Scope and Limit of Lithography to the End of Moores Law Burn J. Lin - PowerPoint PPT Presentation

Scope and Limit of Lithography to the End of Moore’s Law Burn J. Lin tsmc, Inc. 1 Tsmc property March. 2012

What dictate the end of Moore’s Law Economy Device limits Lithography limits 2 Tsmc property March. 2012

Litho Requirement of Critical Layers Logic Node (nm) 32 22 16 11 8 Poly Half Pitch (nm) 45 32 22 16 11 CD Uniformity (nm) 3.2 2.2 1.6 1.1 0.8 Overlay Accuracy (nm) 9.6 6.6 4.8 3.3 2.4 These are generic technology nodes that have no correlation to TSMC nodes 3 Tsmc property March. 2012

Pushing the Limits of Lithography Pitch splitting with ArF water immersion Further wavelength reduction to EUV Multiple E-Beam Maskless lithography 4 Tsmc property March. 2012

Resolution of Tools from ArF to MEB   MFS k 1 NA  n  DOF k 3 2 NHA 5 Tsmc property March. 2012

Multiple Patterning Double patterning => L + E + L + E = 2L2E Triple patterning => 3L3E Multiple patterning can be used for Pitch splitting Pattern trimming Spacers 6 Tsmc property March. 2012

Pitch Splitting Combining two patterns and shrink 7 Tsmc property March. 2012

Combined Intensity in Resist 8 Tsmc property March. 2012

Better End Caps With Double Exposures Double Double Single exposures in exposures exposure resist through etch. 2 coatings 2 exposures 2 developments ADI 2 etches AEI 9 Tsmc property March. 2012

Triple Patterning Using Split Pitch and End Cutting Resist 1 Resist-1 and etchd hardmask images Wafer Resist 2 Hardmask Final-pattern material Strip resist 1, coat and image resist 2 Wafer Resist 3 Etch final-pattern layer. Coat and image resist 3 to cut line end. Wafer Final pattern Final pattern from the end-cutting Wafer resist mask. 10 Tsmc property March. 2012

Split Pitch with Line-End Cutting Mask B Mask A Mask C Cut Active 11 Tsmc property March. 2012

Realistic Considerations on DPT Resist 1 BARC 1 BARC 1 Hardmask Resist 2 BARC 2 BARC 2 Etched device pattern Some CD and Device with line edges are CD not overlay error changed affected 12 Tsmc property March. 2012

Contact Pitch Splitting C A B Watch out for G-rule violation Mask 1 Mask 2 13 Tsmc property March. 2012

More G-Rule Violations P 4 P 5 P 4 P 5 P 1 P 1 P 2 P 2 P 6 P 6 P 3 P 3 P 7 P 7 Conflicting space P 4 P 4 P 5 P 5 P 1 P 1 P 2 P 2 P 6 P 6 P 3 P 3 P 7 P 7 14 Tsmc property March. 2012

Split Masks with Hollow SB and OPC Mask A Mask B 15 Tsmc property March. 2012

Triple Patterning Using Spacers Spacer Resist-1 image (not shown) is used to delineate the spacer host pattern. Wafer Conformable coating & anisotropic etching produce sidewall spacers. Spacer host Resist 2 Resist-2 image protects selected spacers. Wafer Hardmask Final-pattern material Resist 3 Resist-3 image is the etch mask for features larger than the spacer width. Wafer Final pattern Final pattern from hardmask that was delineated with the composite spacer Wafer and resist-3 images. 16 Tsmc property March. 2012

Multiple Patterning in ArF Immersion Logic Node 32nm 22nm 16nm 11nm 8nm Poly Half Pitch (nm) 45 32 22 16 11 Contact Half Pitch (nm) 50 35 25 17 12 Metal Half Pitch (nm) 45 32 22 16 11 Immersion k 1 for Poly 0.31 0.22 0.15 0.11 0.08 Immersion k 1 for Contact 0.35 0.24 0.17 0.12 0.08 Immersion k 1 for Metal 0.31 0.22 0.15 0.11 0.08 2 2 3 4 Multiple Patterning 1 Immersion k 1 for Poly 0.31 0.45 0.31 0.34 0.31 Immersion k 1 for Contact 0.35 0.49 0.35 0.36 0.34 Immersion k 1 for Metal 0.31 0.45 0.31 0.34 0.31 17 Tsmc property March. 2012

EUV Lithography 18 Tsmc property March. 2012

EUV Illuminator and Imaging Lens In-band On collector EUV light 9.36P Watt 26.8P W 2nd normal On 1st NI incidence mirror 6.37P mirror Watt On mask 550P mW On wafer Grazing 1P mJ/cm 2 , incidence M6 30P mW for mirrors M1 100 wph 370P mW M2 M3 M5 M4 19 Tsmc property March. 2012

EUVL Results CD = 5 2 nm Focus = 0 nm CD = 5 4 nm CD = 5 3 nm N32 SRAM contact holes Focus = - 4 0 nm Focus = + 4 0 nm 20 Tsmc property March. 2012

k 1 of EUVL Node 22nm 16nm 11nm 8nm NA 0.25 0.32 0.32 0.45 EUV k 1 for Poly 0.59 0.52 0.38 0.37 EUV k 1 for Contact 0.65 0.59 0.40 0.40 EUV k 1 for Metal 0.59 0.52 0.38 0.37 21 Tsmc property March. 2012

One Implication of k 1 Contrast at Line End 0.1 -0.2 0.1 0.1 -0.5 -0.2 -0.2 -0.8 -0.5 -0.5 -1.1 -0.8 -0.8 -1.4 -1.1 -1.1 -1.7 -1.4 -1.4 -2.0 -1.7 -1.7 -2.3 -2.0 -2.6 -2.9 180nm node, 130nm node, 250nm node, k 1 =0.47  =248nm k 1 =0.42  =248nm k 1 =0.63  =248nm NA=0.54 NA=0.67 NA=0.5 Disk Illumination  = 0.8 22 Tsmc property March. 2012

Positioning Errors due to Mask Rotation and Translation From M1 To M6 Mask  =6 0 a Wafer a'    m   x' a'  Z tran  m  X 2  Z tran tan   z' X  Off-center tilt Mask surface misposition 23 Tsmc property March. 2012

EUV Mask Flatness Requirement Node 22nm 16nm 11nm 8nm  (deg) 6.0 6.0 6.0 8.0 tan(  ) 0.105 0.105 0.105 0.141 Mask flatness 46.5 33.8 23.3 12.6 required (nm) Flatness of best immersion mask: 500 nm 24 Tsmc property March. 2012

Shadowing from Oblique Illumination CD needs to be compensated according to feature location and orientation (Courtesy Lorusso, IMEC) 25 Tsmc property March. 2012

Stray Light from Lens Surfaces Scattering by Scattering by surface roughness a dust particle Specular reflection for imaging EUV flare ~10% vs. < 0.1% UV flare 26 Tsmc property March. 2012

OPC Considerations Uneven flare and shadowing effect require field- dependent OPC . Inter-field flare necessitates dummy exposures at wafer edge. Flare signature if inconsistent between scanners, requires dedicated mask . Flare stability still unknown. 27 Tsmc property March. 2012

On Lack of Pellicle Developed reticle box for freedom from contamination during storage, transportation, loading/unloading. Attraction of particulates by the electrostatic mask chucking has to be minimized. Need to block line-of-sight exposure to Sn debris source. Maintain high vacuum. Minimize presence of trace Carbon-containing vapor and H 2 O vapor . 28 Tsmc property March. 2012

Mask and Pellicle 6 mm 3  m 300 nm 85 mm 29 Tsmc property March. 2012

Summary of EUVL Concerns Need 250 W at IF. Currently < 10 watt. Mask defect and flatness. Field-dependent OPC. Time-dependence of OPC can be detrimental. 30 Tsmc property March. 2012

EUV Extendibility 31 Tsmc property March. 2012

High-NA EUV Design Solutions NA 0.25 0.32 0.4x 0.7 central 6 mirrors obscured central unobscured 8 mirrors obscured 27 nm 16 nm 11 nm 8 nm NXE:3100 NXE:3300 W. Kaiser et al., SPIE 2008 schematic designs – for illustration only. 32 Tsmc property March. 2012

NA and k 1 of Photon Tools Node 22nm 16nm 11nm 8nm Half pitch (nm) 32 22 16 11  (nm) ArF 193 193 193 193 water NA 1.35 1.35 1.35 1.35 k 1 immersion 0.22 0.15 0.11 0.08  (nm) EUV at 13.5 13.5 13.5 13.5 constant NA 0.25 0.36 0.50 0.73 k 1 k 1 0.59 0.59 0.59 0.59  (nm) EUV at 13.5 13.5 13.5 13.5 diminishing NA 0.25 0.32 0.32 0.45 k 1 k 1 0.59 0.52 0.38 0.37 Cannot maintain constant k 1 because of • Diminishing DOF • Expensive NA 33 Tsmc property March. 2012

One Implication of k 1 Contrast at Line End 0.1 -0.2 0.1 0.1 -0.5 -0.2 -0.2 -0.8 -0.5 -0.5 -1.1 -0.8 -0.8 -1.4 -1.1 -1.1 -1.7 -1.4 -1.4 -2.0 -1.7 -1.7 -2.3 -2.0 -2.6 -2.9 180nm node, 130nm node, 250nm node, k 1 =0.47  =248nm k 1 =0.42  =248nm k 1 =0.63  =248nm NA=0.54 NA=0.67 NA=0.5 Disk Illumination  = 0.8 34 Tsmc property March. 2012

DOF of EUV Node 22nm 16nm 11nm 8nm  (nm) EUV at 13.5 13.5 13.5 13.5 diminishing NA 0.25 0.32 0.32 0.45 k 1 k 1 0.593 0.521 0.379 0.367 DOF (k 3 ) 0.612 0.557 0.242 0.235 Theoretical (nm) 520 286 124 59 Experimental (nm) 300 DOF determined with common E-D window • 0.4:0.6 Resist line : space • Allowance for mixed pitches 35 Tsmc property March. 2012

13.5nm light may be reaching physical resolution & DOF limits at 11nm Half Pitch or earlier. 36 Tsmc property March. 2012

It may reach the economic limit much earlier. 37 Tsmc property March. 2012

Multiple E-Beam Maskless Lithography 38 Tsmc property March. 2012

REBL System Digital Pattern Generator  Reflective Electron Optics Illumination Optics  Digital Pattern Generator (DPG) EXB Filter Projection Optics Electron Gun  TDI (Temporal Dose Integration) WMS  Optical Wafer Registration Demag Optics  Maglev Stage Technology Multiple Wafer Linear Stage 39 Tsmc property March. 2012

Rotary & New Linear Stages for REBL HVM  E-beam column has to have 10-cm diameter or smaller.  HVM throughput goals are similar in both stages.  Stage design, data path, and rendering algorithms are simpler for linear stage. HVM Rotary Design, 36 Columns HVM Linear Design, 36 Columns 40 Tsmc property March. 2012