0'13micron Industry First

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Process stability control for immersion
lithography
Speaker Chin-Yu Chang TSMC academician Advanced
Lithography Process Department III Nano
Patterning Technology Division RD
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Outline
1. Immersion tool 2. Immersion material 3.
Immersion process
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Scanner Defect Stability Control
lens
UPW inlet
UPW outlet
water
wafer
Stage

• Hardware
• Clean parts
• No trash cans
• Water flow
• Soon refresh rate
• Flow direction
• Laminar flow, no dead zone
• Stage movement
• Optimized scan/step speed, accel
• Optimized routing

• Surface treatment
• Hydrophobic or hydrophilic
• Meniscus stability
• Less water loss
• Surface material endurance
• Facility(UPW, Air, CO2)
• Supply stability
• Extreme clean material
• Filtration

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Functionality for Tool Maintenance
UPW outlet
UPW inlet
lens
water
wafer
Stage
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How to Correlate Defect to System
6250-193, SPIE 2007, FJ Liang
Robust tooling for the monitor, analysis,
simulation and prediction of defect behavior
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Requirement for Track Defect Reduction

• Key module
• Coater, developer and soaking units
• Configuration
• Customized hardware (tube, nozzle, arm, cup,
  exhaust)
• Optimized unit recipe wafer flow to improve
  defect
• Innovative treatment units
• Maintenance
• Environment control
• Advanced PM skills to remain baseline
• Exploratory methodology to qualify module
  performance

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Tool Stability Control
From defectivity point of view
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Resist Formulation Tuning
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Resist Formulation Tuning
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Developer Strategy and Challenge
Spin dry
Similar contact angle between surface and sidewall
PSM/ topcoat

• High surface contact angle difference between
  surface and pattern side wall

BIM process

• Treatment
• .

Treatment process
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CH Developer Strategy and Challenge
Spin dry
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Freezing Process for DPT
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(No Transcript)
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Implant Layer Scum Reduction
NPR
Modified PR
Treatment
Good profile, CDU No scum, poison issue Precise
implant control
Good top view profile No scum
Advantage Disadvantage
New process Substrate damage? COO
Scum, poison issue Poor optical intensity in
small trench Chemical diffuse difficulty DBARC
iso dense bias
Poor undercut profile PR maturity
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Immersion defect analysis the interaction
between tool, material and process
Lens
Resist process Contamination source EBR, film
stack, resist leaching
Pattern defect Source IH, stage
IH
IH
wafer
stage
Immersion hood Contamination source resist,
tool, dry/wet interface Clean strategy
mechanical or chemical clean
Lens Contamination source Leaching PAG,
Particle Clean strategy chemical clean
stage Contamination source WS, IH, resist Clean
strategy mechanical or chemical clean
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Immersion Process- EBR Process
EBR Process
OM picture
SEM picture
defect
OM wafer edge
SEM Wafer edge
PR
BARC
Conv.
TARC
BARC
New
PR
Stress Adhesion Swelling Hydrophobic/philic
Film stack
Film peeling
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Lens Cleaning Chemical Performance
Sample 1
Sample 2
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Pre
Scanner
Cleaning 1
Cleaning 2
0.65 Amp Mega sonic
112
34
641
9
0.9 Amp Mega sonic
205
247
645
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Particle remove rate vs. mega sonic power
RR.
ampere
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Particle accumulation and cleaning
Immersion head
lens
Water control apparatus
Background facility
Lens
1cm
out
DI in
fluid in
fluid out
fluid out
Lens
fluid in
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Watermark defect mechanism
water drop residue after immersion exposure
Immersion head
Wafer
Leaching from resist or contamination from air
influence the CAR(chemical amplify reaction)
Stage movement direction
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Pattern collapse, defect and its solutions
Developer Conventional ? Surfactant rinse Our
approach ? New surfactant for collapse and
defect improvement

• BARC
• Conventional
• Only consider the n,k value
• Our approach ?
• Adhesion improvement -- Tail structure, Porous
  structure
• Surface condition improvement -- Leaving group
  structure, polarity switchable group

F
?
h
w

• Resist
• Conventional
• Improve resist rigidity
• Our approach ?
• Change the surface condition to decrease the
  swelling and increase surface hydrophobic.
• Special formulation to decrease the capillary
  torque force

D
F6Stcos?/D(AR)2 AR aspect ratio ? contact
angle D space width
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Pattern collapse and LWR
TMAH
DI water rinse
Spin- dry

Chemical treatment