© 2014 Synopsys. All rights reserved. 1
Material Engineering
for 7nm FinFETs
Victor Moroz
July 10, JTG Semicon West 2014,
San Francisco
© 2014 Synopsys. All rights reserved. 2
Outline
© 2014 Synopsys. All rights reserved. 3
Outline
© 2014 Synopsys. All rights reserved. 4
Evolution of Transistor Scaling
1
10
100
1000
Siz
e, n
m
Leff
L=Node
L used to be in sync
with technology node L quickly accelerated
then saturated Will fall behind
© 2014 Synopsys. All rights reserved. 5
Intel Investor Meeting, Nov. 21, 2013
© 2014 Synopsys. All rights reserved. 6
© 2014 Synopsys. All rights reserved. 7
Expected Design Rules
Node Gate
pitch L
Spa-
cer
Fin
width
Fin
height Fin pitch
Contact
size EOT
10 63 20 11 8 32 34 21 0.85
7 44 15 7 6 30 24 15 0.8
All sizes are in nm
© 2014 Synopsys. All rights reserved. 8
Stress Engineering at 14 nm Node
• Main stress source is SiGe PMOS source/drain epitaxy
Junct
ion
Si
NMOS: Low Stress PMOS: High Stress
Si
© 2014 Synopsys. All rights reserved. 9
Common SRB Epi for NMOS & PMOS
• Considering cell heights (pitches) of 360 nm, it is impractical to have separate
SRB’s for NMOS and PMOS
Si wafer Si wafer
SiGe SRB
NMOS PMOS PMOS
SiGe SRB
Standard
cell row
Another
cell row Wafer before fin patterning
SiGeSn Ge channel
© 2014 Synopsys. All rights reserved. 10
Si channel SiGe channel Ge channel
NMOS
+1.5 GPa
PMOS
-1.5 GPa
7nm Stress Engineering: SRB + S/D Epi
Stress analysis in S-Process
Si Si
Si Ge
Ge
25% Ge
25% Ge
50% Ge
50% Ge
75% Ge
75% Ge
50%
Ge
50%
Ge
15%
Ge
85%
Ge
70%
Ge
30%
Ge
Ge
© 2014 Synopsys. All rights reserved. 11
Ballistic Transport Evolution
• Ballistic transport is
currently ~64%
• Is expected to rise to
~84% at 7nm node
• Even higher for Ge and
InGaAs
• Therefore, ballistic
transport approximation
is reasonable for 7nm
node
Calculated in Sentaurus Monte Carlo
14nm
5nm technology node
10nm
7nm
Si NMOS FinFET with 6nm wide fin
0.85
0.77
0.70
0.64
0.53
0.32
0.11
0.90
0.84
0.77
0.71
0.61
0.41
0.16
0.0
0.2
0.4
0.6
0.8
1.0
10 100
Ball
isti
c R
ati
o
Channel Length, nm
Relaxed
2 GPa
© 2014 Synopsys. All rights reserved. 12
Outline
© 2014 Synopsys. All rights reserved. 13
Stress Free SiGe: IdVg Curves
3D analysis in S-Device
• Vdd = 0.7 V in this
project
• BTBT model
calibrated by IMEC
Dra
in c
urr
en
t, A
/um
Gate bias, V
Ge
Si
Higher Ge %
© 2014 Synopsys. All rights reserved. 14
Strained SiGe: 2 GPa Tensile Stress
7nm NMOS FinFET
722 638
1,233 1,310
970
1,054
1,900 2,003
1,902
2,429
0
500
1000
1500
2000
2500
3000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Germanium mole fraction
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
HP: 100 nA/um
(Servers)
SP: 1 nA/um
(Laptops)
LP: 50 pA/um
(Mobile)
© 2014 Synopsys. All rights reserved. 15
Strained SiGe: 2 GPa Tensile Stress
7nm NMOS FinFET
722 638
1,233 1,310
970
1,054
1,900 2,003
1,902
2,429
0
500
1000
1500
2000
2500
3000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Germanium mole fraction
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
Flat Dip
Best
Gone
HP: 100 nA/um
SP: 1 nA/um
LP: 50 pA/um
© 2014 Synopsys. All rights reserved. 16
Strained SiGe: Ninv and Vinj
7nm NMOS FinFET
0.0E+00
2.0E+12
4.0E+12
6.0E+12
8.0E+12
1.0E+13
1.2E+13
0 0.2 0.4 0.6 0.8 1
Inve
rsio
n c
harg
e, 1
/cm
2
Germanium mole fraction
SiGe (2GPa) LP
SiGe (2GPa) SP
SiGe (2GPa) HP
0.E+00
1.E+07
2.E+07
3.E+07
0 0.2 0.4 0.6 0.8 1
Inje
cti
on
ve
loc
ityj, c
m/s
Germanium mole fraction
SiGe (2GPa) LP
SiGe (2GPa) SP
SiGe (2GPa) HP
© 2014 Synopsys. All rights reserved. 17
0%
20%
40%
60%
80%
100%
0 0.2 0.4 0.6 0.8 1
Va
lle
y o
cc
up
an
cy %
Germanium mole fraction
Delta & Lambda Valley Population
S-Band
• Here, Vgs = 0.7 V and gate WF is adjusted to have min Ioff at Vgs = 0
• There are too few electrons at 80% to 90% Ge mole fractions
0.0E+00
5.0E+11
1.0E+12
1.5E+12
2.0E+12
0 0.2 0.4 0.6 0.8 1
Nin
v (
1/c
m2
) Germanium mole fraction
X L Relative
Absolute X
L
© 2014 Synopsys. All rights reserved. 18
Strained SiGe: LP, SP & HP Champions
7nm NMOS FinFET
722 638
1,233 1,310
970
1,054
1,900 2,003
1,902
2,429
0
500
1000
1500
2000
2500
3000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Germanium mole fraction
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
LP: Si
SP: Mid-range SiGe
HP: Ge
© 2014 Synopsys. All rights reserved. 19
722 638
1,233 1,310
970
1,054
1,900 2,003
1,902
2,429
0
500
1000
1500
2000
2500
3000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Germanium mole fraction
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
Strained SiGe: Combination Champion
7nm NMOS FinFET
• Only Si and SiGe
with low Ge % can
match LP spec
• HP performance
penalty to pure Ge is
~20%
• The choice between
pure Si vs SiGe with
low Ge % can be
made based on
PMOS/NMOS stress
trade-off
Better PMOS s
Better NMOS s
© 2014 Synopsys. All rights reserved. 20
Outline
© 2014 Synopsys. All rights reserved. 21
IdVg After Work-Function Adjustment
3D analysis in S-Device
GaAs
InAs BTBT
• BTBT model
calibrated by
IMEC
• Vdd = 0.7 V
© 2014 Synopsys. All rights reserved. 22
Leakage Patterns
Vgs = -0.3 V
InAs GaAs BTBT is spread
along junction
GIDL happens
at the fin top
© 2014 Synopsys. All rights reserved. 23
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 0.2 0.4 0.6 0.8 1
Ban
dg
ap
, e
V
Gallium mole fraction
Bulk
Narrow fin
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0 0.2 0.4 0.6 0.8 1
Ban
dg
ap
, e
V
Germanium mole fraction
BulkStrained narrow finStress-free narrow fin
Band Gap Widening and Narrowing
7nm NMOS FinFET
• For SiGe, 6nm wide fin widens bandgap by 40 mV to 50 mV
• Tensile uniaxial 2 GPa stress pushes it down by 70 mV to 100 mV
• For GaAs, the widening is 155 mV, and for InAs it grows to 340 mV
SiGe InGaAs
co
nfinem
en
t str
ess
co
nfinem
en
t
© 2014 Synopsys. All rights reserved. 24
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 0.2 0.4 0.6 0.8 1
Ban
dg
ap
, e
V
Gallium mole fraction
Bulk
Narrow fin
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0 0.2 0.4 0.6 0.8 1
Ban
dg
ap
, e
V
Germanium mole fraction
BulkStrained narrow finStress-free narrow fin
Band Gap Widening and Narrowing
7nm NMOS FinFET
• High mobility materials need to have bandgap wider than silicon!
SiGe InGaAs
co
nfinem
en
t str
ess
co
nfinem
en
t
LP Ioff spec
© 2014 Synopsys. All rights reserved. 25
0%
20%
40%
60%
80%
100%
0 0.2 0.4 0.6 0.8 1V
all
ey o
cc
up
an
cy %
Gallium mole fraction
Gamma, Delta & Lambda Valleys
7nm NMOS FinFET
0%
20%
40%
60%
80%
100%
0 0.2 0.4 0.6 0.8 1
Va
lle
y o
cc
up
an
cy %
Germanium mole fraction
G
L
SiGe InGaAs
X
L
© 2014 Synopsys. All rights reserved. 26
Group IV vs III-V: Ninv and Vinj
7nm NMOS FinFET
0.0E+00
2.0E+12
4.0E+12
6.0E+12
8.0E+12
1.0E+13
1.2E+13
0 0.2 0.4 0.6 0.8 1
Inve
rsio
n c
ha
rge
, 1
/cm
2
Mole fraction (Germanium or Gallium)
InGaAs LP InGaAs SP InGaAs HP
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
0.E+00
1.E+07
2.E+07
3.E+07
4.E+07
5.E+07
6.E+07
0 0.2 0.4 0.6 0.8 1
Inje
cti
on
ve
loc
ityj,
cm
/s
Mole fraction (Germanium or Gallium)
© 2014 Synopsys. All rights reserved. 27
Group IV vs III-V
7nm NMOS FinFET
601
199
1,977
754
2,449
2,612 2,589
722 638
1,233 1,310
970
1,054
1,900
2,003 1,902
2,429
0
500
1000
1500
2000
2500
3000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Mole fraction (Germanium or Gallium)
InGaAs LP InGaAs SP InGaAs HP
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
© 2014 Synopsys. All rights reserved. 28
Group IV vs III-V: LP, SP & HP Champions
7nm NMOS FinFET
601
199
1,977
754
2,449
2,612 2,589
722 638
1,233 1,310
970
1,054
1,900
2,003 1,902
2,429
0
500
1000
1500
2000
2500
3000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Mole fraction (Germanium or Gallium)
InGaAs LP InGaAs SP InGaAs HP
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
LP: Si
SP: 30% In InGaAs
HP: Mid-range InGaAs
© 2014 Synopsys. All rights reserved. 29
Group IV vs III-V: Combination Champion
7nm NMOS FinFET
601
199
1,977
754
2,449
2,612 2,589
722 638
1,233 1,310
970
1,054
1,900
2,003 1,902
2,429
0
500
1000
1500
2000
2500
3000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Mole fraction (Germanium or Gallium)
InGaAs LP InGaAs SP InGaAs HP
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP• Only Si, low Ge
SiGe, and GaAs can
match LP spec
• InGaAs with 10% In
has competitive
performance, but is
too sensitive to In
content
• This would bring
severe variability
• So, silicon looks the
best…
• SiGe with low Ge %
can be used for
stress engineering
© 2014 Synopsys. All rights reserved. 30
1,090
1,064
689
1,510
1,962
1,651
1,211
694
30 27
331 364
112
239
1,131
1,239
1,082
1,547
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 0.2 0.4 0.6 0.8 1
Ion
, u
A/u
m
Mole fraction (Germanium or Gallium)
InGaAs LP InGaAs SP InGaAs HP
SiGe (2GPa) LP SiGe (2GPa) SP SiGe (2GPa) HP
0.5 V Vdd Instead of 0.7 V Vdd
7nm NMOS FinFET
• InGaAs with 30% In
really shines at SP
and HP specs
• Nobody can pull off
LP at 0.5 V Vdd.
Would you like your
iPhone to be ~30x
slower?
• To have 0.5 V Vdd,
variability has to go
down ~2x. That is a
stretch.
• The best InGaAs
composition has Si-
like bandgap
© 2014 Synopsys. All rights reserved. 31
Summary
• It is a close race, no clear winner
• The best choice depends on particular chip spec
7nm NMOS FinFET