vi. vii. cmpocw.sogang.ac.kr/rfile/2011/course10-spt/6금속공정... · 2011-12-29 · pt 증착...

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

1

I.

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 G

stability 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) Schottky 2) Ohmic : tunneling

2. 1) n

II. -


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eV1.4q M =

eV95.0q ox =

eV8Eg

eV15.4q Si =eV5q s =

SiFEcE

vE

MFE

aluminum silicon oxide silicon

cE

vE

2) M-O-S

< Na=21015/cm3 p Al >


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3) doping

, Si : B : VR : N : B N ?

)V(Nq

2C1

VNq

21

WC

RBSi

2

21

RB

SiSi

=

=

=

21

RBSi

qN)V(2W

= for step junction


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3.

1) N


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(1) Schottky diode I-V


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< Al/n-Si Schottky I-V >

(2) Schottky diode I-V

Schottky diode (IR=10-6 A): Si step junction 60%


12


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

3) N>1019/cm3 : tunneling current Ohmic contact

(1) :

=

N1exp

W1exp

dIdVAR

0vc

(2) Al-silicon


14


15

III.

1. (CVD) 1) better uniformity, better step coverage 2) Al : 600 500 3) 90 CVD : W, Mo 4) Al CVD

2. 1) : filament, e-beam, RF, flash, sputtering

(1) - :

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

- - 10-6 torr


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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 beam diffuse beam

pure metal refractory metal alloy x-ray

(6) alloy wire feeding , e-beam 20%


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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

DAMTDATDVM

MK

P

KM

fP

MKf

===

=

===

1

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


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2)

(1) .

(2) .

(3) .

(4) .

(5) 510-6 torr .

(6) .

(7) .

(8) .

(9) .


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3)

(1) : , , , , ,

grain, roughness,

(2) : stylus

(3) : 4-point probe

4) Na+ : HTB C-V


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IV.

1.

1) grain size

2) Al2O3 : T>250, 10-810-5 torr P

TRG


24


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3) hillock (1) : (2) hillock : edge, flat-topped, spike hillock (3) : Al stress strain

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

(Te) (Ta) strain


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(4) hillock self-diffusion rate : Sn, Cd, In site : Si hillock :

Te() Ta() Dcycled(/cm2) Duncycled (/cm2)

23 430 8.7107 4.0 107

200 430 1.5 106 5.0 105

400 430 3.4 104 6.0 103

27 223 6.0 106 3.2 106

200 179 5.2 105 2.8 105

400 237 0 0

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


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2. 1) : 10-5 cm2/2525 m2

2) : 500, 10 min. 450, 30 min. 3) : Al (2.65 cm), Al-Si (1%) (3.0 cm) 4) > 0.002 ( 51019 dopants/cm3 ) rectifying contact


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(cm) ( cm) Au 2.35 Al-Ni(1%) 2.75 Al 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, CH4 2) : H2O, O2 2Al + 3O2 = 2Al2O3

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

22322 H23)OHOAl(

21OH2Al +=+


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oxide heat of formation (kcal/mole) oxide heat 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. Coverage 1) 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. Adhesion 1) SiO2 2) : tape(3M)

materials shearing force (108dynes/cm2) adherence to SiO2 FeSi 37 weak CoSi 120 strong CoSi2 70 intermediate PtSi2 170 very strong

Al 170 very strong Ti 170 very strong Au - 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-Au

Si into Al grain boundary reliability

silicon stress,


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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, sputtering Al-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 Al 1st 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 metal short 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 SiO2 deposition : CVD system SiO2

contamination . (6) : polymide plasma etching


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2. 1)

2) : (, , ) (, ) (, )


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3) (1) : , 5000 (2) : , , m (1 Al 1.65 Al2O3) 4)


40

(1) : (2) (3) Faraday

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

FmMJ

dtdH

dtdQ

FmM

dtdHS

dtdV

FmMQV

==== ,,

high voltage low voltage electrolyte 4 % H3PO4 4 % H2SO4 operating voltage 133 20 barrier layer thickness() 1,500 250


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VI.

1. - 1) eutectic point 577 1.6% 2) 350 0.1% 3) Al spike

alignment packaging (111) (110) 36


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4) spike (1) : step coverage trade 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

MOS 2) : Na+

barrier (Si3N4, Al2O3, PSG)


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3. Electromigration 1) q : q* : : q* = 20 30q 2)

/kT)Wexp(DkTJNqNEF

/kT]Wexp[DDqkT

DE,J

NENEXNDF

s0*

s0

*

==

=

==

=+

=

AlintoAlofdiffusionself:


45

3) (1) : temperature gradient (2) diffusion: surface diffusion grain boundary diffusion bulk diffusion (3) : grain , : Do, Ws, J step current crowding 4) Electromigration MTF (1) MTF

)exp()exp()exp(MTFkTW/L

JnWT/L

FA s=


46

(2) MTF

, W : Al T : Al n : 1 (contact) 2~3()

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


47

VII. CMP

1. 1)

2) 1980 , 3) , MOSFET

4)


48

2. CMP 1) 2)

3) () ()

4) nm

(planarization) (Damascene)


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3. CMP 1)

: , : , : : :

polishing pad

slurry dispenser

platen

chuck

wafer

spindle

CMP


50

2)

: um


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3) : + : pH: : SiO2, Al2O3, CeO2 CMP : + Al2O3 CMP


52

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

5) CMP


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4. CMP 1)

->

SiO2: SiO2 -> Si(OH)4 W: W -> WO3 Cu: Cu -> Cu2O

2) : : :

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

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


54

5. CMP 1)

STI Si3N4

(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 .


61

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

I. Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9 < Al/n-Si Schottky I-V >Slide Number 13Slide Number 14III. Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20Slide Number 21Slide Number 22 IV. Slide Number 24Slide Number 25Slide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33V. Slide Number 35Slide Number 36Slide Number 37Slide Number 38Slide Number 39Slide Number 40VI. Slide Number 42Slide Number 43Slide Number 44Slide Number 45Slide Number 46VII. CMP Slide Number 48Slide Number 49Slide Number 50Slide Number 51Slide Number 52Slide Number 53Slide Number 54Slide Number 55Slide Number 56Slide Number 57Slide Number 58Slide Number 59Slide Number 60Slide Number 61

vi. vii. cmpocw.sogang.ac.kr/rfile/2011/course10-spt/6금속공정... · 2011-12-29 · pt 증착...

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