2/Vs)
024681012
02
46
810
12700
750
800
850
900
x (nm)y (nm)
Mobility (cm2/Vs)
(a) (b) width=12nmwidth=4nm
0
2
4
0
2
4500
550
600
650
x (nm)y (nm)
Mobility (cm2/Vs)
024681012
02
46
810
12700
750
800
850
900
x (nm)y (nm)
Mobility (cm2/Vs)
(a) (b) width=12nmwidth=4nm
0 .E + 0 0
1 .E + 1 9
2 .E + 1 9
3 .E + 1 9
4 .E + 1 9
5 .E + 1 9
6 .E + 1 9
0 2 4 6 8Distance from SiNW Surface (nm)
6543210
角の部分
平らな部分
電子濃度(x1019cm-3)Electron Density
Edge portion
Flat portion
0
2000
4000
6000
8000
10000
12000
2008 2010 2012 2014 2016 2018 2020 2022 2024 2026
Year
I ON
(µA/µm
)
SiNW (12nm×19nm)
MGFDbulk
ION∝Lg-0.5×Tox
-1(20)
(11)
(33)
(15)
(26)
今回用いたIONの仮定
1µm当たりの本数
コンパクトモデルの完成
S/D寄生抵抗低減技術
pMOSの高性能化
低EOT実現技術
Compact model
Small EOT for high-k
P-MOS improvement
Low S/D resistance
# of wires /1µm
Assumption
ITRSNan
owire
Primitive estimation !
76
Conclusions
MOSFET is the most fundamental and smallest functional device available for manufacturing.
It is really amazing to keep the evolution for so many generations without being replaced by any other device.
77
The device downsizing of MOSFET will be ended within 10 - 20 years because many of the device parameters are now approaching the physical and manufacturing limits. Even after the end of MOSFET downsizing, CMOS technology will still be the mainstream IC technology for a long period, as no other device technology can be developed into a comparable integration scale as the present CMOS technology in foreseeable future.
Thank you for your attention!
78