process stability control for immersion lithography
DESCRIPTION
Process stability control for immersion lithography. Speaker : Chin-Yu Chang TSMC academician Advanced Lithography Process Department III Nano Patterning Technology Division R&D. Outline. 1. Immersion tool 2. Immersion material 3. Immersion process. Hardware Clean parts No trash cans - PowerPoint PPT PresentationTRANSCRIPT
P. 1
Process stability control for
immersion lithography
Speaker: Chin-Yu Chang
TSMC academician
Advanced Lithography Process Department III
Nano Patterning Technology Division
R&D
P. 2
Outline
1. Immersion tool
2. Immersion material
3. Immersion process
P. 3
Scanner Defect Stability Control
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
lensUPW inlet
UPW outlet
wafer
Stage
water
Surface treatment Hydrophobic or hydrophilic Meniscus stability Less water loss Surface material endurance
Facility(UPW, Air, CO2) Supply stability Extreme clean material Filtration
P. 4
lensUPW inlet
UPW outlet
wafer
Stage
water
Functionality for Tool Maintenance
Surfactant-ASurfactant-BSurfactant-C…
in-line chemical cleaning
Contaminant removalSurfactant via recipe control
Anion, cation, TOC, metal…
Liquid particle
Immersion chamber monitor
SPC control, real time monitorTrace wafer cleannessMonitor chamber cleanness
Automatic self-clean
Keep system clean always Triggered by wafer # or time
P. 5
How to Correlate Defect to System
6250-193, SPIE 2007, FJ Liang
Robust tooling for the monitor, analysis, simulation and prediction of defect behavior
P. 6
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. 7
Tool Stability Control
Trend Concern Possible solution
High scan speed for scanner
More defect due to water loss
1. Extra treatment before PEB
2. Resist material optimization
3. Scanner parameter tuning
CD shrinkage More pattern scum
1. Resist material optimization
2. Track process optimization
Wafer bevel cleanness quality
Particle induced pattern failure
1. Clean bevel for incoming wafers
2. New stage design to suppress wafer edge defect
Defect Inspection
Data reliability
1. Inspection tool CIP
2. Monitor methodology CIP
From defectivity point of view
P. 8
Resist Formulation Tuning
P. 9
Resist Formulation Tuning
P. 10
Spin dry
BIM process
Treatment process
PSM/ topcoat
Similar contact angle between surface and sidewall
High surface contact angle difference between surface and pattern side wall•
Developer Strategy and Challenge
Treatment:•.
P. 11
Spin dry
CH Developer Strategy and Challenge
P. 12
Commercial freezing PR tsmc
Litho- COT->EXP->Dev->HB
Freezing COT->SB->Dev->HB
Litho- COT->EXP->Dev->HB
US$ /gallon
Dispense volume
Cost /wafer
Should be OK
DP process
4. Reversal process
3. Material cost comparison
2. Process scheme
1
Freezing Process for DPT
P. 13
Commercial freezing PR tsmc
1 Top-loss issue
2 Line-end loss
3 1st pattern e-beam damage
Serious e-beam damage was shownin JSR freezing material
No PR damage at line pattern, butPR damage at island pattern.
4 1st CD-bias after freezing <±2nm bias, after 2nd PR preparation<±2nm bias, after 2nd PRpreparation
5 1st/2nd PR Etching resistance Different, only 1st PR is frozen. Same, both DP PRs can be frozen.
6Risk of residual freezingmaterial
It will cause scum defect if residueis present.
No problem!! It will evaporateduring baking, due to boilingpoint=118oC.
7 Overlay criteria < 6nm < 6nm
Top issues
P. 14
Implant Layer Scum Reduction
NPR Treatment Modified PR
Advantage
Disadvantage
Good profile, CDUNo scum, poison issuePrecise implant control
New processSubstrate damage?COO
Good top view profileNo scum
Poor undercut profilePR maturity
Scum, poison issuePoor optical intensity in small trenchChemical diffuse difficultyDBARC iso dense bias
P. 15
wafer
IH
Lens
Immersion defect analysis – the interaction between tool, material and process
LensContamination source:Leaching PAG, ParticleClean strategy: chemical clean
Immersion hoodContamination source:resist, tool, dry/wet interfaceClean strategy: mechanical or chemical clean
stageContamination source:WS, IH, resistClean strategy: mechanical or chemical clean
stage
IH
Pattern defectSource:IH, stage
Resist process Contamination source: EBR, film stack, resist leaching
P. 16
OM wafer edge
TARC BARC
PR
Conv.
New
SEM Wafer edge
BARC
PR
defect
Immersion Process- EBR ProcessOM picture SEM pictureEBR Process
Film stack:
Film peeling StressAdhesionSwellingHydrophobic/philic
P. 17
Sample 2
Lens Cleaning Chemical Performance Sample 1
P. 18
Pre Scanner
0.65 AmpMega sonic
0.9 AmpMega sonic
Cleaning 1 Cleaning 2
112
205
641
645
9
3
34
247
85%87%89%91%93%95%97%99%
0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
Particle remove rate vs. mega sonic power
ampere
RR.
P. 19
Particle accumulation and cleaning
Lens
fluid in fluid out fluid out
1cmDI in out
lens Water control apparatus Background facility
Immersion head
Lens
fluid in
P. 20
Wafer
Immersion head
water drop residue after immersion exposure
Leaching from resist or contamination from air influence the CAR(chemical amplify reaction) Stage movement direction
Water drop
Wafer
PR layer
Watermark defect mechanism
P. 21
h
w
D
F
Pattern collapse, defect and its solutions
ResistConventional: 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
DeveloperConventional Surfactant rinse
Our approach New surfactant for collapse and defect improvement
F=6Stcos/D(AR)2
AR: aspect ratio
: contact angle
D: space width
BARCConventional: 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. 22
std PR Remarkpuddle time (s) Std 15 10 5EOP (mj) 32 30 30.5 31LWR (nm) 11.6 10.4 10.5 10.9collapse DOM (nm) 2 5 5 5 mask SPEC : CD+-3nm (1X)collapse DOW (nm) 68 76 76 76 CD : 60nm+-6nmMEEF 3.84 3.6 3.48 3.68
std. PR + CR
TMAH DI water rinse Spin- dry
Chemical treatment
Pattern collapse and LWR