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MURI PlansMURI Plans

S. E. Thompson March 27, 2005

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TI Fellows Forum

OUTLINEOUTLINE

• SRC and AMD, AMAT, IBM, Intel, TSMC, TI, UMC funded device modeling/characterization work

• Plans: Single event transient– Start with SRC strained Si modeling/calibration– SET on State-of-the-art uniaxial strained Si (90-45nm)– SET on Future strained devices

• Strained Ge transistor• Strained Si and Ge on (110) wafers

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TI Fellows Forum

1-2.5GPa stress film

Post salicide

Si1-xGex

45nm

Si1-xGex

Removable film pre-anneal

Nitride

Gate Gatestress stressa-Si a-Si

Many Ways to Do StrainMany Ways to Do Strain

Even more on high stress layers

Intel 2004 EDLTI 2004 VLSIAMAT 2004 IEDMIBM 2005 VLSITSMC/Freescalse 2005Samsung 2005 VLSI

Hoyt

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Strain Being Adopted by AllStrain Being Adopted by All

Si1-xGex

p-type MOSFET

Si1-xGex

Strained Si45 nm

stress stress

NMOS PMOS

Gate

STI

Tensile Nitride Compressive Nitride

Gate

FujitsuSource: Ti

Source Chipworks: 90 nm Intel,IBM,AMD,TI,Fujitsu

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Why Strain: Very Impressive Performance Why Strain: Very Impressive Performance

2004 IEDM Intel

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Significantly Alters Band Structure/Transport

E

K <110>

HeavyHole

Light Hole

UniaxialLongitudinal Compression

Biaxial Tension

Uniaxial Longitudinal Tension

Valance Band warping, changes m*,

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TI Fellows Forum (μm)

(μm

)

45 nm

140

nm

120

nm

30 nm

Si0.83Ge0.17Si0.83Ge0.17

STI STI

-536

-83403

95

31

Stress ContoursStress Contours

Source FLOOPs

MPa

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Device Level Calibration: SRC/Intel FundedDevice Level Calibration: SRC/Intel Funded

• Industrial samples– 30 nm to 1um Si trasistors from 3 companies– Unstressed, uniaxial and biaxial stressed wafer– Bulk and SOI– Fully depleted SOI /Metal Gate– High k/metal gate and sub-micron Ge channel devices

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Four-Point Bending Set-UpFour-Point Bending Set-Up

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-50-40-30-20-10

01020304050

-500 -300300 500

Stress / MPa

Mob

ility

Enh

ance

men

t (%

)

Uniaxial Longitudinal

SiGe S/D [4]

Uniaxial Transverse

Biaxial

Biaxial Rim

DataModel

Strain Enhanced Mobility: Strain Enhanced Mobility: Model / MeasuredModel / Measured

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6 Band K P Including Confinement6 Band K P Including Confinement

( ) ( )[ ] ( ) ( ) ( )zkEzzVzkH kkvv

vvψψ =+,

( )

⎥⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢⎢

⎣

⎡

=

⎥⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢⎢

⎣

⎡

⎥⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢⎢

⎣

⎡

+

−

+

−

++−

+−

+−−

.

.

.

.

.......

.ˆˆˆ00.

.0ˆˆˆ0.

.00ˆˆˆ.

.......

1

1

1

1

1

1

i

i

i

i

i

i

i

i

i

KEHHH

HHHHHH

ψψ

ψ

ψψ

ψ v

Schrodinger’s Equation and Poisson’s Equation solved self-consistently using the Finite-Difference Method.

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Si and Ge Band StructureSi and Ge Band Structure

GeSi

No Stress

Biaxial Stress

Longitudinal compression

HH LH HH LH

Top Bottom Top Bottom

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In and Out-of-Plane Masses (Ge)In and Out-of-Plane Masses (Ge)

m||

m|

m||

m|

kzkz

kyky

Uniaxial StressBiaxial Stress

kx kx

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Si and Ge Band Structure on (100) and (110)Si and Ge Band Structure on (100) and (110)

Si GeLongitudinal compression

Top Bottom Top Bottom

(100)

(110) hybrid

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TI Fellows Forum

( )

( )

∫∂∂

=π

φ

ν

ν

φφπ

2

0

,

,21)(

EKKE

EKdEg

Si is confined in kz direction. 2-dimensional density of state is given by:

And total charge density over all possible bands:

( )( )∑∫

∞

⎟⎟⎠⎞

⎜⎜⎝⎛ −++

=ν ν

0 0

exp1Tk

EEEEgdEp

B

F

Full Transport Model: Calculation of Full Transport Model: Calculation of Density of StatesDensity of States

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Density of States MassDensity of States Mass

0.1 1 10 0

0.5

1

1.5

2

2.5

3

Stress / GPa

Effe

ctiv

e M

ass

m*/

m0

Longitudinal compressive

Biaxial tensile

Production level stress

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TI Fellows Forum

Summary / Next StepsSummary / Next Steps

• First-principles quantum mechanical methods for strained Si band structure

• Spatially dependent strain-induced band structure

• Model charge transport and collection due to single event in FLOOPS/FLOODS– Start with existing MURI developed models– Add strain for Si and Ge transistors