Transcript 0.13-micron Industry First

Process stability control for
immersion lithography
Speaker: Chin-Yu Chang
TSMC academician
Advanced Lithography Process Department III
Nano Patterning Technology Division
R&D
P. 1
Outline
1. Immersion tool
2. Immersion material
3. Immersion process
P. 2
Scanner Defect Stability Control
UPW
inlet
lens
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

Hydrophobic or
hydrophilic
 Meniscus stability
 Less water loss
 Surface material
endurance
 Facility(UPW, Air, CO2)
 Supply stability
Optimized scan/step speed, accel
 Extreme clean material
 Optimized routing
 Filtration

P. 3
 Surface treatment
Functionality for Tool Maintenance
UPW
inlet
UPW
outlet
lens
water
wafer
Stage
Automatic self-clean
Surfactant-A
Surfactant-B
Surfactant-C
…
Liquid particle
Keep system clean always
Triggered by wafer # or time
Anion, cation,
TOC, metal…
Immersion chamber monitor
in-line chemical cleaning
Contaminant removal
Surfactant via recipe control
P. 4
SPC control, real time monitor
Trace wafer cleanness
Monitor chamber cleanness
How to Correlate Defect to System
Robust tooling for the monitor, analysis, simulation
and prediction of defect behavior
P. 5
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
P. 6
Tool Stability Control
From defectivity point of view
Trend
Concern
High scan
speed for
scanner
More defect
due to water
loss
Possible solution
1. Extra treatment before PEB
2. Resist material optimization
3. Scanner parameter tuning
CD shrinkage
More pattern
scum
1. Resist material optimization
Wafer bevel
cleanness
quality
Particle
induced
pattern failure
1. Clean bevel for incoming wafers
Defect
Inspection
Data reliability
1. Inspection tool CIP
P. 7
2. Track process optimization
2. New stage design to suppress
wafer edge defect
2. Monitor methodology CIP
Resist Formulation Tuning
P. 8
Resist Formulation Tuning
P. 9
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
P. 10
CH Developer Strategy and Challenge
Spin dry
P. 11
Freezing Process for DPT
DP process
1
Commercial freezing PR
Litho-
COT->EXP->Dev->HB
Freezing
COT->SB->Dev->HB
Litho-
COT->EXP->Dev->HB
2. Process scheme
3. Material cost comparison
US$ /gallon
Dispense volume
Cost /wafer
4. Reversal process
P. 12
Should be OK
tsmc
Top issues
1
Top-loss issue
2
Line-end loss
3
1st pattern e-beam damage
Commercial freezing PR
tsmc
Serious e-beam damage was shown
in JSR freezing material
4
1st CD-bias after freezing
5
1st/2nd PR Etching resistance
6
Risk of residual freezing
material
P. 13 7 Overlay criteria
No PR damage at line pattern, but
PR damage at island pattern.
<±2nm bias, after 2nd PR
nd
<±2nm bias, after 2 PR preparation
preparation
Different, only 1st PR is frozen.
Same, both DP PRs can be frozen.
No problem!! It will evaporate
It will cause scum defect if residue
during baking, due to boiling
is present.
point=118oC.
< 6nm
< 6nm
Implant Layer Scum Reduction
Treatment
Advantage
Good profile, CDU
No scum, poison issue
Precise implant control
Disadvantage New process
Substrate damage?
COO
P. 14
NPR
Modified PR
Good top view profile
No scum
Poor undercut profile
PR maturity
Scum, poison issue
Poor optical intensity in small trench
Chemical diffuse difficulty
DBARC iso dense bias
Immersion defect analysis – the interaction
between tool, material and process
Pattern defect
Source:
IH, stage
Lens
IH
IH
wafer
Resist process
Contamination
source: EBR, film
stack, resist
leaching
stage
stage
Contamination source:
WS, IH, resist
Clean strategy:
mechanical or chemical
clean
P. 15
Lens
Contamination source:
Leaching PAG, Particle
Clean strategy:
chemical clean
Immersion hood
Contamination source:
resist, tool, dry/wet
interface
Clean strategy:
mechanical or
chemical clean
Immersion Process- EBR Process
EBR Process
OM picture
OM wafer edge
SEM Wafer edge
PR
BARC
Conv.
New
TARC
BARC
PR
Film stack:
P. 16
Stress
Adhesion Film peeling
Swelling
Hydrophobic
/philic
SEM picture
defect
Lens Cleaning Chemical Performance
Sample 1
Sample 2
P. 17
Pre
Scanner
Cleaning 1
Cleaning 2
0.65 Amp
Mega sonic
9
641
112
34
3
645
205
247
0.9 Amp
Mega sonic
Particle remove rate vs.
mega sonic power
RR.
P. 18
99%
97%
95%
93%
91%
89%
87%
85%
0.65 0.7 0.75 0.8 0.85 0.9 0.95
ampere
1
Particle accumulation and cleaning
Immersion head
Water control apparatus
lens
Lens
1cm
out
fluid out
DI in
fluid in
fluid out
Lens
fluid in
P. 19
Background facility
Watermark defect mechanism
water drop residue
after immersion
Immersion head exposure
Water drop
PR layer
Wafer
Stage movement direction
P. 20
Wafer
Leaching from resist or contamination from air
influence the CAR(chemical amplify reaction)
Pattern collapse, defect and its solutions
BARC
Conventional:
Only consider the n,k
value
Our approach 
1. Adhesion
improvement -- Tail
structure, Porous
structure
2. Surface condition
improvement -Leaving group
structure, polarity
switchable group
P. 21
Developer
Conventional 
Surfactant rinse
Our approach 
New surfactant for collapse
and defect improvement
F
h

w
Resist
D
F=6Stcos/D(AR)2
AR: aspect ratio
: contact angle
D: space width
Conventional:
Improve resist rigidity
Our approach 
1. Change the surface
condition to decrease the
swelling and increase
surface hydrophobic.
2. Special formulation to
decrease the capillary
torque force
Pattern collapse and LWR
TMAH
DI water rinse
Spin- dry
Chemical treatment
std PR
puddle time (s)
Std
EOP (mj)
32
LWR (nm)
11.6
collapse DOM (nm)
2
collapse DOW (nm)
68
MEEF
3.84
P. 22
std. PR + CR
15
10
5
30
30.5
31
10.4
10.5
10.9
5
5
5
76
76
76
3.6
3.48
3.68
Remark
mask SPEC : CD+-3nm (1X)
CD : 60nm+-6nm