kss 2010- processes for film stripping
DESCRIPTION
This Presentation was given in the Knowledge Service Seminar for TSMC head quarter in 2010TRANSCRIPT
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FSI Knowledge SERVICES™ Seminar Series 2010
Processes for Film Stripping:Implanted Photoresist and NiPt
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FSI Knowledge SERVICES™ Seminar Series 2010
Outline
• HT SPM Chemistry Theory• Film Removal Mechanism
– Ion implanted Photoresist– Post anneal residual NiPt metal
• Optimize the process in reaction chamber• Application Result
– Ion implanted Photoresist
– Post anneal residual NiPt metal
• Summary
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High Temp. boost Chemical (SPM) Reactivity
Half Cell Oxidation Reactions
HSO5- + 2H+ + 2e- HSO4
- + H2O 1.44V
HO• + H+ + e- H2O 2.80V
HSO4• + H+ + e- H2SO4 2.60V
H2O2 + 2H+ + 2e- H2O 1.78V
Mor
e ox
idiz
ing
pow
er
Main application areas are Main application areas are 1.1. FEOL polymer removal after plasma etch-ash / ion implant FEOL polymer removal after plasma etch-ash / ion implant 2.2. MOL metal selective etch for silicide formationMOL metal selective etch for silicide formation
Higher temperature
H2SO4 + H2O2
HSO4• + HO•(36 kcal/mol)
2HO•(51 kcal/mol)
H2O + ½O2
(18 kcal/mol)
H2SO5 + H2O(spontaneous)
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FSI Knowledge SERVICES™ Seminar Series 2010
Outline
• HT SPM Chemistry Theory• Film Removal Mechanism
– Ion implanted Photoresist– Post anneal residual NiPt metal
• Optimize the process in reaction chamber• Application Result
– Ion implanted Photoresist
– Post anneal residual NiPt metal
• Summary
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Implanted Photoresist
Ion implantation process has many variables- Species: B, P, As, Si, Ge, BF2
- Energy: < 1keV to > 1000keV- Dosage: 1x1011 to >1x1016 ions/cm2
- Normal incidence or angled
gate gate
cross-linkedpolymer layer
photo source: P. Gillespie et al, Semiconductor International, October, 1999
Most challenging where cross-linked resist is bonded to wafer surface especially at wafer edge, near EBR region
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Ion Implantation Causes Cross-Linking and Dehdyrogenation
Figure 4. CP-MAS 13C NMR spectra of pristine resist and crust (As 40keV 1E15cm -2)[Tsvetanova et al., ECS Trans. 25(5), 187(2009)]
CHCH2
O
nCH
CH2
O
m
CHCH2
OH
n
CHCH2
OR
m
CHCH2
O
nCH
CH2
O
nCH
CH2
O
mCH
CH2
O
m
CHCH2
OH
n
CHCH2
OH
n
CHCH2
OR
m
CHCH2
OR
m
CHCH2
OH
nCH
CH2
OR
m
CHCH2
OH
n
CHCH2
OR
m
CHCH2
OH
nCH
CH2
OH
nCH
CH2
OR
mCH
CH2
OR
m
CHCH2
OH
n
CHCH2
OH
n
CHCH2
OR
m
CHCH2
OR
m
Pristine Resist Crust
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High Activation Energy to Remove Crust
Robert Doering and Yoshio Nishi, Handbook of Semiconductor Manufacturing Technology (CRC Press, 2008).
Ashing = Gas Phase
FIGURE 7.57 Relative removal rates of standard i-line photoresist and the implanted carbonized crust layer as afunction of temperature for a oxygen plasma without ion bombardment. Activation energy (Ea) has been calculatedfrom the temperature dependence of the reaction.
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Thermodynamic ConsiderationsSpecies Electro-Chemical
Potential (eV)Reactive with
Bulk ResistReactive with
Cross-Linked Resist
O• (only exist in asher)
----- Y Y
OH• 2.80 Y Y
HSO4• 2.60 Y Y
O3 2.08 Y N
H2O2 1.78 N N
H2SO5 1.44 Y N
O2 1.23 N N
CH2
OH
H2SO5 is more effective than H2O2 because sulfuric acid can both dehydrate and dissolve short chain polymer fragments
Need radicals to attack highly cross-linked resist CH2
O
CH2HO
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Radicals attack cross-links, C-C, C-O, Si-O
CHCH2
O
nCH
CH2
O
m
CHCH2
OH
n
CHCH2
OR
m
CHCH2
O
nCH
CH2
O
nCH
CH2
O
mCH
CH2
O
m
CHCH2
OH
n
CHCH2
OH
n
CHCH2
OR
m
CHCH2
OR
m CHCH2
O
n
Si
silicon wafer
Si Si
OH OH
CHCH2
O
nCH
CH2
O
n
Si
silicon wafer
Si Si
OH OH
HSO4•or
HO•
HSO4•or
HO•
HSO4•or
HO•
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Outline
• HT SPM Chemistry Theory• Film Removal Mechanism
– Ion implanted Photoresist– Post anneal residual NiPt metal
• Optimize the process in reaction chamber• Application Result
– Ion implanted Photoresist
– Post anneal residual NiPt metal
• Summary
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pH
Vol
tage
Pot
entia
l Corrosion
Passivation
Immunity
Platinum Chemical Reaction Model
Marcel Pourbaix, Atlas of Electrochemical Equilibria, 1974
Aqua regia base :
• Pt + 4NO3- + 8H+ Pt(4+) +NO2+ 4H2O
• Pt(4+)+6Cl- + 2H+ H2PtCl6
Hydrochloric acid base :
• Pt + 2H2O2 + 4H+ Pt(4+) + 4H2O
• Pt(4+) + 6Cl- + 2H H2PtCl6
Sulfuric acid base :
Pt + H2SO4 + H2O2 Pt(OH)2++ + PtO++ + H2SO3
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Low RTP1 NixSi formation behavior
Lih J. Chen, Silicide technology for integrated circuits, IEE 2004
FIGURE 5.3 Sheet resistance versus annealing temperature measured in situ while heating Co/Si and Ni/Si films at 3◦C/s. Note that the lower resistive NiSi phase forms at considerably lower temperature than CoSi2. However, the NiSi film also degrades at lower temperature.
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Lower Anneal Temperature Address Nickel Diffusion but Creates New Problem in Strip Process (HCl attack)
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FSI Knowledge SERVICES™ Seminar Series 2010
Outline
• HT SPM Chemistry Theory• Film Removal Mechanism
– Ion implanted Photoresist– Post anneal residual NiPt metal
• Optimize the process in reaction chamber• Application Result
– Ion implanted Photoresist
– Post anneal residual NiPt metal
• Summary
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ViPR+™ (Steam-Injected SPM) Maximizes Exothermic Energy Release and Boosts Chemical Reactivity
mix with steam
0 20 40 60 80 100
0
186
enthalpyof mixtureincluding
vapor(J/g)
weight percentage H2SO4 in water
0°C
21°C38°C
66°C93°C 121°C
149°C
288°C
260°C
232°C
204°C
177°C
104°C
110°C
121°C
149°C
177°C
204°C
232°C
372
Heat of Vaporization = The Steam Advantage
0 20 40 60 80 100
0
186
enthalpyof mixtureincluding
vapor(J/g)
weight percentage H2SO4 in water
0°C
21°C38°C
66°C93°C 121°C
149°C
288°C
260°C
232°C
204°C
177°C
104°C
110°C
121°C
149°C
177°C
204°C
232°C
372
Heat of Vaporization = The Steam Advantage
1001009090808070706060weight % H2SO4
GAS
LIQUID
149°C
177°C
204°C
232°C260°C
150°C96%
enth
alpy
mix with water/H2O2
Typical Wet Bench On Wafer <150ºC
FSI ViPR™ Technology On Wafer >150ºC + high reactivity
STEAM
Typical Single Wafer On Wafer >150ºC
Steam Injection enabled by Closed Chamber & Energetic Nozzle Array
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Linear Spray Nozzle Array Enhances Film Removal(1) Multiple spray dispense for mixing with steamSpray bar chemical delivery provides better mixing with steam, higher local flow rate, thinner boundary layer and larger area processing
(2) Entire wafer surface processed at same timeSpray bar dispense provides greater and more uniform coverage than single point nozzle. Spray bar dispense provides greater and more uniform wafer temperature than point nozzle.
Single Point Nozzle Linear Nozzle Array steam
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Energized Chemical Aerosol to Boost Reactivity
Reactivity enhancement1. POU mixing to retain transient phase
chemical radical
2. N2 or Steam energized chemical aerosol to • Better wet ability• Higher collision probability /
Better mass transfer• Provide additional mechanical
force to peel off film
3. Use linear spray bar to maximize the amount of chemical mass in surface reaction.
SPM distributed evenly across wafer
N2 flow keeps fumes out
Exhaust keeps chamber pressure slightly negative, prevents escape of fumes
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FSI Knowledge SERVICES™ Seminar Series 2010
Outline
• HT SPM Chemistry Theory• Film Removal Mechanism
– Ion implanted Photoresist– Post anneal residual NiPt metal
• Optimize the process in reaction chamber• Application Result
– Ion implanted Photoresist
– Post anneal residual NiPt metal
• Summary
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Implanted Photoresist Removal By Hot SPM
dissolution ofthinner sidewallcrust by radicalreaction+ dissolution of underlying PR bydirect solvation
crust lift-off + dissolutionof crust layerby radical reaction
dissolutionof attachedcrust layerby radical reaction
ion implantationcreates cross-linked“crust” on surfaceand sidewall of PR
Physical force
Chemical force
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FSI ORION® ViPR™ Resist Strip Capability
All Wet Resist Strip
Implant Type Pre Gateand PAC
ViPR
LDDand PLAD
ViPR+
S/D
ViPR+
Implant Level Up to 1E14 up to 1E1510 keV
up to 5E1510 keV
Dispense time (sec)
15 40 100
SPM usage (liter/wafer)
0.38 1.0 2.5
Oxide loss(Å) < 0.1 ~0.2 ~0.3
Nitride loss(Å) <0.5 <1.0 ~1.5
8-chamber Thruput (wph)
200 150 115
(includes 30 second, room temperature, SC1 step)
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Low Material Loss – Oxide and Nitride
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
measurement point (concentric circles, 1=ctr, 49=edge)
ma
teri
al
los
s (
Å)
■ 80s, 4:1SPM + 30s RT SC1 - furnace silicon nitride
80s, 4:1SPM + 30s RT SC1 - furnace silicon oxide
▲ 40s, 10:1ViPR+ + 30s RT SC1 - furnace silicon nitride
∆ 40s, 10:1ViPR+ + 30s RT SC1 - furnace silicon oxide
(ERF 10297, ERF 10347, lab 2010_04_23)
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FSI Knowledge SERVICES™ Seminar Series 2010
Outline
• HT SPM Chemistry Theory• Film Removal Mechanism
– Ion implanted Photoresist– Post anneal residual NiPt metal
• Optimize the process in reaction chamber• Application Result
– Ion implanted Photoresist
– Post anneal residual NiPt metal
• Summary
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NiPt selective Etch for NiPtSi formation
PtPtPt
Si Si
Si substrateNixSiNixSi
NixSi NixSi
Si Si
Si substrate
Pt : atomic weight 195 Ni : atomic weight 58.7TiN : capping
RTP
SelectiveWet Etch
PtPtPt
HTSPM
HTSPM
Or cluster
PtPtPt
O
++
OHH
OHH
OH H
OH H
++++
Pt(OH)2++ PtO++
Pt
O
H
O
H
+ + Pt
O
+ +
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ViPR™ Process Enables Wide Range of Anneal Conditions w/o Silicide Degradation
POR (HCl)
ViPR
Silicide Attack
Presented by Stephane Zoll (ST) at KSS 2008 Seminar in Grenoble
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NiPt Selective Process Latitude
0
50
100
150
200
250
300
350
5% 5% 5% 5% 5% 5% 10% 10% 10% 10%
Pt (%)
NiP
t fil
m th
ickn
ess
ViPR 60s
ViPR 90s
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FSI Knowledge SERVICES™ Seminar Series 2010
Outline
• HT SPM Chemistry Theory• Film Removal Mechanism
– Ion implanted Photoresist– Post anneal residual NiPt metal
• Optimize the process in reaction chamber• Application Result
– Ion implanted Photoresist
– Post anneal residual NiPt metal
• Summary
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Summary
• Thermal entropy will boost the chemical reactivity for film removal and application proven
• High temperature SPM will extend the same chemical for advanced CMOS manufacturing process
• Proper modulation of both chemical / mechanical force will optimize the process