Key Technologies for Next Generation EUV Lithography September 15, 2017 Toshi Nishigaki Vice President and General Manager Advanced Semiconductor Technology Division / Tokyo Electron Limited Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 1
Contents Process requirements for EUV lithography EUV pattern roughness and shape control EUV resist sensitivity and contrast enhancement EUV resist defect reduction Summary Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 2
Process requirements for EUV lithography Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 3
EUV lithography patterning requirements TEL CLEAN TRACK LITHIUS Pro Z Coater/Developer ASML NXE EUV exposure tool Smoothing by etching LER(roughness) /Local pattern fidelity Resolution Pattern defects Higher resist contrast Defect reduction by CLEAN TRACK Resist sensitization EUV Sensitivity Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 4
EUV patterning performance improvement using equipment set Coater/Developer Coat EUV Exposure Develop Plasma etch system Single wafer deposition system Thermal processing system Deposition Dry Etch Cleaning system Anneal Wet Clean Surface Planarization Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 5
SPIE 2017 joint paper EUV pattern roughness and shape control From SPIE Vol. 10143, 1014315 (2017) TEL, ASML, imec and SPIE Vol. 10149, 101490N (2017) TEL, ASML, imec Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 6
EUV lithography overall patterning optimization TEL CLEAN TRACK LITHIUS Pro Z Coater/Developer ASML NXE EUV exposure tool EUV Source Mask Optimization (SMO) with ASML EUV source shape Co-optimization of lithographic and patterning processes is the key for improved EPE performance by EUV lithography Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 7
EUV stochastic events enhances pattern roughness Optical Photons/nm 2 for 15 mj/cm 2 193-i EUV Chemical Resist film :Polymer :Protection group :Un-protected (hydrophilic) group :PAG De-protection photon 145 10 H + H + e - H + H + Exposed region Un-exposed region Exposed region Un-exposed region Dissolution H + H + H + Polymer-aggregation M. Krysak et al., SPIE Proc. 7639, 76392C (2010) M. Krysak et al., SPIE Proc. 72732, 72732N (2009) Stochastic events induced by limited numbers of photons, secondary electrons and chemical spices in a small pattern causes pattern roughness Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 8
CD variation on EUV via pattern 16.5 17 17.5 18 18.5 19 19.5 20 20.5 21 21.5 22 22.5 23 23.5 24 24.5 25 25.5 26 26.5 27 CD (nm) CD variation in EUV lithography by shot noise effect is a big challenge Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 9
Micro-loading effects during plasma treatment Etching rate Deposition rate Small open area Etch rate : Slow Depo rate : Slow Large open area Etch rate : Fast Depo rate : Fast Narrow space Wide space Solid angle Micro-loading effect for etching and deposition can be used for CD healing and control Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 10
CD-healing effect on EUV pattern by plasma treatment ADI 2 1.5 Contact Edge Roughness: CER (nm) vs CD Ave.CER = 0.8 nm ADI AHI AHI CER (nm) 1 Ave.CER = 0.5 nm 0.5 3σ = 2.9 nm 0 16 18 20 22 24 26 28 AHI : after healing inspection CD (nm) 3σ = 3.4 nm CDU and CER can be greatly improved by plasma treatment in a etcher Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 11
Global CDU improvement for EUV lithography by CD healing ADI (Lithography) AEI (Etching only) AHI (CD healing) AHI + DOMA (CD healing with litho CD control) CDU: 1.95 nm CDU: 2.13 nm CDU: 1.77 nm CDU: 1.07 nm DOMA: Dose mapper by ASML Global CD uniformity can be improved with DOMA and CD healing (AHI) Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 12
EUV CDU improvement on short trench by plasma treatment ADI Post shrink CDU on CDx CDU on CDy 12 12 : ADI B-2 B-3 10 CDx 10 CDy : post shrink B-1 27.3nm 11.0nm Local CDU(nm) 8 6 4 8 6 4 2 2 0 B-1 B-2 B-3 0 B-1 B-2 B-3 Stochastics pattern fidelity errors can be mitigated by plasma treatment in a etcher Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 13
CD control on short trench for line-cutting by plasma treatment 21 nm ADI (EUV) 27.3 nm Hole shrink process scheme by etching tool Cut pattern shape control is important for wider process margin Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 14
Hole / trench shape control realized by plasma treatment in etcher Circularized Shortened Oval pattern Short trench pattern Keeping original shape Keeping original shape Cut pattern shape control is possible by tuning x/y etching/depo ratio Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 15
SPIE 2017 joint paper EUV resist sensitivity and contrast enhancement From SPIE Vol.10146,101460G (2017): TEL, JSR, imec, Osaka University, Synopsys, PSI Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 16
EUV lithography faces sensitivity and stochastic effect tradeoff Photon distribution Resist patterns z x y Pitch = 32 nm PSCAR can be one of the solutions of sensitivity enhancement and shot noise mitigation Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 17
2.0 components Protected polymer Photosensitizer precursor (PP) PS-PAG PS-PDB (quencher) New for 2.0 2.0 *PS-PAG: Photo-acid generator which can be photosensitized *PS-PDB: Photo-decomposable base type quencher which can be photosensitized Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 18
EUV dose reduction by sensitization using 2.0 2.0 PSCAR 2.0 with PS-PDB shows good sensitization Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 19
Simulation of higher chemical contrast by 2.0 16nm HP L/S After EUV exposure (20 mj/cm 2 ) Acid neutralization Flood exposure (No flood) After PEB (Quencher) PDB CAR Quencher loading: 0.0793 Protected polymer (m) dm/dx = 0.058 After EUV exposure (20 mj/cm 2 ) Acid neutralization & PS generation Flood exposure (1510 mj/cm 2 ) After PEB x2.15 PS-PDB PSCAR 2.0 Quencher loading: 0.60 (Quencher) Protected polymer (m) dm/dx = 0.125 BETTER Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 20
Line width roughness (LER) reduction by 2.0 16 nm L/S EUV exposure dose: Fixed at 20 mj/cm 2. Flood exposure dose: 0 J/cm 2 for CAR; 5 J/cm 2 for PSCAR. Quencher amounts are optimized to get 16 nm HP. With PDB (Photo Decomposable Base) quencher LER (nm) Stochastic Simulation by S-Litho prototype CAR 2.0 PSCAR 2.0 with PS-PDB has a potential to reduce LWR Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 21
SPIE 2017 joint paper SPIE 2017 joint paper EUV resist defect reduction From SPIE Vol.10143, 1014326 (2017) TEL, imec SPIE Vol.10143, 101430 (2017) IBM Research, TEL Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 22
Major types of pattern defects in EUV lithography: 24 nm HP CH Residue defect In-film particle Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 23
EUV defect budget analysis: 24 nm HP CH After development inspection(adi) ADI Defect Budget Others 1% After etch inspection (AEI) AEI Defect Budget Others 2% CLEAN TRACK LITHIUS Pro Z-EUV and NXE:3300B In-film particle 44% Residue defect 55% In-film particle 52% Residue defect 46% Tactras for etching Residue defect and in-film particle are the dominant before and after etching Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 24
EUV resist defect transfer after etching ADI stack Resist SOG (10 nm) SOC (75 nm) Si-Ox (20 nm) TiN (15 nm) Si-Ox (20 nm) Si Normalized defectivity 1.4 1.2 1 0.8 0.6 0.4 0.2 0 ADI Other In-film particle Residue AEI Increase of in-film particle 100% transfer of residue AEI stack Si-Ox TiN Si-Ox Si 100% of residue defect was transferred to AEI Increased in-film particles was transferred to AEI Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 25
Approach for residue defect reduction Rinse process EUV resist: Higher contact angle than immersion resist after development Dry Residue Dry Non-optimal Optimal Remaining water causes residue defects Rinse process after development was optimized for residue defect reduction Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 26
Approach for in-film particle reduction Resist SOG SOC Underlayer In-film particle Defect Resist SOG SOC Underlayer SOG SOC Underlayer Defect count increases from ADI to AEI Defect Resist dispense SOC Underlayer Defect Defect Conventional NDS New Dispense System(NDS) reduces coating process defects Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 27
Residue defect and in-film particle reduction result after applying optimized rinse and NDS 1.4 Others In-film particle Residue Normalized defectivity 1.2 1.0 0.8 0.6 0.4 73% reduction 72% reduction 79% 79% 69% 69% In-film particle 42% Others 10% Residue defect 48% 0.2 0.0 Conv. Dispense Rinse & Opt. Rinse NDS& NDS Conv. + Flow + C Conv. Flow rinse A Optimized rinse ADI Conv. Dispense Rinse & Opt. Rinse NDS& NDS Conv. + Flow + C Conv. Flow rinse A Optimized rinse AEI Two dominant defects were reduced over 70% by combining optimized rinse and NDS Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 28
Conditions o EUV Scanner : NXE3300B o Resist: EUV Resist A o Pattern: 18 nm L/S EUV pattern collapse mitigation by rinse process optimization Enabling EUV resist features with aspect ratio >1 through development of rinse materials This work was performed by the Research Alliance Teams at various IBM Research Facilities Pattern collapse comparison: SEM images P Target CD -1nm -2nm -3nm -4nm -5nm -6nm DIW DIW Rinse A Material Material A (Conventional) (Conventional) Pattern collapse margin Rinse New Rinse MMaterial aterialc DIW Rinse material A CD uniformity with rinse material C Rinse material C Rinse Material A Rinse Material C CD delta map Pattern collapse margin can be improved without impact in CDU Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 29
Summary Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 30
Summary EUV patterning challenges and TEL s solutions were reviewed. TEL s plasma treatment technology in a etcher provides pattern CD(CDU/CER) healing capability and shape control capability. EUV resist sensitization and resist contrast enhancement activity is ongoing. CLEAN TRACK LITHIUS Pro Z reduces pattern defects and pattern collapse issues with newly introduced technologies. TEL will continue to provide new technologies to support EUV HVM including EUV specific stochastic events. Toshi Nishigaki / Tokyo Electron Limited / September 15, 2017 / IC Forum, SEMICON TAIWAN 2017 31