From ArF Immersion to EUV Lithography Luc Van den hove Vice President IMEC
Outline Introduction 193nm immersion lithography EUV lithography Global collaboration Conclusions
Lithography is enabling 1000 ITRS Technology Trends MPU Gate Length Gate Length (nm) 100 10 2-year Node Cycle 3-year Node Cycle 1 1995 2000 2005 2010 2015 2020 Year Source: 2003 ITRS - Exec. Summary
Rayleigh equation Wave length scaling Lord Rayleigh resolution = k1. λ NA 193nm 157nm
157nm Challenges CaF 2 lens material Catadioptric lens design Fluorinated resist materials Mask technology Modified SiO 2 Surface contamination Pellicle: none / soft / hard transmission radiation hardness reticle heating Purging N 2 fill
Outline Introduction 193nm immersion lithography EUV lithography Global collaboration Status, Challenges, Outlook Conclusions
Rayleigh equation Lord Rayleigh resolution = k1. λ NA NA scaling
Immersion Lithography Improvements in resolution Snell s law : NA = η = 0 sin θ 0 = η f sin θ f η r sin θ r η glass n glass η 0 η f liquid η r
Immersion Lithography Improvements in resolution Snell s law : NA = η = 0 sin θ 0 = η f sin θ f η r sin θ r η glass n glass η 0 dry η f liquid η r
Immersion Litho Extremely short introduction time
Immersion demonstration in record time March 2002: Key note presentation @ SPIE Santa Clara Burn Lin (TSMC): First suggestion to consider immersion lithography 2002 2003 2004 Mirror Fluid Inlet Vacuum Pump Fluid Replenishing Hole Last Lens Element Tank Cover Wafer Fluid Thermal Control Filter Fluid Outlet Mirror Drain
Immersion demonstration in record time March 2002: Key note presentation @ SPIE Santa Clara Burn Lin (TSMC): First suggestion to consider immersion lithography 2002 2003 2004 October / November 2003: ASML and IMEC demonstrate feasibility on 0.75NA immersion prototype scanner First immersion scanning image on Oct 7, 2003 DOF @ 8% EL 1200 1000 800 600 400 200 0 180 270 160 270 200 320 160 270 160 270 0.92-0.72 + Att PSM 0.89-0.65 + Att PSM 0.89-0.65 + BIN 0.89-0.65 + BIN DRY WET 0.89-0.45 + BIN > 50% DOF gain demonstration
Immersion demonstration in record time March 2002: Key note presentation @ SPIE Santa Clara Burn Lin (TSMC): First suggestion to consider immersion lithography 2002 2003 2004 October / November 2003: ASML and IMEC demonstrate feasibility on 0.75NA immersion prototype scanner January 2004: Sematech Lithography Forum Los Angeles World momentum shifts entirely from 157nm to immersion lithography
Immersion demonstration in record time March 2002: Key note presentation @ SPIE Santa Clara Burn Lin (TSMC): First suggestion to consider immersion lithography 2002 2003 2004 October / November 2003: ASML and IMEC demonstrate feasibility on 0.75NA immersion prototype scanner January 2004: Sematech Lithography Forum Los Angeles World momentum shifts entirely from 157nm to immersion lithography 193nm immersion 157nm
Immersion demonstration in record time March 2002: Key note presentation @ SPIE Santa Clara Burn Lin (TSMC): First suggestion to consider immersion lithography 2002 2003 2004 October / November 2003: ASML and IMEC demonstrate feasibility on 0.75NA immersion prototype scanner January 2004: Sematech Lithography Forum Los Angeles World momentum shifts entirely from 157nm to immersion lithography End 2004: multiple 2 nd generation 0.85 NA immersion scanners have been shipped (TSMC, IMEC)
Immersion Lithography A few challenges Process interactions Defectivity Polarization effects -1 +1 Lens dimensions
Immersion Lithography A few challenges Process interactions Defectivity Polarization effects -1 +1 Lens dimensions
Process Interactions Interaction of resist/top coat with water
Process interactions Some topcoats reveal an intrafield CD fingerprint similar to the soak simulations Soak simulation CD fingerprint
Process interactions CD soak fingerprint using new developer soluble topcoats is significant reduced compared to TSP3A (but still visible) New developer soluble topcoats TSP3A TILC019 TCX007
Immersion Lithography A few challenges Process interactions Defectivity Polarization effects -1 +1 Lens dimensions
Immersion defectivity A spherical air bubble casts a shadow
Bubble Defects Simulated (2-beam imaging) aerial image of 500nm bubble defect on 100nm L/S pattern
Bubble improvement (/1250i) Non-optimized conditions After optimization
Immersion specific defects Scanner contributions Bubbles (related to shower head design, wafer chuck design, ) Defects (related to water residues, related to chuck/head design, ) Resist/process contributions Resist leaching (resist conposition, use of top coat, ) Hydrophobicity (material contact angle, material response to water droplets, ) Water quality (particles, bacteria, TOC, ) α = 70 α = 105
Immersion Lithography A few challenges Process interactions Defectivity Polarization effects -1 +1 Lens dimensions
Polarization at high NA X-polarized (TM) NA=0.6 Y-polarized (TE) -1 +1-1 +1 Angle of incidence in resist Image contrast 70% 20 Image contrast 92% 1 0.9 0.8 0.7 0.6 In tensity 0.5 0.4 0.3 0.2 0.1 0-11 -108-101 -94-87 4-80 -73 6-66 -59-52 -46-39 -32 2-25 -18 4-11 -46 2 9.2 16 23 293643 50 6 57 64 4 7178 2 85 92 98 105112 Medium NA NA (0.6) (0.6) in in resist resist (n=1.7) (n=1.7)
Polarization at high NA X-polarized (TM) NA=0.85 Y-polarized (TE) -1 +1-1 +1 Angle of incidence in resist Image contrast 49% 30 Image contrast 92% 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 High High NA NA (0.85) (0.85) in in resist resist (n=1.7) (n=1.7) -81-76 -72-68 -64-60 -56-52 -48-44 -40-36 -32-28 -24-20 -16-12 -8.1-40 4.03 8.05 12.1 16.1 20.1 24.2 28.2 32.2 36.2 40.3 44.3 48.3 52.3 56.4 60.4 64.4 68.4 72.5 76.5 80.5
Polarization at high NA X-polarized (TM) NA=1.3 Y-polarized (TE) -1 +1-1 +1 Angle of incidence in resist Image contrast -8% 50 Image contrast 59% 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 Very Very High High NA NA (1.3 (1.3 immersion) in in resist resist (n=1.7) (n=1.7) -52-49 -47-44 -42-39 -36-34 -31-29 -26-23 -21-18 -16-13 -10-7.8-5.2-2.6 0 2.6 5.2 7.8 10.4 13 15.6 18.2 20.8 23.4 26 28.6 31.2 33.8 36.4 39 41.6 44.2 46.8 49.4 52
Contrast enhancement with polarization SRAM, half pitch 55 nm, pitch 110 nm, 6% att PSM, dipole Y Un-polarized 0.93 NA dry BE+6.6% BE+3.3% BE BE-3.3% BE-6.6% BE+15.4% BE+10.3% BE+5.1% BE BE-5.1% BE-10.2% BE-15.4% Polarized Design adjustments
Immersion Lithography A few challenges Process interactions Defectivity Polarization effects -1 +1 Lens dimensions
Hyper NA: lens cost
Hyper NA: lens cost 193nm lens 2003 G-line lens 1975 >1000 mm >300 mm
Cost innovations in Optics for hyper NA 12 10 Expected according geometrical scaling dioptric Released or expected dioptric New catadioptric design Air Water Lens complexity 8 6 4 2 0 0.63 0.75 0.85 0.93 1 0.93 i 1.1 i 1.2 i 1.3 i n air NA 1.43 i n water
Outline Introduction 193nm immersion lithography EUV lithography Global collaboration Status, Challenges, Outlook Conclusions