6금속공정_20111229151922 al, cu, au coreano
TRANSCRIPT
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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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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