W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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I.
II. -
III.
IV.
V.
VI. VII. CMP
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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I.
1): contact, interconnection, connection to outside
2) IC : yield, reliability
3) system (1) (2) (3)
1.
2. 1)
(1) : , , ,
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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, ,
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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.
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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1. 1) Schottky 2) Ohmic : tunneling
2. 1) n
II. -
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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 >
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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3.
1) N
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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%
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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(2) filament , RF e-beam , flash
(3) filament
< >
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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heater : W, Ta, Mo, Pt( ) heater
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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tight beam diffuse beam
pure metal refractory metal alloy x-ray
(6) alloy wire feeding , e-beam 20%
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2)
(1)
chamber step coverage (Ar 1-10 mtorr) cleaning
(2) : ,
(DC )
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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:
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2)
(1) .
(2) .
(3) .
(4) .
(5) 510-6 torr .
(6) .
(7) .
(8) .
(9) .
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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3)
(1) : , , , , ,
grain, roughness,
(2) : stylus
(3) : 4-point probe
4) Na+ : HTB C-V
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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IV.
1.
1) grain size
2) Al2O3 : T>250, 10-810-5 torr P
TRG
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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 +=+
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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 - -
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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4. Coverage 1) shadowing : slope, geometric, self shadowing
shadow :
Dh)XL
21( o=
})X(0.5LD/{arctan o>
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2) shadowing
deposition system
biaxial planetary source source-substrate
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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,
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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V.
1. Double metal
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2. 1)
2) : (, , ) (, ) (, )
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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3) (1) : , 5000 (2) : , , m (1 Al 1.65 Al2O3) 4)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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(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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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VI.
1. - 1) eutectic point 577 1.6% 2) 350 0.1% 3) Al spike
alignment packaging (111) (110) 36
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2. 1) : bipolar
MOS 2) : Na+
barrier (Si3N4, Al2O3, PSG)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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:
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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=
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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(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 (
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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VII. CMP
1. 1)
2) 1980 , 3) , MOSFET
4)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2. CMP 1) 2)
3) () ()
4) nm
(planarization) (Damascene)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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3. CMP 1)
: , : , : : :
polishing pad
slurry dispenser
platen
chuck
wafer
spindle
CMP
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2)
: um
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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3) : + : pH: : SiO2, Al2O3, CeO2 CMP : + Al2O3 CMP
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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4) CMP : , , , : , , , , pore ,
5) CMP
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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= =
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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5. CMP 1)
STI Si3N4
(stopping layer)
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2) CMP: (contact) (via) (plug) CMP: CMP
7
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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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
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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2) SiO2 (k > 2.7):
(k < 2.7): tetramethoxysilane(TMOS) tetraethoxysilane(TEOS) -
: (air gap)
3) , / , , , CMP , , , , , ,
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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7. 1)
: , ,
2) : (1.7ucm), electromigration, , ,
: , , ,
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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3) : : via filling
4) : via trench
. .
. (adhesion) (barrier) . .
. CMP .
W. Y. Choi, B.-G. Park, and J. D. Lee, Fundamentals of Silicon IC Processes
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. (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