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1/61W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes

1I. II. -III. IV. V. VI.VII.CMP

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I.

1):contact, interconnection, connection to outside

2) IC:yield, reliability

3) system(1)(2)(3)

1.

2.1)

(1):,,,

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(2):(3)(4):,(5) bondability :

2)(1): Pt-Si, Al (2):(3)( 3,000 4,000 ppm/)

Al Cu Au Mo Pt Ag Ta Ti W

2.8 1.7 2.44 5.7 10.5 1.46 13.0 55 5.5

3)(1) step coverage, electromigration

(2) corrosion, oxidation,,

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1) Al : electromigration, corrosion 2) Al + 2% Si

3) Al + 2% Si + 4% Cu

4) Pt - Si

5) Pt(700) : Si - Ti(1000) - Pt(2000) - Au(1mil)Pt(700)Pt-Si(sintering)Pt

Ti

(1000

)Pt(2000)Au(1mil)

6) Mo, Ta, W-Au, Cu-Au, Ti-Au,

3.

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properties Al Au Mo Pt Ta W

deposition evap. evap. sputter or CVD from fluorides

compatibility G - G G G G

adherence G N G - G G

delineation G N Y D D D

bondability G G N N N N

contact resistance G - H B H H

conductivity 2.7 2.44 5.4 10.5 27 5.5

surface coverage depends on deposition condition

electromigration resistance F B G G G G

corrosion resistance F B F G G Gstability G G G G G G

process temperature() 500 - 800 - 800 800

: G(good), N(no), Y(OK), D(difficult), H(high), B(best), F(fair)

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1.1) Schottky2) Ohmic:tunneling

2.1) n

II. -

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eV1.4qM

eV95.0qox

eV8EgeV15.4q

Si

eV5q s

SiFE

cE

vE

MFE

aluminum silicon oxide silicon

cE

vE

2) M-O-S

< Na=21015/cm3pAl>

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3) doping

, Si : B : VR : N :

BN?

)V(Nq

2

C

1

V

Nq

2

1

WC

RB

Si

2

2

1

RB

SiSi

21

RBSi

qN

)V(2W

for step junction

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W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes

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3.1) N

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(1) Schottky diodeI-V

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< Al/n-Si SchottkyI-V>

2) Schottky diodeI-V

Schottky diode(IR=10-6A): Si step junction

60%

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2) 51017/cm3< N < 1019/cm3 :

3) N>1019/cm3: tunneling currentOhmic contact(1):

N1

expW

1exp

dI

dVAR

0v

c

2) Al-silicon

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III.1.(CVD)

1) better uniformity, better step coverage2) Al: 6005003) 90CVD: W, Mo4) Al CVD

2.1): filament, e-beam, RF, flash, sputtering(1)

- : 1 torr 710-6cm (for N2) 10-3torr 5 cm (for N2) 0.5 (for electron)

- - 10-6torr

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(2) filament, RF e-beam, flash

(3) filament

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heater : W, Ta, Mo, Pt()heater

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tight beamdiffuse beam

pure metalrefractory metalalloyx-ray

(6)

alloywire feeding,e-beam20%

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2)(1)

chamber step coverage(Ar 1-10 mtorr) cleaning

(2):,(DC)

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3.1) in-situ thickness monitor

(1) crystal monitor

(2) interferometer : laser

DA

MTDATDVM

MK

P

K

M

fP

M

Kf

===

=

===

1

1,

f :M:K:P:D:T:A:

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2)(1).(2).(3).(4).(5) 510-6torr.(6).(7).(8).(9).

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3)(1):,,,,,

grain, roughness,(2): stylus(3)

: 4-point probe4) Na+: HTB C-V

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IV. 1.

1) grain size2) Al2O3: T>250,10-810-5 torr

PTRG

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3) hillock(1):(2) hillock: edge, flat-topped, spike hillock(3):Alstressstrain

stress: Si (3.3 ppm/), Al (23.6 ppm/)

(Te)(Ta)strain

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(4) hillockself-diffusion rate: Sn, Cd, Insite: Sihillock:

Te(

) Ta(

) Dcycled(/cm2

) Duncycled (/cm2

)23 430 8.7107 4.0 107200 430 1.5 106 5.0 105400 430 3.4 104 6.0 10327 223 6.0 106 3.2 106200 179 5.2 105 2.8 105400 237 0 0

1) uncycled : RT Ta, 2) cycled : RT Ta

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2.1) : 10

-5

cm2

/2525 m22) : 500, 10 min. 450, 30 min.3) : Al (2.65 cm), Al-Si (1%) (3.0 cm)4) > 0.002 ( 51019dopants/cm3) rectifying contact

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(cm) ( cm)Au 2.35 Al-Ni(1%) 2.75Al 2.65 Al-Si(1%) 3.0

Mo 5.7 Al-Ti(1%) 5.53

Pt 10.6 Al-Cr(1%) 5.78

Ti 55.0 Al-Pt(1%) 2.9

Cu 1.7 Au-Ni(10%) 10.2

3.1) : O2, H2O, H2, N2, CH42) : H2O, O2

2Al + 3O2 = 2Al2O3

3) :3SiO2+ 2Al 2Al2O3+ 3Si (Alalloy)

22322 H

2

3)OHOAl(

2

1OH2Al

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oxide

heat of formation(kcal/mole)

oxideheat of formation

(kcal/mole)

Ta2O5 -500 WO3 -200

Al2O3 -399 MoO3 -180

V2O3 -290 Cu2O -40

Cr2O3 -270 Ag2O -7

TiO2 -218 Au2O3 +19

SiO2 -205 - -

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4.Coverage1) shadowing : slope, geometric, self shadowing

shadow:

Dh)XL

21( o=

})X(0.5LD/{arctan o>

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2) shadowing deposition system

biaxial planetary source source-substrate

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5. Adhesion1) SiO

2

2): tape(3M)

materials shearing force (108dynes/cm2) adherence to SiO2

FeSi 37 weak

CoSi 120 strongCoSi2 70 intermediate

PtSi2 170 very strong

Al 170 very strong

Ti 170 very strongAu - very weak

Co 54 intermediate

Mo 113 strong

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6.1):, low cost, high conductivity, good adhesion,

easy patterning, low contact resistance

Al-Si alloy, good bondability,.

2): difficult CVD deposition,electromigration, corrosion, hillock formation

Al-AuSi into Al grain boundary reliability

siliconstress,

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V.1. Double metal

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(1) 1st metal

Al, Al-Si, Al-Cu, Al-Si-Cu

Al : e-beam, sputteringAl-Si : double gun e-beam, sputtering

Al-Si-Cu : flash, sputtering(2) 1st insulator SiO2, Si3N4, Al2O3, Ta2O5, WO2, PSG: CVD, sputtering

(3) 2nd metal

Al1st metal(4) passivation

PSG : 3%, 0.8~1m,85 /sec : 35 /sec for PSG : CVD()

1)

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2)(1) sharp edge :

1st &2nd metalshort 2nd metal crack reliability

(2) hillock Al deposition(380) PSG deposition (200) , alloy (450)

(3) SiO2: chamber, Al film.(4)(rework)

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(5) sharp edge

: hard baking

etch

Al hillock:, Al-Si PECVD SiO2deposition :CVD systemSiO2contamination.

(6) : polymide plasma etching

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2.1)

2): (,,)(,)

(,)

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3)(1):,

5000(2):,,

m(1Al 1.65Al2O3)

4)

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(1):(2)

(3)Faraday

V:, :, F: 96500 C/mole, m=6, S:,H:

M: mole, Q:, :,J:

Fm

MJ

dt

dH

dt

dQ

Fm

M

dt

dHS

dt

dV

Fm

MQV

==== ,,

high voltage low voltage

electrolyte 4 % H3PO4 4 % H2SO4operating voltage 133 20

barrier layer thickness() 1,500 250

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VI.1.-

1) eutectic point 5771.6%2) 3500.1%

3)Al spike alignmentpackaging (111)(110)36

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4) spike(1): step coveragetrade off(2)Al(3) 200(4) barrier metal: Ti, W, Ta, Ti-W -trade off(5)(6) Al-2% Si

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2.1) : bipolar

MOS2) :Na+

barrier(Si3N4, Al2O3, PSG)

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3. Electromigration1)

q :q* :: q* = 20 30q

2)

/kT)Wexp(DkT

JNqNEF

/kT]Wexp[DD

q

kT

DE,J

NENEX

NDF

s0

*

s0

*

==

=

==

=+

=

AlintoAlofdiffusionself:

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3)(1): temperature gradient(2) diffusion: surface diffusion

grain boundary diffusionbulk diffusion

(3): grain,: D

o, W

s, J

stepcurrent crowding4) ElectromigrationMTF

(1) MTF

)exp()exp()exp(MTFkT

W/L

Jn

WT/L

F

A s=

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(2) MTF

, W: AlT: Aln: 1 (contact)2~3()

MTF Ws(eV)

grain size: large (>3 m) 2 ~ 3 0.5 ~ 0.6small (

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VII. CMP1.

1)2) 1980,3), MOSFET4)

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2. CMP1)2)

3) () ()

4)nm

planarization) Damascene)

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3. CMP1)

:, :, : : :

polishing pad

slurrydispenser

platen

chuck

wafer

spindle

CMP

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2)

:um

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3):+:pH:: SiO2, Al2O3, CeO2CMP:+ Al2O3 CMP

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4) CMP:,,,:,,,, pore,

5) CMP

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4. CMP1)

->

SiO2: SiO2-> Si(OH)4 W: W -> WO3

Cu: Cu -> Cu2O2)

:::

kp (), P (), v (), E (Young)

1/ (2 )p pR k Pv k E= =

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5. CMP1)

STISi3N4

stopping layer)

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1) Trench Definition: Buffer Oxide Growth, Nitride Deposition,Isolation Lithography

2) Trench Etch: Nitride Etch, Oxide Etch, Silicon Etch

3) Photoresist Strip

4) Thermal Oxidation

5) CVD Oxide Fill

6)Chemical Mechanical Polish

7) Nitride Etch

STI

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2)CMP: (contact)(via)(plug)CMP:CMP

7

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6.1):

ITRS 2010)Year 2010 2013 2016 2019 2022

MPU/ASIC Metal 1 (1/2 pitch) 45 27 18.9 13.4 9.5

Dielectric Constant (ILD) 2.3~2.5 2.1~2.3 1.9~2.1 1.7~1.9 1.5~1.7

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2) SiO2 (k > 2.7): (k < 2.7): tetramethoxysilane(TMOS)tetraethoxysilane(TEOS)-

:(air gap)3)

,/,, , CMP,,,,,,

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7.1)

:,,

2):(1.7ucm),electromigration,,,

:,, ,

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3):: via filling

4) : via trench

. ..(adhesion) (barrier) . .

. CMP.

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. a), b),c), d), e)CMP

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6금속공정_20111229151922 al, cu, au coreano