Optical Lithography. Keeho Kim Nano Team / R&D DongbuAnam Semi

Transcription

1 Optical Lithography Keeho Kim Nano Team / R&D DongbuAnam Semi

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4 Lithography = Photolithography = Optical Lithography CD : Critical Dimension Resist Pattern after Development Exposure

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6 Optical Imaging System Light Aperture Illumination Lens Mask Aperture Projection Lens Wafer Source α β

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10 Resolution Limit Result on Silicon Wafer Final Pattern after Lithography Target Layout Mask

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13 Light Intensity Light Source Lens Mask Int. Intensity without Mask Photo Resist

14 Light Intensity Light Source Lens Mask Int. Intensity without Mask Under Process Just Process Over Process

15 Focus & DOF Light Source Lens Mask +Defocus Best Focus DOF -Defocus

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17 Wavelength of Lithography System Ultraviolet F2 ArF KrF i-line h-line g-line nm : 10-9 m

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19 Optical Lithography Resolution = k 1 λ DOF = k 2 NA 2 λ NA Maximized Lithography Margin - OPC - Resolution Enhancement Technique NTI

20 Optical Lithography

21 Optical Lithography Wavelength g-line : 436nm, Hg-Xe Lamp + Optical Filter i-line : 365nm, Hg-Xe Lamp + Optical Filter DUV : 248nm, KrF Excimer Laser 193nm, ArF Excimer Laser F 2 : 157nm, F 2 Laser EUV : 13.4nm, Soft X-ray Exposure Type (Nikon, Cannon, ASML) Step and Repeat : Stepper Step and Scan : Scanner Reduction Ratio 1X(UT), 4X(Scanner), 5X(Stepper), 10X

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23 Stepper (Step and Repeat) Light Mask Optical Lens 1/5 Light Beam Wafer Chip One Shot X Y

24 Exposure System

25 Optic System of Stepper (Canon)

26 Nikon Stepper Structure Reticle Light Source Wafer Projection Lens 22x22mm 2 Field

27 Nikon Scanner Slit : 8x26mm 2 Illumination System Slit 25x33mm 2 Reticle Scanning Stage Projection Lens (Slit) Wafer Scanning Stage

28 Scanner and Stepper

29 Photo Resist Resist Tone Positive : Exposed Resist (Decomposition) => Removed after Development Mask Tone == Resist Pattern Tone Negative : Exposed Resist (Cross Link) => Remains after Development Mask Tone <=> Resist Pattern Tone Mask Positive Negative

30 Photo Resist Resist Component (Sumitomo, TOK, JSR, Shin-Etsu) Sensitizer : Reaction to Light Resin : Masking to Etching Solvent : Viscosity Adjustment for Coating Thickness = Thickness(Spin Speed, Viscosity, Others) i-line Resist PAC(Photo Acid Compound) + Novolac + Solvent Exposed PAC => Decomposition => Higher Dissolution Rate DUV (KrF) Resist (Chemically Amplified Resist) PAG(Photo Acid Generator : Proton-Catalyst) + PHS + Solvent Proton Catalyze Decomposition or Cross-linking PHS => Acetal(Low Temp) / t-boc / Acrylate(High Temp)

31 In-line Process AD HP HP HP HP HP WDS WEE HP COL COL COL COL COL C/S M/A I/F COAT DEV DEV Track System Exposure System

32 Nikon Stepper & Scanner NSR-2205i14E NSR-S203B NSR-S204B

33 ASML Scanner Click Here

34 TEL Track System Mark-8 ACT-8

35 CD-SEM System PCD001 : S-9220 (Hitachi) PCD003 : S-9260 (Hitachi)

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38 Off-axis Illumination -1st Order +1st Order -1st Order +1st Order 0th Order 0th Order Conventional Off-Axis

39 Coherence Factor (σ) Effect 1 σ = 0 σ = 0~2 σ = 0 Cut Off (λ) 1/Pattern Size -1st Order 0th Order +1st Order Projection Lens (Diameter ~ NA)

40 Apertures for Off-axis Illumination σ Conventional Modified Illum. / OAI? Annular SHRINC Quadruple

41 Dipole

42 Phase Shift Mask Making Formula Shifter d OPD = = d ( n n 1 λ 2 shifter air )

43 Phase Shift Mask Mask Conventional Half Tone (4~15%) Strong PSM E-field at Mask E-field at Wafer Intensity at Wafer

44 Strong PSM Conventional Alternating (Old) Qz Cr Shifter 180 o 0 o Cr-less (Qz Etch) Alternating 0 o 180 o Shifter 180 o 0 o

45 Actual PSM Application Double Exposure Process

46 Sub Resolution Assist Features SRAF (OPC) => Process Margin Improvement

47 Pattern Type Line and Space Pattern (Pitch, Duty Ratio=Line:Space CD) Pitch CD 1:1 L/S 1:2 L/S Iso Line Iso Space

48 Pattern Type Contact Hole (Island) Pattern (Pitch, Duty Ratio=Contact CD : Spacing) Pitch CD 1:1 C/H Iso C/H Island Pattern

49 CD Linearity & Focus Margin Shin-Etsu Data

50 Actual Device Pattern Moat Design Mask Pattern (Cr / Quartz) Resist Pattern on Wafer =>

51 Actual Device Pattern Gate Design Mask Pattern (Cr / Quartz) CD Target Pattern =>

52 Mask Design / Simulation Data CD CD SEM Measurement after Development CD

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57 Simulation Sequence Aerial Image Mask Latent Image Development Contours 3-D Resist Structure

58 Image Intensity => Resist Pattern Diffusion

59 Lithography Sim. Example 2-D Resist Profile 3-D Resist Profile

60 Resist Profile Cross Section

61 What s OPC? Optical Proximity Effect Correction Mask Pattern Original Pattern OPC Tool Corrected Pattern Resist Pattern

62 OPC Type Serif Jog Hammer Head Extension Scattering Bar

63 OPC at IBM

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66 EUV Lithography Intel

67 SCALPEL 0.1mm Si Strut 1.1mm Membrane : SiN X ~100nm Low atomic number Scatterer : Cr/W 10nm/30nm High atomic number

68 Electron Projection Lithography