material engineering for 7nm finfets · 11/21/2013  · © 2014 synopsys. all rights reserved. 5...

© 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

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Intel Investor Meeting, Nov. 21, 2013

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© 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

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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

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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

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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

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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

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Outline

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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 %

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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)

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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

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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

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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

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Outline

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IdVg After Work-Function Adjustment

3D analysis in S-Device

GaAs

InAs BTBT

• BTBT model

calibrated by

IMEC

• Vdd = 0.7 V

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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

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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