Laser Spike Annealing for FinFETs...FinFETs Jeff Hebb, Ph.D. Julyy, 11, 2013 1 NVVAVS West Coast...
Transcript of Laser Spike Annealing for FinFETs...FinFETs Jeff Hebb, Ph.D. Julyy, 11, 2013 1 NVVAVS West Coast...
Laser Spike Annealing for FinFETs
Jeff Hebb, Ph.D.July 11, 2013y ,
1 NVVAVS West Coast JunctionTechnology Group Meeting July 11, 20131
Outline
• LSA Overview and Key Featuresy• FinFET Process Flow• LSA Applications for FinFETLSA Applications for FinFET• Summary
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LSA Overviewvs
CO2 Laser Temperature Power Control 2
(10.6μm) ConversionControl Algorithm
Hot Chuck
p-polarizedReflective
OpticsEmission Detector
Laser Beam
Vs
Dwell ti =
wHot Chuck
Scanning Stage
Silicon
time vx
Key Attributes• CO2 Laser: λ ~ 10umWithin die
Within-wafer • Temperature feedback
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CO2 Laser: λ 10um• P-polarized, brewster angle
Within-dieUniformity
&Wafer-to-wafer
• Temperature feedback control
Pattern Effects: Thin Film Interference
• Short λ • Long λLSAFLA & DL
Short λ• Normalincidence
• Long λ• Brewster angle• p-polarization
Diode Laser(λ=0.8um)
FLA/RTP
Diode Laser(λ=0.8um)
FLA/RTP
60
80
100
y(%
)
Bare Si wafer340 nm oxide on Si+10% oxide thickness-10% oxide thickness120 nm poly on oxide+10% poly thickness-10% poly thickness
LSA
θCO2
60
80
100
y(%
)
Bare Si wafer340 nm oxid
60
80
100
y(%
)
Bare Si wafer340 nm oxide on Si+10% oxide thickness
e on Si+10% oxide thickness-10% oxide thickness120 nm poly on oxide+10% poly thickness
-10% oxide thickness120 nm poly on oxide+10% poly thickness-10% poly thickness
LSA
θCO2
θCO2
20
40
Ref
lect
ivity
LSACO2 (λ =10.6um)P-polarizedBrewsters Angle
20
40
Ref
lect
ivity
20
40
Ref
lect
ivity
LSACO2 (λ =10.6um)P-polarizedBrewsters Angle
9.0 9.5 10.0 10.5 11.0 11.5 12.0Wavelength (μm)
09.0 9.5 10.0 10.5 11.0 11.5 12.0
Wavelength (μm)
09.0 9.5 10.0 10.5 11.0 11.5 12.0
Wavelength (μm)
0
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• Pattern effects caused by thin film interference variations severe at short λ• Long λ insensitive to device film variations
Pattern Effects: Scattering and Light Trapping
High aspect ratio fins Laser 0.2
0.25
s 10.6um Diode
0.1
0.15
0.2
mal
ized
Cou
nts
0.8um
>100X
DiodeLaser
LSA
Total Integrated Scattering: 0
0.05
0.01 0.1 1 10 100
Nor
m• Height is still << 10.6um, so:
• Scattering/light trapping is
24⎟⎠⎞
⎜⎝⎛≈=
λπσ
i
s
RPPTIS
Scattering (%)
g g pp gminimal for LSA
• No shadowing effectsσ is rms surface roughness
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LSA pattern effect advantage extends to FinFETs
LSA with Full Wafer Ambient Control
Process gasPre-heat Laser
Dual-beam LSA201
CO2Micro-chamber
Water-cooled plate
Process gas
Non-contact gasbearing
O2 sampling port
Hot chuck
• Patented microchamber approach allows ambient control in a scanning system
• Enables applications which involve interface control and film • Enables applications which involve interface control and film modification, which will become more critical with smaller devices and new materials
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Hypothetical FinFET Process Flow
Fin/STI formation
Implant N-ext
Fin formation*
Implant N-extImplant P-extSpike RTP (low temp)LSA
Extension
SpacerNMOS epi (in-situ doped Si:C)PMOS epi (in situ doped SiGe)LSA
Source/Drain
LSA
Interfacial layerHigh KPost dep anneal (LSA)
GateStackPost dep anneal (LSA)
Metal gate
Silicide metal depLSA
Stack
Silicide
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LSA
Backend
Silicide
* FinFET Renditions from Threshold Sytems (2103)
LSA Applications for FinFETSilicide contact
Hi k
pp
Extensionanneal
Hi-kanneal LSA Applications
1. Extension annealanneal 2. S/D activation anneal
3. HK anneal
4 R ti ti4. Re-activation
5. Silicide formation
S/D activation
• There are multiple LSA applications for FinFET
8 NVVAVS West Coast JunctionTechnology Group Meeting July 11, 20138* FinFET rendition from V. Moroz (2013)
• There are multiple LSA applications for FinFET
LSA for Extension Anneal
as implanted 600C/60s 1050C RTA Twin
R. Duffy, APL (2007)
Twindefects
A 5k V 1 15 d i l t @ 45dAs 5keV 1e15 quad implant @ 45deg
• LSA offers higher activation and a different time regime for SPE
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LSA offers higher activation and a different time regime for SPE to potentially improve defectivity
LSA for S/D AnnealImproved process results:(ext doping + epi + LSA)
NFET
LSA PFET
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T. Yamashita et al (IBM), VLSI 2011)
LSA for NMOS Epitaxial eSiCpXRD of epi film Total series resistance of NMOS
Spike RTA: Csub CintActivation increases with LSA
sub intLSA: Cint Csub !!
• For epitaxial eSiC, LSA increases the concentration of substitutional C, enhancing NMOS mobility while simulataneously increasing Phosphorous
11 NVVAVS West Coast JunctionTechnology Group Meeting July 11, 2013P. Grudowski et al. (Freescale), IEEE SOI (2007)
enhancing NMOS mobility, while simulataneously increasing Phosphorous activation
LSA For High-k Post-Depostion Anneal
Advantages of LSA for HK Anneal
g
RTP
HfO2 Hf0.5Zr0.5O2
Advantages of LSA for HK Anneal
• Lower gate leakage• Smoother film
RTP
Ig = 2.1e-2
• Higher k value due to higher concentration of tetragonal phase
LSA
• Lower thermal budget can give thinner interfacial layer
• Fast ramp-down avoids dopant de-
Ig = 7.2e-8
• Fast ramp-down avoids dopant de-activation
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*Sources: Triyoso et al., Appl. Phys. Letters (2008)Gilmer et al., ESSDERC (2006)
High k Anneal: LSA vs. FLA Cooling Comparison
Flash LampLaser Simulated Temperature Profiles
1200
1400
o C)
FLA
LSATdwell=10ms
Backside floatBackside chucked
800
1000
Tem
pera
ture
(o
FLA cool-down limited by radiation loss
• LSA ramps down quickly by cooling by 3D conduction
• FLA cools slowly by radiativecooling to the
400
600
0 1 2 3 4 5 6 7 8 9 10
3D conduction to the bulk Si
cooling to the ambient (1D)
• Device performance is improved with LSA compared to Flash Anneal because fast
Time (s)
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ramp-down avoids dopant de-activation• RTP will also have slow ramp-down and possible de-activation
Intel Study on Dopant De-activation during Flash Annealy g
Intelslide
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Advantages of LSA for Advanced Silicidesg
• Within-die uniformityDiode Laser (0.8um)
ΔT > 100oCLSA (10.6um)ΔT ~ 10oC
• Pattern effects much higher on diode laser system due to interference effects and higher silicideeffects and higher silicidereflectivity
• TemperatureClosed loop control:
Advanced Silicide Device WaferTemperature measurement and control
f
+/- 10C
• Real time measurement of temperature of wafer surface and closed loop feedback
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feedback
Laser Annealing for Advanced Silicidesg
Advantages of LSA for Ti silicide⎟⎟⎠
⎞⎜⎜⎝
⎛∝
D
Bc N
φρ exp
Gate Contact Source/Drain Contact• Higher temperature than RTA
lower contact resistance• Minimal interdiffusion of gate stack • Minimal interdiffusion of gate stack
layers• Process control
• Minimal pattern effects• Closed loop temperature controlTi
Chipworks Xray of I t l 22 Fi FET
• Becomes critical for Ti silicidewhere process window is smaller than Ni silicide
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Source: V. Moroz (Synopsys), 2013
Intel 22nm FinFET
Process Window: Ni vs. Ti SilicideProcess Window: Ni vs. Ti Silicide
Ni silicide transition Ti silicide transition (Ti on SiGe)
20
25
30
Ni silicide transition
80
100
Ti silicide transition (Ti on SiGe)
10
15
20
Rs
(ohm
/sq)
40
60
Rs
1000-1100C850-950C700-850C
0
5
0
20
Temperature Temperature
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• For Ti silicide, process window becomes narrower benefits of tighter temperature distribution from LSA becomes more critical.
Summaryy• Long-wavelength LSA retains fundamental advantages
(minimal pattern effects and closed loop control) for ( p p )FinFETs
• LSA applications summary:• Extension anneal: Higher activation, potential for reduced
defects• S/D anneal: Higher activation, improved NMOS strain• High k anneal: Lower leakage, no de-activation• Ti Silicide: Low thermal budget, tight process control
• Expect millisecond annealing to play an increasing role• Expect millisecond annealing to play an increasing role in IC manufacturing as devices are scaled to 10nm and below
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