Lithography options for the 32nm half pitch node imec 2006 1
Lithography options for the 32nm half pitch node Luc Van den hove and Kurt Ronse
ITRS roadmap:32 nm half pitch requirement Product Half-Pitch, Gate-Length (nm) Fig 7&8 Simplified Option 1 2005 ITRS Product Technology Trends - Half-Pitch, Gate-Length 1000.0 100.0 10.0 Before 1998.71X/3YR After 1998.71X/2YR Flash Poly.71X/2YR Gate Length.71X/3YR MPU M1.71X/2.5YR MPU & DRAM M1 & Flash Poly.71X/3YR GLpr IS = 1.6818 x GLph DRAM M1 1/2 Pitch MPU M1 1/2 Pitch (2.5-year cycle) Flash Poly 1/2 Pitch MPU Gate Length - Printed MPUGate Length - Physical 1.0 1995 2000 2005 2010 2015 2020 Year of Production imec 2006 3
32nm half pitch options resolution = k1. λ NA NA k 1 λ Technical challenges: ArF Immersion 1.65 NA (k 1 =0.275) Single exposure ArF Immersion with double patterning 1.35 1.40 NA (k 1 =0.20) EUVL 0.25 NA (k 1 =0.6) Single exposure Lens complexity New liquid (n f >1.8) New optical material (n>1.9) Overlay requirement Process integration Source power Optics lifetime Resist infrastructure Mask infrastructure imec 2006 4
Outline Introduction 193 nm immersion lithography EUV Lithography Double patterning Conclusions imec 2006 5
193nm immersion lithography from RESEARCH IDEA to DEVELOPMENT in WORLD RECORD TIME imec 2006 6
193nm immersion lithography from DEVELOPMENT to MANUFACTURING??? DEFECTIVITY Is immersion ready? imec 2006 7
Status 193nm immersion lithography Defectivity Air bubbles Water marks and drying stains Resist / TC water interaction Particles imec 2006 8
Status 193nm immersion lithography Defectivity Air bubbles : no longer an issue Early config. Latest XT:1250i config. 24 bubbles 0 bubbles imec 2006 9
Status 193nm immersion lithography Defectivity Water marks and drying stains Receding contact angle approaching 0 Depends on material hydrophobicity Depends on scan speed (500mm/s) imec 2006 10
Status 193nm immersion lithography Defectivity Water marks and drying stains Number of Water Droplets Receding Contact Angle imec 2006 11
Status 193nm immersion lithography Defectivity Resist / TC water interaction Leaching of resist components in the water Water uptake by resist / TC imec 2006 12
Status 193nm immersion lithography Defectivity Resist / TC water interaction Leaching status Method in place for dynamic leaching measurements leaching (mol/cm 2 ) 2.5E-11 2.0E-11 1.5E-11 1.0E-11 5.0E-12 0.0E+00 PAR-817 0 2 4 6 8 10 time (s) 1.E-11 9.E-12 8.E-12 7.E-12 6.E-12 5.E-12 4.E-12 3.E-12 2.E-12 1.E-12 0.E+00 leaching rate (mol/cm 2.s) Amount of leaching during first 1-2 seconds is key (for a high throughput immersion scanner) imec 2006 13
Status 193nm immersion lithography Defectivity Resist / TC water interaction Leaching status Method in place for dynamic leaching measurements Top coats very efficient in preventing leaching (~100 x less) 2.5E-11 2.5E-13 leaching (mol/cm 2 ) 2.0E-11 1.5E-11 1.0E-11 5.0E-12 PAR-817 leaching (mol/cm 2 ) 2.0E-13 1.5E-13 1.0E-13 5.0E-14 PAR-817 + TCX-007 0.0E+00 0 2 4 6 8 10 time (s) 0.0E+00 0 2 4 6 8 10 time (s) Leaching currently prime reason to use top coat Recent immersion specific resists much lower leaching (factor 4) (5.10-12 mol/cm plateau) imec 2006 14
Status 193nm immersion lithography Defectivity Particles Wafer edge film peeling Edge bead engineering! Particle transport from chuck onto wafer Resist Wafer Shower Head Stage imec 2006 15
Status 193nm immersion lithography Defectivity Particles Wafer edge film peeling Edge bead engineering! BARC BARC BARC BARC Resist Resist Resist Resist Before exposure After exposure Before develop SEM after develop imec 2006 16
Breakthroughs by strong partnership Defect reduction trend (daily monitor) 2005 2006 Immersion defects Count (# defects/wafer) 500 450 400 350 300 250 200 150 100 50 0 1 2 3 4 5 1 2 3 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 1 2 3 1 2 3 1 2 1 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 9-9- 9-9- 9-23-23-23-29-29-29-29-29-6- 6-6- 6-6- 13-13- 13-13- 13-23-23-23-24-24-24-25-25-25-26-26-27-30-30-30-31-31-31-1- 1-1- 2-2- 2-3- 3-3- 5-5- 5-6- 6-6- 7-7- 7-8- 8-8- 9-9- 9-10-10-10- Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov NovDecDecDecDecDecDecDecDecDecDecJanJanJanJanJanJanJanJanJanJanJanJanJanJanJanJanJanJanFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFebFeb date Spectacular progress over the past 12 months imec 2006 17
193nm immersion lithography Polarization Litho friendly 6T SRAM design SRAM array after spacer etch 0.186μm 2 cell size 32nm node ASML XT:1250i 0.85 NA SRAM array after spacer etch Fin hp : 62nm (0.273 k 1 ) Poly hp : 75nm (0.330 k 1 ) imec 2006 18
193nm immersion lithography Polarization Litho friendly 6T SRAM design Un-polarized ASML XT:1400 0.93 NA Dipole Y illumination 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 Fin hp 55nm (0.265 k 1 ) 22nm node imec 2006 19
193nm immersion lithography Hyper NA 193i 50nm 50nm k k 1 =0.31 1 =0.31 ASML XT1700i NA=1.2 1.2NA, 1.2NA, σ=0.74/0.94, σ=0.74/0.94, annular annular 400nm -150nm NF +150nm 400nm DoF -210nm -210nm -150nm -90nm DoF -90nm NF +90nm +90nm +150nm +210nm +210nm 45nm 45nm k k 1 =0.28 1 =0.28 1.2NA, 1.2NA, σ=0.82/0.97, σ=0.82/0.97, C-Quad-30 C-Quad-30 500nm 500nm DoF DoF -300nm -300nm -240nm -240nm -120nm -120nm NF NF +60nm +60nm +120nm +120nm +210nm +210nm 42nm 42nm k k 1 =0.26 1 =0.26 1.2NA, 1.2NA, σ=0.89/0.98, σ=0.89/0.98, Dipole Dipole X-35 X-35 950nm 950nm DoF DoF -500nm -500nm -300nm -300nm -180nm -180nm NF NF +180nm +180nm +300nm +300nm +450nm +450nm imec 2006 20
193nm immersion lithography Hyper NA 193i 41nm, approaching 0.25k 1 1 ASML XT:1700i 1.2 NA P86 P86 k 1 0.267 1 0.267 P84 P84 k 1 0.261 1 0.261 P82 P82 k 1 0.254 1 0.254 43nm 43nm dense dense 42nm 42nm dense dense 41nm 41nm dense dense 1.2NA, 1.2NA, Y-pol, Y-pol, dipole dipole X 35 35 s=0.98-0.89 s=0.98-0.89 CPL CPL chromeless chromeless lines lines 42nm 42nm barc, barc, 120nm 120nm resist, resist, topcoat topcoat 41nm dense imec 2006 21
193nm immersion lithography Ultimate limits Half Pitch (nm) k 1 as function of NA and half pitch (λ=193nm) 65 60 k 1 < 0.4 55 50 k 1 < 0.27 45 45nm 40 35 30 32nm 25 20 15 0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65 NA 32nm half pitch limit requires 1.65 NA imec 2006 22
193nm immersion lithography Liquids beyond water? High index liquid testing on ASML Immersion Interference Printer Pol Excimer laser Waveplate D PC BS Prism WDS HIL stays between prism and wafer during stage motion Stages Wafer imec 2006 23
193nm immersion lithography Outlook high index liquids Lithographic results 2 nd generation fluids (n=1.65) :36nm HP Water (n=1.44) : 14.6 % EL HIL (n=1.65) : 18 % EL 50 50 Line CD (nm) 45 40 35 30 Line CD 45 40 35 30 25 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 Exposure dose (uncalibrated) 25 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 Exposure dose (uncalibrated) imec 2006 24
2 nd generation HI liquids Contact angle measurements Much lower surface tension : containment? H 2 0 HI Liquid imec 2006 25
2 nd generation HI liquids Interaction HI liquid with resist (defect formation?) Purpose: apply droplets of the liquid on either an inert substrate or resist surface in a controlled way Analyse what is left after drying (profilometry) 100 µm imec 2006 26
NA=1.65 requirements application High n f Resist development imaging characterization, defectivity High n f Fluid characterization (n f >1.9) Defectvity: Leaching & drying stains Can we use HI fluids? immersion system lens Fluid recycling system Radiation & contamination evaluation Fluid containment Scanning tests & IH evaluation Optical system HRI glass evaluation (n f > 1.8) Can we make the system? Can we make the lens? TIMING is most critical imec 2006 27
193nm immersion lithography Ultimate limits Half Pitch (nm) k 1 as function of NA and half pitch (λ=193nm) 65 60 k 1 < 0.4 55 50 k 1 < 0.27 45 40 35 30 25 20 15 0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65 45nm 32nm NA imec 2006 28
Outline Introduction 193 nm immersion lithography EUV Lithography Double patterning Conclusions imec 2006 29
EUV Lithography Critical challenges 2005 International Symposium on EUVL Critical Technical Issues for EUV Lithography Top 3 Critical Issues 2004 Rank 1. Resist resolution, sensitivity and LER 3 2. Collector lifetime 2 3. Availability of defect free masks 1 4. Source power Remaining Critical Issues Reticle protection during storage, handling and use Projection and illuminator optics quality and lifetime *** Significant concern: Timing and cost / business case for EUVL development. imec 2006 30
Experimental : Interference Lithography Paul Scherrer Institute (PSI), Switzerland Mask: beamline Exposure chamber P = wafer P 2 mask imec 2006 31
30 nm 32.5 nm 40 nm EUV Resist progress 2004 2005 2006 20 mj/cm 2 7.5 mj/cm 2 12.4 mj/cm 2 imec 2006 32
AD-tool imaging results : 40nm scanning H-lines/spaces through focus 40nm L/S -100 nm -50 nm near focus +50 nm +100 nm >200 nm DOF Resist: MET-2D ~18 mj/cm2 NA=0.25, σ=0.5 no process optimization yet imec 2006 33
AD-Tool imaging results : 40nm scanning H-lines/spaces through slit Full slit coverage 40nm L/S (22-May- 06) -10.6 mm -6.36 mm 0.0 mm 6.36 mm 10.6 mm Resist: MET-2D ~18 mj/cm2 NA=0.25, σ=0.5 no process optimization yet imec 2006 34
AD imaging results: 55 nm CH Dense (aligned) Dense (staggered) Iso (aligned) Iso (staggered) All at same conditions: - NA/Illumination/focus/dose -Binary mask - No OPC applied! 55 nm CH Resist: MET-2D no process optimization ~40 mj/cm 2 NA=0.25, σ=0.5 imec 2006 35
Double patterning Outlook k 1 as function of NA and half pitch (λ=193nm) Half Pitch (nm) 65 60 55 50 45 40 35 30 25 20 15 k 1 < 0.27 193 nm 0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65 NA k 1 = 0.4 k 1 = 0.27 45nm 32nm 22nm EUVL 0.2 20 0.25 0.30 0.35 imec 2006 36
Outline Introduction 193 nm immersion lithography EUV Lithography Double patterning Conclusions imec 2006 37
Double patterning (2x litho + 2x etch) Possible integration flow Resist Nitride HM Si Int. Exposure 1 & development Transfer to hardmask ASML XT:1400 0.93 NA 40 nm L&S etched in oxide hard mask on poly-si k 1 =0.19 Int. Exposure 2 & development Transfer to hardmask 1nm alignment error -> 1nm CD change imec 2006 38
Design Split exercises NAND FLASH Double Line for Poly TARGET Cr - ImA SPLIT + OPC PROCESS CHECK Annular 0.8/0.4 Unpolarized 1.35NA min pitch 128nm k1=0.44 min pitch 64nm k1=0.22 intuitive split Cr - ImB imec 2006 39
Design Split exercises NAND FLASH Double Trench for Poly TARGET Cr - ImA SPLIT + OPC PROCESS CHECK Annular 0.85/0.55 Unpolarized 1.35NA min pitch 128nm k1=0.44 min pitch 64nm k1=0.22 Cr - ImB imec 2006 40
Design Split exercises Logic NOR Double Line for Poly TARGET SPLIT + OPC PROCESS CHECK Annular 0.8/0.4 Cr - ImA Unpolarized 1.35NA min pitch 90nm k1=0.31 Cr - ImB imec 2006 41
Design Split exercises Logic NOR Double Trench for Poly TARGET SPLIT + OPC PROCESS CHECK Annular 0.8/0.4 Cr - ImA Unpolarized 1.35NA min pitch 90nm k1=0.31 Cr - ImB imec 2006 42
Double Line for Poly DP k1=0.14 /1250i 193nm 0.85NA Dipole DP 32nm 1:1 resist 48.7nm at 130nm pitch LER(3s) 3.1nm HM etch&strip 38nm at 130nm pitch LER(3s) 5nm resist+hm 48.7nm at 130nm pitch LER(3s) 3.1nm Poly 32nm at 65nm pitch Resist Litho Etch/strip Litho Etch/strip BARC HM Poly Si Si imec 2006 43
Double patterning Outlook k 1 as function of NA and half pitch (λ=193nm) Half Pitch (nm) 65 60 55 50 45 40 35 30 25 20 15 193 nm k 1 = 0.4 k 1 = 0.27 k 1 = 0.20 0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65 NA Double patterning 45nm 32nm 22nm EUVL 0.2 20 0.25 0.30 0.35 imec 2006 44
Double patterning Outlook Lowest risk route to 32nm half pitch in time But worst in terms of CoO Requires 2 critical masks per critical layer Reduces throughput (~ factor 2) Adds cost of second etch step Impacts total cycle time (additional photo, etch, ) Some integration approaches very critical for alignment Any development improving CoO issues is a plus for double patterning imec 2006 45
Outline Introduction 193 nm immersion lithography EUV Lithography Double patterning Conclusions imec 2006 46
Summary and conclusions Still 3 lithography options for 32nm half pitch critical levels Immersion lithography beyond water urgently needs a 3 rd generation fluid (n>1.8) to be identified EUV lithography makes steady progress First ASML EUV alpha demo tools about ready to ship to the field EUV resist has become issue number one and requires a lot of focus EUVL is the solution for small contact holes! Double patterning is the lowest-risk route towards 32nm but CoO needs to be controlled Towards 22nm volume production, EUVL is the only option imec 2006 47
Double patterning Outlook k 1 as function of NA and half pitch (λ=193nm) Half Pitch (nm) 65 60 55 50 45 40 35 30 25 20 15 193 nm 0.75 0.85 0.95 1.05 1.15 1.25 1.35 1.45 1.55 1.65 NA k 1 = 0.4 k 1 = 0.27 k 1 = 0.20 45nm 32nm 22nm EUVL 0.2 20 0.25 0.30 0.35 imec 2006 48
Aknowledgements STMicroelectronics Lam RESEARCH imec 2006 49 Material Suppliers Software Suppliers Mask shops Equipment Suppliers IC companies The world s largest 193nm immersion lithography effort
Thank you! imec 2006 50